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Problem

Systemized or thodont ic

t reatment mechanics

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Systemized or thodont ic

t reatment mechanics

Richard P McLaugh l in

S a n D i e g o , C a l i f o rn i a , U S A

John C Benne t t

L o n d o n ,  UK

Hugo J Trevis i

Pres iden te Pruden te , B raz i l

- . ■

M  Mosby

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MOSBY

An imprint of Harcourt Publishers Limited

© Mosby In terna tional I-(d 2001

M is a registered tradem ark of I  larcourt Pu blishers Limited

The right of L)r Richard P McLaughlin, Dr John C Bennett and Dr

 1

 lugo

  I

  Trevisi to be identified as

authors of this work has been asserted by them in accordance with the Copyright , Designs and Patents

Act 1988

All rights reserved. No pail of this publication may be reproduced, stored in a retrieval system, or

transmitted in any form or by any means, electronic, mechanical , photocopying, recording or

Otherwise, without ei ther the prior permission of the publishers (Permissions Manager, Harcourt

Health Sciences, Robert Stevenson House, 1-3 Baxter's Place, Leith Walk, Edinburgh EH1 3AF), or a

licence permitting restricted copying in the Llniled Kingdom issued by the Copyright Licensing Agency,

90 Tottenha m Court Road, London W l I' OI.P.

f irs t published 2001

1SBN072343171X

Brit ish Library Cataloguing in Publicat ion Data

A catalog ue record for this boo k is available from the British Library

Library of Congress Cataloging in Publicat ion Data

A catalog record for this book is available from the Library of Congre ss

The

publisher's

policy is lo use

paper manufactured

from sustainable forests

Typeset by IMH(Cartrif), Loanhead, Scotland

Printed in Spain

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PREFACE AND ACKNOWLEDGEMENTS

- .aai i'n 1  ̂ii n Hiii ii  ttmBamargemKsmamBBmuBammmmmBimmmmmmammmmmmmmmmmmmmmm

Goal -d i rec ted o r t hd don t ic t rea tm en t is ex t remely imp or ta n t .

If the goals of t rea tm ent goa ls are no t kept in min d from the

d iagnos i s and t rea tmen t -p lann ing phase th rough lo the phase

of re ten t ion , co n t in uou s e r ro rs can be ma de . T rea tmen t then

becomes inefficient and resul ts are dis ap po int ing . How ever,

if t reatmen t goals are kept constan t ly in min d, resul ts b ec om e

m u c h m o re c o n s i s te n t , a n d wh e n m i n o r c o m p ro m i s e s m u s t

occur , the reasons fo r these can be unders tood , and many o f

them can be avoid ed in the future. The goals of t rea tm ent for

the autho rs are l is ted belo w. They ho pe the read er wil l keep

these in mind when reading the text , to provide greater

insight into thei r inte nt. It is ho pe d tha t in th at way it will

have more mean ing . The t rea tmen t goa l s a re :

• Cond yles in a seated posi t io n - in centric re lat ion

• Relaxed heal th y mu scu latu re

• A 'six keys' (Mass I occ lus ion

• Ideal func t iona l mo vem ent s - a mu tua l ly p ro tec ted

occlusion

• Periodontal hea l th

• Best possible aesthet ics .

Th is book was o r ig ina l ly p lanned as a second ed i t ion o f

the fi rs t Bennett and McLaughlin text , ent i t led

  Orthodontic

Treatment Mechanics and the Preadjusted Appliance,

  p u b l i s h e d

in 1993 . However , there have been so many techno log ica l

changes and improvements over the pas t 8 years tha t an

en t i re ly nex t t ex t became necessary , supp lemen t ing the

general message of the first.

A second Bennet t and M cla ugh l in t ext , en t i t l ed

  Orthodontic

K4anagemenl  of the Dentition with the P readjusted Appliance,  wa s

published in 1997. T his dev oted a cha pter to each too th in

the den t i t ion , emphas iz ing c l in ica l s i tua t ions re la t ing to each

tooth. I t evolved into a far m or e extensive project tha n

ini ti al ly in tended , and requ i red a subs tan t ia l ma nusc r ip t to

cover the wide range of material .

With this th ird textb ook, t he in te nt io n is to retur n to a

concise format somewhat s imilar in scope to the fi rs t . I ts

p r imary focus is on o r tho don t ic t rea tmen t m echan ics , in

par t i cu lar in t ra -arch cons idera t ions , o r the maneuvers

invo lved in a l ignment and main tenance o f the den t i t ion in

each individual arch. These factors are deal t with in Chapter

5 Anchorage con t ro l du r ing too th l eve l ing and a l ign ing ' ,

Chapter 6 'Arch level ing and overbi te control ' , Chapter 9

'Space c losu re and s l id ing m echan ics ' , and Ch ap te r 10

'Finishing the case ' . In ter-arc h consid era t ion s, or the

coord ina t ion o f the upper and lower a rches in th ree p lanes o f

space within the facial complex, are also given a s l ight ly

g rea te r emphas i s than p rev ious ly ; in par t i cu lar , Chap ter 7 and

8 deal with Class II t reatment and Class III t reatment ,

respec t ive ly . These a re ex tens ive sub jec t s , bu t an a t t empt has

been made to p resen t a concise and up- to -da te perspec t ive on

the genera l management o f these two ca tegor ies o f case .

Th e tex t d i scusses bo t h ex t rac t ion and non-e x t rac t ion

t rea tm en ts . Grea ter em pha s i s is p laced on ex t rac t ion

t rea tmen t , because the mechan ics o f these cases a re more

com plex . This is no t to infer tha t the au tho rs t reat mor e cases

on an extract ion basis ; in general , every effort is made to t reat

on a non-ex t rac t ion bas i s wherever poss ib le , and the au thors

t rea t a much h igher percen tage o f cases in th i s manner .

Af te r us ing the o r ig ina l 'S t ra igh t -Wire* App l iance ' (SWA)

for near ly 20 years , i t became impor tan t to p rov ide

m o d i f i c a t i o n s t o t h e a p p l i a n c e t o m o re c l o s e l y c o m p l e m e n t

m o d e rn t r e a t m e n t m e c h a n i c s . C h a p t e r 2 o n a p p l i a n c e

spec i f ica t ion dea l s wi th the ra t iona le beh ind the changes

ma de in the app l ian ce sys tem. Em phas i s i s p laced on th e new

variat ions, as well as on the versat i l i ty of the appliance

(compar i sons a re res t r i c ted to the o r ig ina l SWA and do no t

re fer to o ther o r thodon t ic app l iances ) .

A b racke t p lace me n t char t , deve loped in 1995 , has been

mos t va luab le in the im por tan t a rea o f b racke t p lace men t .

The tex t d i scusses recen t deve lopments in b racke t -p lacemen t

techn iques - renewed in te res t in ind i rec t bond ing , fo r

ins tance , has occurred because o f improved mater ia l s , such as

adhes ive sys tems and t ray mater ia l s . An overv iew o f th i s

subject is provided.

Archwire t echno logy has improved d ramat ica l ly over the

pas t 8 years . Th e use o f hea t -ac t iva ted n icke l - t i t an ium wires

( I IANT) has beco me a vi ta l part o f the t rea tme n t sys tem, and ,

c o n s e q u e n t l y , m o d i f i c a t i o n s t o t h e t r e a t m e n t m e c h a n i c s h a v e

occurre d . In fo rm at ion o n HANT wires , a lon g wi th a

d i scuss ion o f a rchwire sequencing , i s p resen ted in Chap ter 5

'Anchorage con t ro l du r ing too th l eve l ing and a l ign ing ' .

S ince i t s in t roduct ion in the 1970s , a t t empts have been

made wi th the p read jus ted app l iance to se lec t and use a s ing le

arch fo rm on m os t pa t ien t s . Even us ing the mos t f requen t ly

observed arch fo rm in the o r tho do n t i c pop u la t ion , the

au thors observed numerous cases tha t were e i ther too narrow

or over-e xpand ed . Therefo re , Cha p ter 4 is ded ica te d to the

subject of arch form, and presents efficient techniques for

manag ing arch fo rm se lec t ion and archwire coord ina t ion .

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Chap ler 11 is ded ica te d to re te n t ion p ro toc o l , wh ic h i s a

new subject for th is text . I t g ives an overv iew of the pro toc ol ,

as well as desc ribing the me th od s mo st frequently used by th e

authors .

Drs Bennett and McLaughlin have spent a great deal of

t ime wi th Dr Hugo Trev is i o f Pres iden te Prud en te , Brazi l, w ho

has used this system of t re atm en t for over 20 years . Dr Tre vis i

has p rov ided a num be r o f im por tan t in s igh ts in to the

techn ique , and therefo re a dec i s ion w as mad e to in t rodu ce

him as a th ird author of the text , thus reinforcing i ts

in te rna t iona l perspec t ive , and b r ing ing toge ther the bes t ideas

from three continents .

The success of a project of th is scope and complexity

d e p e n d s o n t h e c o m m i t m e n t o f m a n y i n d i v i d u a l s . T he

a u t h or s a c k n o wle d g e a n d a p p re c i a t e t h e d o c u m e n t a t i o n s k il ls

and extra photography carried out by the assis tants in each of

the autho rs ' pract ices . The w ork of Pat ty Knecht an d Laura

I ' lanie in San Diego, and Cath West in London, was

invaluable, as were the in terpret ing ski l ls of Michelle Trevis i

Araujo in Brazil.

Text and i l lu s tra t ions were assemble d in Londo n , and

product ion and pub l ica t ion were hand led by the Mosby team

in Ed inburgh . On behal f o f the pub l i shers , Barbara S immons ,

p ro jec t deve lopment manager , and her co l leagues con t r ibu ted

unfai l ing energy' and ent hus ias m to th is project . The ir

p ro fess iona l ism a nd respec t o f the au th ors ' so me t im es

unconven t iona l work pa t te rns he lped make the pub l i sh ing

process both efficient and enjoy able . Th e au th or s freely

acknowledge the valuable help and advice given by Michael

Park inson , com miss io n ing ed i to r . They a l so wish to m ake

p a r t i c u l a r m e n t i o n o f t h e c o n t r i b u l i o n o f Gra h a m B i rn i e , wh o

labor iou s ly checked and ed i ted the o r ig ina l t ex t, and o f lud i th

W r i g h t , w h o wa s r e s p o n s i b l e fo r t h e d e s i g n . L o o k i n g a h e a d ,

there a re p lans fo r a t l eas t 12 fo re ign co -ed i t ions , and the

au t hor s a re g ra te fu l to I lona Turn iak fo r her work on d i i s

i m p o r t a n t a s p e c t o f p u b l i c a t i o n .

C h a p t e r s 7 a n d 8 i n c l u d e i n fo rm a t i o n o n t h e d i a g n o s t i c

methods o f Dr Bi l l Arne t t , who gave cons iderab le t ime and

a s s i s ta n c e , a n d m a d e i m p o r t a n t m a t e r i a l a v a i l a b l e for C h a p t e r

8 . Th e au tho rs a re a l so g ra te fu l for Dr Fredr ik Bergs t ra nd ' s

a d v i c e o n b o n d i n g , a n d for t h e p h o t o g ra p h . T h e a u t h o r s '

work has benef i t ed over the course o f many years f rom the

i n p u t o f i n t e rn a t i o n a l c o l l e a g u e s - a l t h o u g h s p a c e c o n s t r a i n t s

make i t imposs ib le to acknowledge each ind iv idua l ly , the i r

f r i e n d s h i p , e n t h u s i a s m a n d s u p p o r t d o e s n o t g o

u n re c o g n i z e d .

T h e fo l lo wi n g t e c h n i c a l p ro d u c t i o n i n fo rm a t i o n m a y b e o f

in te res t . Th e o r ig ina l t ex t was gene ra ted in App le Work s 5 .0

on a Ma cin tosh C4 com put er . L ine d raw ings were c rea ted in

Apple Freehand 8 .0 , and tee th a re rep resen ted approx imate ly

to sca le , wi th fo rm based on den ia l ana tomy tex t s . The co lo r

p h o t o g r a p h s we re m a i n l y o r i g i n a l e d in Ko d a c h ro m e 6 4 . No

d ig i ta l en ha nc em en t o f c l in ica l mater ia l too k p lace . Apa r t

from the removal of red-eye on some of the facial

ph o to gra ph s , il has been pu b l i sh ed d i rec t ly f rom the o r ig ina l

Ko d a c h ro m e s l i d e s .

F ina l ly , the au thors wou ld l ike to thank 3M Uni tek fo r i t s

e f fo r t s in des ign ing the new app l iance , as wel l as fo r suppor t

in the o ther a reas o f the t rea tmen t sys tem, such as b racke t -

p l a c e m e n t g a u g e s a n d c h a r t s .

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CONTENTS

1. A br ie f h is tory an d overview of t rea tm en t m ech anic s 1

2.

  Appliance specificat ion s  -  var ia t io ns an d versa t i li ty 25

3.  Bracket pos i t ion ing and case se t -up 55

4.

  Arch  form 71

5.

  Anchorage con t rol du r in g too th leve l ing an d a l ign ing 93

6.  Arch  level ing and overb i te con t rol 129

7.

  An overview of Class  II  t rea tm ent 161

8. An overview of Cla ss

  111

  t r e a t m e n t 2 1 7

9.  Space c losure and s l id in g me cha nics 249

10.

  Finishing th e case 27 9

11.  A ppl iance removal and re ten t ion pro toco ls 30 5

Index  319

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CHAPTER 1

A br ief h is to ry an d o v erv iew o f

t reatment mechanics

Introduction 3

Fundamentals of treatment mechanics  3

Bracket design

Bracket positioning

Archwire selection

Force levels

The  work  of And rews 4

Wide range of brackets

Center of the crown

Various arch forms

Heavy forces

The  work of Roth  6

Roth brackets

Center of the crown

Wide arch form

Articulators

McLaughlin and Bennett 1975 to 1993  7

Mainly standard brackets

Center of the crown

Ovoid arch form

Light forces and sliding mechanics

The work of McLaughlin, Bennett, and Trevisi

between 1993 and 1997  8

Re-designed bracket system - MBT™

Improved bracket posit ioning with gauges

The work of McLaughlin, Bennett, and Trevisi

between 1997 and 2001 12

The decis ion to use three arch forms

Updated l ight forces and s liding mechanics

Overview of the MBT™ treatment ph ilos op hy 13

Bracket selec tion 13

Versatility of th e bracke t system 13

Accuracy of bracket po siti on ing 13

Light co nt in uo us forces 13

The .022 versus the .018 slot 14

Anchorage contro l early in treat m ent 15

Gro up mov ement 16

Th e use of three arch form s 16

O ne s ize of rectangular s teel wire 17

Archwire hoo ks 18

M etho ds of archwire l igation 20

Awareness of tooth s ize discrepancies 21

Persistence in finishing 21

Ca se SS 22

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INTRODUCTION

FUNDAMENTALS OF TREATMENT

MECHANICS

Andrews published his landmark article' in 1972, and

subsequently designed an appliance based on his findings.

However, soon after the introduction of the preadjusted

appliance, it became clear that the bracket system required a

whole new program of treatment mechanics and force levels

lo fully realize its potential. In turn, the new treatment

mechanics and force levels brought about a need for

modifications to the bracket system. Ultimately, it has

become the mechanics and force levels that have determined

the appliance design, and not vice versa. This chapter reviews

the evolution of orthodontic treatment mechanics since the

early 1970s (the start of the modern era), and goes on to

review the principles of the method currently used.

Appliance design and treatment mechanics are closely

inter-related. To some extent, bracket design can be scientific

and based on research, so that bracket designs can be

produced in a matter of months. However, development and

refinement of ap propriate treatment mechanics take years,

and have to be based on experience with numerous treated

cases. Consequently, the information on treatment mechanics

is often anecdo tal, and based on reco mm end ation s from

experienced clinicia ns. F.ven well-structured investigatio ns

into treatment efficiency tend to be inconclusive.

3

-

3

Orthodontic treatment mechanics are determined by four

elements - bracket selection, bracket positioning, archwire

selection, and force levels (Fig. 1.1). If a balanced

com bina tion of these elements is used, efficient and

systemized treatm ent can b e achieved. However, variation in

one (for example archwire selection) can substantially

influence the other elements and can undermine the

effectiveness of the treatment approach.

/ Bracket

/ selection

\ Bracket

\ posi t ion ing

Archwire \

selection \

Force /

levels /

F i g .

  1 .1 Or th odo n t i c t r ea tm en t mechan ics a re de te rm ined by

fou r e lemen ts .

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THE WORK OF ANDREWS

Andrews is rightly regarded as the father of the preadjusied

bracket system, and it is interesting to review his contribution

in the light of experience over the last 25 years of clinical use.

When the original Straight-Wire Appliance® (SWA) beca me

available in 1972, it was based on science, but included many

of the traditional features of Siamese edgewise brackets.

Andrews' paper was based on the measurement of 120 non-

orthodontic normal cases. He then used the data as a basis to

design a bracket system.

Although the SWA was radically new, traditional heavy

edgewise forces continued to be used. No special anchorage

control measures, such as second order archwire bends, were

employed. This may have been due to his clinical experience

as an edgewise orthodontist and the force levels that were

used. He also emphasized the 'wagon wheel effect' where tip

was lost as torque was added. Hence, he chose to add

additional tip to the anterior brackets. (Fig. 1.2).

Bracket positioning was based on the center of the clinical

crown. Because less wire bendin g was needed with the new

appliance, there was also a trend to standardize arch form. As

a result of Roth's influence, there was a general movement

toward a broad or square arch form, although Andrews

continued to use the basal bone of the mandible as an arch

form reference. Various arch forms were used because no clear

direction w as available.

S W A t i p

R e s e a r c h t i p

2

-  2 " 11° 9

C

  5 " 2 . 8 2 .7 '

!

  8.4" 8.0° 3.6°

SWA tip

1.5" 1.3° 2.5" 0.4" 0.5°

Research t ip

F ig .

  1 .2 The o r i g i na l S t ra igh t -W i re App l i ance® (SWA) was based on mea su remen t o f 120 non -o r th odo n t i c no rm a l cases, a l t ho ugh

ext ra t ip was bu i l t in to the anter ior brackets .

 

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Difficulties were encountered with treatment mechanics in

the early years, clue to the heavy forces and possibly d ue to

the increased tip in the anterior brackets. Consequently,

deepening of the anterior bite, with creation of a lateral open

bite,  was seen in many cases, and this became known as the

'roller coaster' effect (Figs  1.3-1.6).

Fig .

  1.3 In the ear ly years of the p read justed ap pl ianc e, heavy

forces were used, and these wer e associated wi t h de epe ning of

the anter ior b i te and creat ion of a la tera l open b i te which

became known as the ' ro l ler coaster ' e f fect .

i

Fig.  1.4

F i g .  1.5

F i g .

  1.6

Figs. 1.4  to  1.6  The t r ea t me nt sequence above shows t he ' r o l l e r coas t e r' e f f ec t deve lop i ng i n an ear l y t r ea t me nt w i t h t he o r i g i na l

SWA. The un wa nte d dee pe nin g of the o verb i te was due to excess force a nd the use of e last ic ret ra ct io n m echanics.

These early clinical experiences led Andrews to introduce a

series of modifications, and after using the original 'standard'

Straight-Wire Appliance® for a period of time, he

recommended a wide range of brackets. For example, he

determined that for extraction cases, canine brackets with

anti-tip, anti-rotation and power arms were needed (Fig. 1.7).

He also recommended the use of three different sets of incisor

brackets, with varying deg rees of torq ue for different clinical

situations.

\

Wide range

of brackets

Brackets

pos i t ioned a t

the center of the

clin ical crown

\

Various \

a rch forms \

\

eavy force /

levels  j

/

F i g .

  1 .7 Or t ho don t i c t r ea t m en t mechan ics in t he ear l y years o f

t he SWA.

w w w . a l l i s l am. ne t

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THE WORK OF ROTH

Following his ear ly experiences with the or ig ina l SWA, Roth

in t roduc e d me a s u re s to ove rc ome da y - to -da y s ho r t c omings

which he had found in c l in ica l use . Whereas Andrews , wi th

the f i rs t genera t ion of preadjus ted brackets , was

recommending a la rge range of bracket spec if ica t ions , Roth

was anxious to avoid the in vento ry diff icul ties of a m ul t ip le

b rac ket s ys te m. He the refo re re c o mm e nd e d a s ing le a pp l i a nc e

sys tem, cons is t ing primari ly of minimum extrac t ion ser ies

brackets , which he fe l t would a l low him to manage both

extrac t ion and non-extrac t ion cases .

This has been described as the second genera t ion of

p re a d jus t e d b ra c ke t s , a nd R o th ' s r e c omme nda t ions we re

widely accepted by c l in ic ians , some of whom had experienced

s imilar d i ff icul t ies in t rea tment mechanics and were confused

by the wide varie ty of ava i lable brackets . The appl iance

prescript ions developed by Andrews and Roth were based on

the overa ll t rea tm ent me chan ics used in the ir prac t ices .

The R o th t r e a tme n t a pp roa c h e mpha s iz e d the us e o f

ar t icula tors for d iagnos t ic records , for ear ly spl in t

cons truc t ion, and for the cons truc t ion of gnathologica l

pos i t ioners a t the end of t rea tment (Fig . 1 .8) . This approach

was used to a id in es tabl ishing correc t condyle pos i t ion. He

used the center of the c l in ica l c rown for bracket pos i t ioning,

as advo caiec ib y Andrews . As s ta ted abov e , h is a rch form was

wider than Andrews ' in order to avoid damage to canine l ips

du r ing t r e a tme n t a nd to a s s i s t i n ob ta in ing good p ro t rus ive

function.

Bracket posit ioning at

the cent re of the

cl inical crown

Emphasis o n

ar t icu la tors

F i g .  1 . 8 R o t h s e l e c t e d a r a n g e o f b r a c k e t s t o c r e a t e a s i n g l e

a p p l i a n c e s y s t e m .

www.all islam.net  

Problem

s c anned by L I ST t eam

www.allislam.net 

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THE WORK OF MCLAUGHLIN AND

BENNETT BETWEEN 1975 AND 1993

Although they evalua ted many bracket varia t ions , inc luding

(he Andrews ' ' t rans la t io n ' se r ies , in the period 1975 to 199 3

McLaughl in and Bennet t preferred lo work mainly with the

s tandard SWA bracket sys tem. Ins tead of in i t ia l ly m odif ying

the bas ic bracket des ign, for more than 15 years they

developed and ref ined t rea tment mechanics based on s l id ing

mechanics and cont inuous l ight forces , mainly us ing s tandard

SWA brackets . These m echa nics we re pu bl is hed in i t ia l ly as a

series of papers in the early 1990s '

1,51

' an d t hen as a bo ok in

1 9 9 3 '

  ( pi g i 9 )

  a n t

|

  n a v e s e e n

  wide s p re a d a c c e p ta nc e .

T h e i r t r e a t m e n t m e c h a n i c s r e c o m m e n d a t i o n s i n c l u d e d

a c c ura te b ra c ke i pos i t ion ing , a nd l a c e ba c ks a nd be ndba c ks fo r

early anchorage control , wi th l ight a rchwire forces (Fig .  1.10).

S l i d i n g m e c h a n i c s w e r e r e c o m m e n d e d o n . 0 1 9 / . 0 2 5 s t e e l

rec tangu lar wires , wi th l ight .014 f in ishing w ires .

They used the middle of the c l in ica l c rown for bracket

pos i t ion ing du r ing th i s de ve lopme n t pe r iod . A me d ium-s iz e d

s tandard ovoid arch form was used for the majori ty of cases ,

and the s ize re f lec ted the fac t tha t many of the ir pa t ients were

c h i ld re n w i th ma loc dus ions , un l ike Andre ws ' s a mple o f 120

norma l s , wh ic h we re non-e x t ra c t ion a du l t s w i th l a rge a rc he s .

/ Standard

/ SWA bracke t

/ select ion

Brackets

\ posit ion ed at

V the center of the

\ c l inical cro wn

Ovoid \

archwire \

select ion \

Light force  I

levels and sl iding /

mechanics /

^

F i g .

  1.9   Orthodontic Treatment M echanics and the Preadjusted

Appliance   was publ ished in 1993.

F i g .

  1 .1 0  O r t h o d o n t i c t r e a t m e n t m e c ha n ic s e v a l u a t e d b y

M c Lau gh l i n and Benn e t t f r om 1975 to 1993 .

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THE WORK OF MCLAUGHLIN. BENNETT,

AND TREVISI BETWEEN 1993 AND 1997

Having es tabl ished an overa l l approach and a success ful

sys tem of t rea tment mechanics us ing the preadjus ted bracket

sys tem in i ts s tandard form, M cLaughl in a nd B ennet t the n

worked with Trevis i to re -des ign the ent i re bracket sys tem to

c omple me n t the i r p rove n t re a tme n t ph i lo s ophy a nd to

overcome the perce ived inadequacies of the or ig ina l SWA.

They re-examined Andrew s ' or ig ina l f indin gs , and too k in to

account addi t ional research input from Japanese sources

8, 1

'

when des ignin g the MBT™ bracket sys tem .

This th i rd-genera t ion bracket sys tem re ta ined a l l tha t was

bes t in the or ig ina l des ign, but a t the same t ime in t roduced a

ra nge o f improve me n t s a nd s pe c i f i c a tion c ha nge s to ov e rc om e

the c l inica l shor tcom ings . I ts des ign was based on a ba l anc e

of bas ic sc ience and many years of c l in ica l experience . MBT'"

is a version of th e prea dju sted brac ket system specifically for

use with light, co nt in uo us forces , lacebacks an d b end bac ks ,

and i t was des igned to work idea l ly with s l id ing mechanics .

Th e o r ig ina l s yst e m o f do t s a nd d a s he s wa s s upe rs e de d by

la se r nu m be r ing o f s t a nd a rd s i z e me ta l b ra c ke t s , a nd the

re c ta ngu la r s ha pe wa s re p la c e d by the rhomboida l fo rm. Th i s

re duc e d the bu lk o f e a c h b ra c ke t a nd c oo rd in a te d pe rs pe c t ive

l ine s th rough on ly two p la ne s , t he re by a s s i s t ing a c c u ra c y o f

b ra c ke t p l a c e me n t . The b ra c ke t s ys t e m wa s ma de a va i l a b le in

s t a nda rd me ta l (F ig .

  1.11),

  mid-s i z e d , a nd c l e a r fo rms

(Fig.

  1.12).

  It had suff ic ient versa t i l i ty to dea l wi th mos t

c l in ica l s i tua t ions , and to l imit inventory leve ls .

As p re v ious ly s t a t e d (p . 4 ) , t he a n te r io r l i p s pe c i f i c a t ions

for the or ig in a l SWA wer e a ll grea ter tha n th e research

f ind ings . Add i t iona l t i p ba d be e n bu i l t i n , ove r a nd a bove the

s c ien t i fi c me a ns . For e xa m ple , t he im por t a n t u ppe r c a n ine

carri ed 11° in th e first-generation (SWA) an d the n 13° in th e

s e c o n d - g e n e r a t i o n ( R o t h )

1

" s ys t e m, c om pa re d w i th the

research f inding of 8° .

F ig .  1 .11 S tan dard meta l

cont ro l .

MB T ™ b racke ts g ive op t ima l too th F i g .  1 .12 Th is case has C lar i ty™ brackets on the u ppe r a n te r io r

tee th and m id -s ized me ta l b racke ts on the low e r an te r io r tee th .

T he th re e d i f fe ren t b racke t op t ions o f s tanda rd me ta l ,   m i d

s ized meta l and c lear fo rms may be used in combinat ion fo r the

same pa t ien t .

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Additional anterior tip was a disadvantage for three

reasons:

1. It created a significant drain on antero-posterior (A/P)

anchorage.

2.  It increased the tendency to bite dee pening during the

alignment stage.

3.  It brought the upper canine root apex too close to the first

premolar root in some cases.

As lighter forces were being used in all stages of tre atm ent,

this additional 'anti-tip', or second-order com pensa tion, w as

not needed. Therefore, when designing the MBT" bracket

system, it was decided to base the anterior tip on the original

research values. These assisi treatment mech anics becau se they

reduce the anchorage control needs, reduce the tendency to

bite deepening in the early stages of treatment, and put less

demand on patient cooperation. When the original research

values for tip are used for incisors and canines, a total of 10°

less distal root lip in the upper anterior segment and 12° less

distal root lip in the lower anterior segment is needed,

com pared with the original SWA (Pig. 1.13). As the M BT"

measurements are based on Andrews' original research

figures, there is no compromise in ideal static occlusion. And

if the condy les are in centric relation, there is no com prom ise

in ideal functional occlusion as described by Roth.

SWA tip Recommended tip

Fig.  1 .13 The rec om m ende d t i p m e as urem ents f o r t he M BT™ brac k e t s y stem a re bas ed on A ndrew s ' o r i g ina l r es earc h f i gu res , and

these features g ive less d is ta l root t ip in the up pe r and lo we r an ter io r se gments .

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The preadjusted appliance system is a development of the

edgewise bracket, which is relatively inefficient in delivering

torque. When designing the MBT™ bracket system, it was

therefore necessary to build extra torque into the important

incisor and molar regions in order to meet clinical goals in

these areas with a minimum of wire bending (Figs 1.14 &

1.15).

 This design feature helps to overcom e the fund ame ntal

shortcoming of the original edgewise bracket.

Brackets with three options for canine torque were needed

to deal with different patient arch forms and other clinical

variables. Andrews' research finding of-7° torque in the

upper canines, and a reduced torque figure o f- 6 ° (from

-11°) in the lower canines, is satisfactory for the canines in

many cases. I lowever, a typical ortho don tic caseload is a

different sample from the 120 non-extraction adults. Hence

there is a need for three canine torque options.

It was decided that upper canine brackets would be

available with -7°, 0° and +7° torque values in the new

MBT" system, because versatility was needed. The 0" and +7

C

options are preferred for cases with narrow maxillary bone

, Central

F ig .  1.14

-1

 »

  -1°

Original SWA

Recommended torque

F ig .  1.15

Original SWA

-14°

c

Recommended torqu e

10

F igs .  1 .14 and 1 .15 Extra to r que was bu i l t in to the MBT ™ bracket sys tem in the i mp or tan t inc isor and mola r reg ions com par ed

w i th the o r ig ina l S WA .

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form and/or prominent canine roots (Fig. 1.16). Lower canine

torque is -6°, but 0° or even +6° is available for some cases

(Fig.

 1.17),

  if needed.

In the period from 1993 to 1997, McLaughlin and Bennett

also revised their recom me ndations on bracket positioning, to

improve vertical accuracy. In the early years, they had used the

middle of the clinical crown for bracket positioning, but they

subsequently" developed a better system. This accepted the

principles advocated by Andrews, but also used gauges to

ensure greater vertical accuracy (p. 62 ). Their w ork on the

revised bracket designs and the new bracket positioning

technique was incorporated into a second bo ok,

1 2

  published

in 1997 (Fig. 1.18).

F i g .

  1 .16

-7° torque

0" torque

F i g .

  1.17

-§*   torque 0" torque

+7 lorque

+ 6° t o r que

CD

7 3

O

-<

o

-n

-\

m

>

n

>

n

tyi

Figs. 1.16

  and

  1.17

  V e rsa t i l it y w as needed fo r can ine to rqu e , and the re fo re th ree op t ions w e re m ade ava i lab le fo r uppe r and low e r

canines.

Orthodontic

Management of

tfee Dentition with

the ['readjusted

• Appliance

ORTHODONTIC

MANAGEMENT OF

THE DENTITION Wlffl

1HE PREADJUSTED

APPLIANCE

.Win C Iknm-li • Ri.-ta UMaug Wii

KA

 M«*J

/ New range

/ of MBT "*

/ brackets

\ Brackets posit io ned

\ w i t h the he lp

\ of gauges

V^_

Ovoid

archwire \

select ion \

L ight force

levels and sl iding /

mechanics /

^ y

Fig.

  1.18  Orthodontic Manag ement of the Dentition with the

Preadjusted Appliance  was pub lishe d in 1997 an d is sche duled

to be republished in January, 2002.

F i g .  1 .19

  Or th odon t i c t rea tme n t mechan ics deve loped by

McLaugh l in , Bennet t , and Trev is i up to 1997.

11

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THE WORK OF MCLAUGHLIN, BENNETT,

AND TREVISI BETWEEN 1997 AND 2001

In  orde r to c omple te a mode rn s ys t e miz e d me thod o f

t rea tment mechanics , i t became necessary to address the

subjects of archwire selection and force levels .

Al though an ovoid arch form had proved useful in (he

early years , because of prev ious an d cu rrent a rch form

research, i t was rec om me nd ed (Fig . 1 .20) tha t th ree bas ic

shapes of a rch form - tapered, squa re , an d ovoid - w ou ld be

re qu ire d (p . 74 ) . W h e n s upe r im pos e d , t he y va ry ma in ly in

inter-canine and in ter-premolar width , g iving a range of

a pprox ima te ly 6 mm . In t e r -m ola r w id th s o f the th re e s ha pe s

a re qu i t e s imi l ar , bu t t he m o la r a re a s o f w i re s c a n be w id e ne d

or narrowed as needed, by easy wire bending.

R e c omme nda t ions we re pub l i s he d c onc e rn ing a rc h fo rm a nd

archwire se lec t ion.

IS

This th i rd boo k brings a l l (he four t rea tm ent me cha nics

essentials togeth er. I( covers brack et desig n, b rack et

placement , and archwire se lec t ion, and i t re -defines force

le ve l s ( fo r e xa mple lo inc o rpora te re c omme nda t ions fo r the

use of hea t-ac tiva ted nickel- t i tan ium (H A NI ) wires ) , re -s ta t ing

the overal l t rea tment phi loso phy . I t describes a w el l - tes ted

and effec t ive sys tem of t rea tment mechanics for the

preadjus ted appl iance sys tem.

F i g .

  1 .20

  Or th odo n t i c t rea tme n t mechan ics deve loped by

McLa ugh l in , B enn e t t , and T revis i up to 2001 .

12

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OVERVIEW OF THE MB T™ TREATMENT

PHILOSOPHY

The fo llowing e l e me n t s m a ke up the M BT™ t re a tme n t

phi losophy, and in the remainder of th is chapter each wil l be

reviewed in turn:

• Bracket selec tion

• Versatility of the bracket sy stem

• Accuracy of bracket p os i t i oni ng

• Light co nt inu ou s forces

• The .022 versus the .018 s lo t

• Anchorage control ear ly in t rea tm ent

• Group move m e n t

• The use of three arch form s

• On e size of recta ngu lar steel wire

• Archwire ho ok s

• Methods of a rchwire l iga l ion

• Awareness of too th s ize discrepa ncies

• Persistence in finishing

Bracket selection

At the heart of the tech niq ue is a h igh qual i ty , versa t i le

bracket sys tem. A range of s tanda rd me ta l , m id-s ized , a nd

clear brackets is available. The exact bracket specifications are

impor ta n t , a nd a t t e mpts to u s e ' s ome th ing s imi l a r ' c a n

adverse ly affec t the ba lance of the t rea tment mechanics , and

may not produce the des i red t rea tm ent resul t .

The o r thodon t i s t ' s t ime i s t he mo s t va lua b le c omm odi ty in

the or thod ont ic c l in ic . Th ere is a need for the or tho do nt i s t to

have comple te confiden ce in a re l iable bracket sys tem, whic h

gives cons is tent perform ance , and can be used to save

chairside time in the finishing stages of treatment.

Versati l i ty of the bracket system

The sys tem's ful l nam e is MBT™ Versa t i le+ a nd as the na m e

implies,  it  is des igned to be versa t i le , in orde r to dea l wi th

most t rea tment cha l lenges . Th is versa t i li ty (p p 39 -5 1 ) is

useful in both co ntrol l in g invento ry cos ts and avo idin g

needless wire b end ing.

Accuracy of bracket posi t ioning

This is a cor ner s ton e of the t rea tm ent a pp roa ch. Every effort

sho uld be m ad e to ens ure accuracy, an d i t i s par t of the

t e c hn ique to re p os i t ion b ra c ke t s if ne c e s s a ry a s t r e a tme n t

p rog re s s e s. Ga uge s a nd ind iv idua l b ra c ke t -po s i t ion ing c ha r t s

are recommended. In teres t ingly , the search for accuracy has

l e d to a n ups u rge o f r e ne we d in t e re s t i n ind i re c t bond ing

(p .  69) .

Light continuous forces

The t e c hn ique re qu i re s the us e o f l i gh t c on t inuous fo rc e s . The

au tho rs be l ieve th is is the mo s t e ffec tive way to mov e tee th ,

be ing c omfor t a b le fo r the pa t i e n t a nd min im iz in g the th re a t

to anchorage . Light forces a re espec ia l ly important a t the s ta r t

o f t r e a tm e n t , wh e n the b ra c ke t t i p pu t s de m a n d u po n a n le ro -

pos te r io r (A /P) a nc ho ra ge , a nd wh e n it i s im por t a n t t o

mi n im iz e pa t i e n t d i s c omfor t .

I t i s not poss ible to exac t ly quant i fy the te rm ' l ight forces ' .

Trad i t ional ly , forces in the range be low 200 gm were referred

to as light forces, and forces in the range ab ove 6 00 gm w ere

referred to as heavy forces! Esse ntially ther e is a need for the

ort ho do nt i s t to use th in , f lexible wires ear ly on, wi th m inim al

de f l e c t ion , a nd to a vo id too f re que n t a rc hwi re c ha nge s . A l s o ,

the c l in ic ian needs to recognize the s igns of excess force , such

a s t i s sue b l a nc h ing , pa t i e n t d i s c omfor t , a nd u nwa n te d too th

movements (for example rol le r coas ter e ffec t) , and take s teps

to avoid these .

Later in t rea tment , during s l id ing mechanics , l ight

cont inuous forces a re appl ied us ing ac t ive t iebacks and r ig id

.019 / .025 s t e e l work ing w i re s (p . 254) . In the f in i s h ing s t a ge s ,

l ight wires such as .014 s tee l or .016 1IANT are used for

de ta i l i ng o f too th pos i t ions a nd s e t t l i ng .

Alth oug h ' l ight forces ' can not b e define d or quan t i f ied , i t i s

hoped tha t careful s tudy of th is text and the various case

reports wi l l g ive c lear c l in ica l guide l ines on th is subjec t to the

reader .

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33

m

The .022 versus the .018 slot

>

TO

O

<

m

70

<

rn

O

The preadjusted appliance seems to perform best in the .022

form. The larger slot allows more freedom of movement for

the starting wires, and hence helps to keep forces light (Fig.

1.21).

  Later in treatment, the steel rectangular working wires

of .019/.025 have been found to perform well (Fig.  1.22).

With the .018 slot, the main working wire is normally

.016/.022 or .017/.025. These wires are more flexible and

hence show greater deflection and binding during space

closure

14

 with sliding mechanics (p. 259).

n

>

n

1

.018 slot

_ _ _ _ _ _

.022 slot

F i g .  1.21

  The .022 s lo t a l lows mo re f reed om of m ove me nt fo r th e s tar t ing arch w ires , an d th is he lps to keep fo rces l igh t .

.016 x.022

)

+ 4 7 %

— - — " t ^ r r a i

016 / .022

.019/.025

. 019 X .025

F i g .

  1.22

  The .019/.025 s tee l rec tangu lar wor k in g w ires are mo re r ig id than .016/.022 or .017/.025 w ires and pe r fo rm bet te r du r ing

space c losure and overb i te con tro l .

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Anchorage contro l ear ly in t reatment

In the ear ly s tages of t rea tment , the main threa t to anchorage

comes from the inf luence of anter i or brack et t ip . Th e MBT™

brackets have reduced t ip compared with ear l ie r genera t ions

of the preadjus ted ap pl iance . This , com bin ed w ith l ight

archwires , resul ts in reduced anchorage needs in the a l l -

impor t a n t ope n ing s t a ge s o f t r e a tme n t . Or thodon t i s t s who a re

new to the t rea tment approach are of ten surprised by the

reduced demands on anchorage , and gradual ly f ind less need

for t radi t ional headgear , or pa la ta l and l ingual a rches .

Lacebacks (Fig. 1.23) are routinely used to assist control of

canine crowns in prem ola r extrac tion cases , and in so m e n on -

extraction cases.

Bendbacks (Fig . 1 .24) a re used in mos t cases a t the s ta r t of

t rea tment , except where there is a need to increase arch

le ng th . B e ndba c ks e ns u re tha t t he e nds o f the a rc hwi re a re

c omfor t a b le in the mo la r a re a , a nd he lp to p re ve n t me s ia l

mo ve m e n t o f the a n te r io r t e e th , wh ic h i s unde s i ra b le in mo s t

cases except Class 11/2 and some Class III cases. Bendbacks

a nd l a c e ba c ks a re no rm a l ly c on t inue d th rou gho u t too th

level ing and a l igning unt i l the rec tangular s tee l a rchwire s tage .

>

CO

70

O

<

m

70

<

o

"n

-\

70

m

>

n

>

F ig .

  1 .23 Can ine lacebacks are an im por tan t fea tu re o f the MB T

I M

  t re a tm en t ph i los ophy an d are used to assist in con tro l o f can ine

crowns dur ing leve l ing and a l ign ing .

F ig .

  1 .24 Bendbacks he lp to preven t mes ia l mo vem ent o f the ante r io r tee th and ensure com for ta b le p os i t io n ing o f the arch w ire

ends in the molar regions.

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n

Group m ov em en t The use o f t h re e a rch fo r m s

>

CD

73

o

<

m

73

<

o

73

m

>

m

n

i

>

Where poss ible , tee th a re managed in groups ( l - ' ig .  1.25).  In

pre pa ra t ion fo r g roup move me n t in p re mola r e x t ra c t ion c a s e s ,

for example , lacebacks are used to control canines and re t rac t

them suff ic iently to a l low a l ig nm en t of the inc isors . In the

lower a rch, canin es a re re t rac ted with lacebacks unt i l ante r ior

crowding is resolved. After th is , the lower anter ior segment is

ma na ge d   en masse,  as a group of s ix or e ight tee th . In the

upper a rch, canines a re not normal ly re t rac ted away from

la tera l inc isors . How ever , i t i s im po rta nt to m ain ta in a Class I

canine re la t ionship . Therefore , a laceback should be

c on t inue d in the uppe r a rc h to ma in ta in the C la s s I c a n ine

re l a t ions h ip , e ve n i f i t me a ns mov ing the c a n ine a wa y f rom

the lateral incisor (Case JN, p. 1 23 ). It is als o necess ary t o

mo ve the cani ne away from th e la te ra l inc isor in s i tu a t io ns

where a la te ra l inc isor is smal l , and wil l require future bui ld

up ,  and in some cases with a midl ine shif t .

Un t i l t he mid -1 990 s the ovo id a rc h fo rm (p . 76 ) wa s

preferred for mos t of the authors ' cases . They regarded i t as a

re l i a b le fo rm fo r a h igh pe rc e n ta ge o f p re a d jus t e d a pp l i a nc e

cases.

During the la te 1990s , the authors found i t benefic ia l to

us e a t a pe re d a rc h fo rm fo r ma ny c a s e s , a nd s ome t ime s a

s qua re a rc h fo rm. Th e t a pe re d form h a s the na r rowe s t i n t e r -

c a n ine w id t h a nd i s obv ious ly ind ic a te d fo r pa t i e n t s w i th

na r row , t a pe re d a rc h fo rms . The s qua re a rch fo rm i s i nd ic a te d

in cases with broad arch forms and for cases tha t require

buc c a l up r igh t ing o f the lowe r pos te r io r s e gme n t s a nd

e x p a n s i o n o f t h e u p p e r a r c h . C u r r e n t l y , t h e r e c o m m e n d e d

tec hn iqu e is to c rea te an indiv idual i zed form for a ll pa t ien ts ,

ba s e d on the ovo id , t a pe re d , o r s qua re fo rms (pp 78 -79) .

F ig .  1 .25 Wh ere poss ib le, g ro up mo vem ent is carr ied ou t , and the uppe r and lower ant er io r segm ents are ma nag ed as a gr ou p o f

s ix o r e igh t tee t h . In s i tua t ion A , the space has been c losed by mes ia l move me nt o f molars and prem olars - a min i m um anc hora ge

treatm ent . In s i tu a t ion B , the inc isors and can ines have been re t rac te d in t o the ava i lab le space - a max imu m anch orag e s i tu a t io n as

might occur in a Class II I case or a bimaxil lary protrusion case.

16

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One size of rectangular steel wire

Only one size of steel rectangular wire is used in normal

treatment, and this is .019/.025. Larger, full thickness steel

wires have been evaluated, but although they provide greater

control, they are less effective for sliding mechanics.

Occasionally .021/.025 wires in steel or HANT may be

considered in the later stages of treatment, to obtain full

expression of the bracket system. The technique is a 'full arch'

approach, and closing loops (p. 252 ) or sectional wires are

seldom used.

Theoretically, there is approximately 10° of'slop' between

the .019/.025 wire and the .022 slot (Fig. 1.26).  However, in

clinical use the wire performs better than expected, and this is

presumed to be due to residual tip which remains unconecied

at the time of placement of the rectangular wire, and persists

intermittently during treatment as teeth are moved

(Figs 1.26-1.30).

F i g .  1 .26

CO

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Fig. 1.27

F i g .

  1.28

F i g .

  1.29

F i g .

  1.30

Figs 1.26  t o  1.30  The .019/ .025 stee l rec tan gula r w i re pe r forms be t ter th an expe c ted. This is presum ed to be due to res idual t ip a t

the t ime of p lacement of the re c tangu lar w i re , so th at th e torq uin g ef fe c t is prod uced at po ints X and Y.

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Ar c h w i r e h o o k s

The working sieel .019/.02 5 rectangular wires normally have

soldered hooks, and these are useful for many aspects of

treatment mechanics. The average hook positions are

36-38 mm in the upper arch and 26 mm in the lower arch

(Fig.

 1.31).

  There is greater variability of hook position in the

upper arch, and this is assumed to be due to variation in

upper lateral incisor size.

'^o w*Kr^«™l"

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36-38mm

F i g .

  1.31

  The .019/ .025 s tee l rec tangu lar w ire s norma l ly have so ldered hooks in th e pos i t ions show n above. There is g reater

var iab i l i ty o f hook pos i t ion in the upper  arch,  and there for e a w id er rang e o f upper archw ires needs to be s tocked . The arc hwi re

hooks may be used in com bin at io n w i th th e hooks on mo lar tubes or lower second prem olar tube s (p . 52) to add versat i l i ty to the

trea tment mechan ics . Th is versa t i l i ty inc ludes space c losure w i th group movement (A) and ty ing space c losed (B) . Long (C) or shor t

(D) Class II elastics are pos sible , as are Class III (E) and u p- an d- do wn elastics (F). See also Figure s 1.32 to 1.37 op po si te .

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The soldered hooks may be used for space closure during

sliding mechanics (Fig. 1.32) and for h oldin g space closed

(Fig. 1.33).

They are also used to apply (Mass II or (Mass 111  elastics

(Figs 1.34 & 1.35),  or for up-and-down elastics (Fig.  1.36),  or

for short Class II elastics (Fig. 1.37).

F ig .

  1.32  Ac t ive t iebacks are ap pl ied to the so ldered arch wire

hooks to achieve space c losure. In fo rm at io n o n t iebacks is

avai lable on pages 256 to 258.

F i g .

  1.33  A f te r com ple t ion of space c losure, passive t iebacks

are used to preve nt spaces re-op enin g (F ig. 10.10, p . 286) . The

s ec ond p rem o la r has a bon ded tub e (p . 52 ).

« f t § N ^

F ig .

  1.34  Class I I elast ics (Fig. 8.12, p. 225) app l ie d to sold ere d

archwire hooks.

F i g .

  1.35  Class III elastics (Fig . 8. 11 , p. 225 ).

Fig. 1 .36

  Up and do wn e las t ics .

F i g .

  1 .37  Sho r t C lass I I e las t ics f r om a Kobyashi ho ok on the

lower f i rs t premolar .

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Methods of archwire l igat ion

With opening .016 HANTwires the authors favor elastomeric

modules (Figs. 1.38 and 1.39) or ligature ties at the first visit,

as it is not critical to tie the archwire fully into the bracket

slot. At the first adjustment visit it is beneficial to fully tie in

any areas where the wire is not comp letely seated in the

bracket slot.

A similar approach is used at the first and second visits

with rectangular IIANT wires. Any time a 11ANT wire of any

size is not fully engaged it can be helpful to cool the wire

locally to assist full engagement.

The rectangular steel .019/.025 working wires are normally

placed using elastomeric m odules for the first 1 or 2 m on ths.

After that, .010 ligature wires may be used with ligature-tying

pliers or hemostats and ligature directors (Fig. 1.38) to

provide m ore positive archwire engagem ent. This allows the

orthodontist to obtain better expression of the features built

in to the bracket system.

F ig .

  1 .38 Conve nt ional e las tomer ic modules .

F i g .  1 .39 'Easy - to- t ie ' e las tomer ic mod ules .

F i g .

  1 .40 Coon l igature- ty in g p l iers prov ide more p os i t ive

archwire engagement than e las tomer ic modules .

F i g .  1 .41 Hemo s tats or 'mo sq ui to ' p l iers may a lso be used to

app ly w i r e l igatu res to" brackets .

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Awareness of tooth size discrepancies

It is part of the techn ique to assess tooth size at the treatm ent

planning stage and throughout treatment. In recent years,

much more attention has been paid to tooth size

discrepancies, because these can be an ob stacle to ac hieving

an ideal result in m any cases. For example, it is accepted that

enamel reduction among lower incisors is often necessary to

obtain good tooth fit in the Finishing stages as discussed in

Chapter 10.

Persistence in f inishing

Finally, to this chapter, it is worth remembering that

persistence in finishing is needed, despite all the

improvements in bracket design and the better understanding

of treatment mechanics.

In the closing stages of treatment, light wires such as .014

steel are used, and archwire bends are frequently required.

Also, it is necessary to resist the temptation to remove

appliances too early. Tim e should be spent in finishing and

settl ing using techniques recommended in Chapter 10, and

this will be reflected in the Final quality of the result.

REFERENCES

1  Andrews L

 F

 1972 The si x k eys t o no rm a l oc c lus ion . Amer i c an J ou rna l

of Or thodont ics 62:296-307

2 Reukers E 1997 St ra ight W ire Appl ia nce versus con ven t iona l fu l l

edgewise, prospect ive c l inical  t r i a l .  U n i v e rs i t y o f N i jmegen , N i jmegen

3 Reukers H A  J,  Ku i jpers -Jagtm an A M 1996 Ef fec t iveness of

o r t hodon t i c t r ea t men t :  a  prospec t ive c l in ica l  t r ia l .  Eu ropean J ou rna l

of Orthodont ics 18:424 (abstract)

4 M cLaughlin R P, Ben net t J C 1989 The t rans i t ion f ro m s tan dard

edgewise to p readju s ted appl ian ce sys tems. Jou rnal o f C l in ica l

Or thodont ics 23:142-153

5 Bennet t J C, McL augh l in R P 1990 Con t ro l le d space c losure w i t h a

preadjus ted appl iance sys tem . Journa l o f C l in ica l Or t hod ont i cs 24:

251-260

6 M cLaughl in R P, Benn et t J C 1991 Fin ish ing and de ta i l ing w i t h a

preadjus ted appl iance sys tem. Journ al o f C l in ica l O r tho don t ics

25:251-264

7  Benne t t J , Mc Laug h l i n R P 1993 Or t ho don t i c t r ea t me n t mec han ic s

and the preadjus ted a ppl iance . Mosb y-W ol fe , Lond on ( ISBN 0 7235

1906X)

8 Sebata E  1980 An o r t h odo n t i c s t udy o f t ee t h and den t a l a r c h f o rm on

the Japanese normal occ lus ions . The Shikw a Gak uho 80(7) :945-969

9 Wa tan ab e K, Kog a M, Yatab e K, M ot eg i E, I ssh ik i Y A 1996 A

morphomet r i c s t udy on s e t up mode l s o f J apanes e ma loc c lus ions . The

Sh ik w a Gak uho

10 R oth R H 1987 The St ra ight W ire App l ianc e 17 years la ter . Journal o f

C l i n ic a l O r t ho don t i c s 21 : 632 -642

11 M cLa ugh l in R P, Bennet t .  J C 1995 B rac k e t p l ac emen t w i t h t h e

p read jus t ed ap p l i anc e . J ou rna l o f C l i n ic a l O r t hod on t i c s 29 : 302 -311

12 Benne t t J , Mc La ugh l i n R p 1997 Or t h odo n t i c m anag em en t o f t h e

den t i t i on w i t h t he p read jus t ed app l i anc e . I s i s Med i c a l Med ia , Ox f o rd

( ISBN 1 899066 91 8) . Republ ish ed in 2002 by Mosb y . Edin burg h

(ISBN 07234 32651)

13 Mc La ugh l i n R P, Benne t t J C 1999 A rc h f o rm c ons ide ra t i ons f o r

s tab i l i t y a nd es thet ics . Rev is ta Espana Or tod ont ica 29(2) :46-63

14 O uchi K, Koga M, Wat ana be K, Iss ik i Y, Kawa da  E 2001 The e f f ea s o f

re t rac t i on f o r c es app l i ed t o t he an t e r i o r s egmen t on o r t hod on t i c a r c h

w i res - c hanges i n w i re de f l ec t i on w i t h w i re  s ize.  Presented to

s ou t he rn C a l i f o rn ia c om pone n t o f Edw ard H Ang le Soc ie t y .  In   press.

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CASE SS

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m

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x

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n

A s ho r t ove rv ie w o f a non -e x t ra c t io n C la s s I c a s e . Fu l l e r

d e t a i l s o f t r e a t m e n t m e c h a n i c s a r e i n c l u d e d i n C h a p t e r s 4

to 10.

A female pa t ie nt , aged 10.5 years , wi th MM angle of 30 ° an d

s l ight ly re t roc l ined upper and lower inc isors . At the s ta r t of

t r e a tme n t , t he re wa s mi ld a n te r io r c rowding wi th s o me

ro ta t ions .

Du ring (o olh leve l ing, the MBT™ ph i lo sop hy involves l ight

fo rc e s w i th a pp ropr i a t e a nc hora ge s uppor t f rom l a c e ba c ks o r

bendbacks . Anchorage support f rom pala ta l or l ingual bars

a nd /o r he a dg e a r is u s e d whe re a pp r opr i a t e . M ul t i s t r a nd o r

rou nd s tee l and r ou nd or rec tangu lar HANT wires a re used.

The .022 s lo t i s preferred, and a range of s tandard meta l , mid

s ized meta l , and c lear brackets is ava i lable as a coordina ted

sys tem. Here , accura te ly pos i t ioned mid-s ized meta l brackets

a nd .016 round HANT wire s a re in p l a c e , w i th be nd ba c k s .

Lacebacks are used mainly in premolar extrac t ion cases , and

were not ne eded in th is case . Grea t im po rtan ce is g iven to

accuracy of bracket pos i t ioning.

Th e ph i lo so ph y recognizes three arch forms , and the need for

individual iza t ion. After tooth leve l ing and a l igning, s tee l

re c t a ngu la r .0 19 /0 25 wi re s a re u s e d to c om ple te a rc h l e ve ling

and overbi te control , to correc t A/P discrepancies and torque ,

and to c lose spaces where necessary . Here , rec tangular s tee l

wires wi th pass ive t iebacks are in p lace (Fig

  1.47).

Se t t l i ng t e c hn ique s a re u s e d fo r one to two mon ths p r io r to

debanding in the majori ty of cases (Fig  1.48).

The case after 1 m on th of settl ing (Fig  1.49).

The case afte r appl i anc e rem oval (Fig  1.50).

Lowe r c a n ine - to -c a n ine bonde d re t a ine rs a re u s e d fo r mos t

cases , wi th up pe r remo vab le re tent ion (see Ch . 11) . Pos t-

t r e a tme n t l e t te r s (p . 316 ) a re re c o mm e nd e d to e nc oura ge

good c oope ra t ion w i th the imp or t a n t r e t e n t ion pha s e .

Fig. 1.42

F i g .

  1.45

F i g .

  1.48

22

F i g .

  1.51

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T . S .

 B e g i n n i n g

1 0 . 5 y e a r s

9/23794

F i g .

  1.43

S N A

S N B

A N B

A -N

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  FH

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M M

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1

  to

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1  to Max P lane

1  to  Mand P lane

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0  mm

3 3 °

3 0 °

• 30 °

3  mm

0

  mm

1 0 3 °

8 0 °

TO

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F i g .  1.50

F i g .  1.52

SN A  /  8 3

S N B

A N B

A -N

  FH

Po-N

  FH

W I TS

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M M

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1  to  A-Po

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m m

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F i g .

  1.53

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CHAPTER 2

o  n o o o n w a w t s a a M a B w e e i i i i  n n nn m i n i1 1 ' l i t g a g g a a w g a M B W — — — — — —

Appl iance speci f icat ions - var iat ions

and versat i l i ty

Introduction 27

Design features of a  modern bracket system

  28

Range of brackets 28

Rhomboidal shap e 29

Torque in base - the CAD factor 30

In-out specification 31

Expression of in -o ut 31

Upper second premo lars 31

Tip specification 32

Expression of tip 32

Torque specification

  3 3

Expression of to rq ue 33

Incisor torq ue 34

Canine torqu e 36

Upper premo lar and mo lar torqu e 37

Lower premolar and mo lar torqu e 38

The versatility of the bracket system 39

Aspec ts of versatility 39

Palatally displa ced up per lateral incisors 40

Three torqu e op t ion s for the up per canines 44

Three torqu e op t ion s for the lower canine s 44

When should the three canine opt ions

be used? 44

Interch ange able lowe r incisor brackets 48

Interchangeable

  upper

  prem olar brackets 49

Use of upper second molar tubes on f i rs t molars

in non -HG cases 50

Use of lower second molar tubes on upper molars

in Class II mo lar relatio nship s 51

Additional bracket and tube op tion s 52

Bracket for sma ll up pe r secon d pre mo lars 52

Lower second prem olar tubes 52

Lower first mo lar non -con vertib le tub es 53

Lower first molar double tube and upper first

molar

  tr iple tube at tach me nts 53

Bon dable mini second mo lar tubes 54

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INTRODUCTION

— — M — — — — — — — W — — ■ » — W M l — I I W l I ' l l l l-'—i-l'.-*  III

  —111

 1 riTl3«

It has been sa id tha t m edica l an d den ta l t r ea tm ent is based

equal ly on sc ience , t radi t ion, and c l in ica l experience . When

th e  origina l SWA be cam e avai lable in 197 2, i t wa s based on

sc ience , but inc luded many of the t radi t ional fea tures of

Siamese edgewise brackets . I t was radica l ly new and therefore

there was no inp ut from c l in ica l exper ience . Andr ew s ' had

me a s u red 120 non -o r t hod on t i c no rm a l ca s e s a nd the n us e d

the da ta , wi th som e changes , to prod uce a bracket sys tem .

l l is a lmo s t 3 0 years s ince the or ig ina l SWA was re leased.

The sc ience and t rad i t ion w hich wen t in to the or ig ina l d es ign

are now balanced by a weal th of c l in ica l experience . The

authors have a lso re-examined Andrews ' or ig ina l f indings , and

in t roduc e d a dd i t iona l r e s e a rc h inpu t f rom J a pa ne s e s ou rc e s ,

2 , 3

to update the sc ient i f ic input .

Prom an early s tage , the authors avoided the t radi t ional

heavy edgewise forces and they developed a t rea tment sys tem

based on s l id ing mechanics and l ight cont inuous forces ,

which has seen widesp read ac cepta nce . They dev elope d a

third genera t ion of brackets to fol low the Andrews (f i rs t -

ge ne ra t ion ) a nd R o th ( s e c ond-ge ne ra t ion ) a pp l i a nc e s , on the

bas is tha t the prov en me chan ics and force levels sho uld

determine the des ign of the new bracket sys tem, and not v ice

versa.

The MBT™ Ver sa t i le+ brack et sys tem m ain ta in s a l l tha t

was bes t in the or ig ina l des ign, but a t the same t ime a range

of improvements and spec if ica t ion changes have been

introduced to overcome the c l in ica l shortcomings . I t i s based

on a ba lanced mix of sc ience , t radi t ion, and experience . The

a pp l ia nc e i s r e c o mm e nde d a s a mod e m ve rs ion o f the

preadjus ted bracket sys tem for use with l ight c on t in uo us

forces , lacebacks , and bendbacks . I t was des igned to work

idea l ly with s l id ing mechanics .

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DESIGN FEATURES OF A MODERN

BRACKET SYSTEM

Range o f b racke t s

The baseline of expectation concerning orthodontic brackets

has risen consider ably since th e original SWA was released in

the 1970s. The modern orthodontist expects to have three

main bracket systems available to meet the needs of a typical

caseload:

• Standard size metal brackets - where control is the main

requirem ent (Fig. 2.1).

• Mid-size metal brackets - th ese give less control, bu t are

useful for cases with average to small teeth, where there is

poor oral hygiene, or where control needs are modest

(Fig. 2.2) . "

• Esthetic brackets - the se will be neede d for older patien ts,

where a m etal appearance is not accep table (Fig. 2.3).

These are general developments in orthodontic bracket

technology. They are not specific to the preadjusted system,

but they are changes which were incorporated into the new

concept.

The original i .d. system of dots and dashes has been

superseded by laser numbering of standard size metal

brackets (Figs 2.1 , 2.4 & 2.5). This feature can not be carried

through into mid-size brackets, owing to their smaller size,

and it is technically not possible with clear brackets. So for

these groups of brackets, a more conve ntional i .d. system of

colored dots continues to be used.

F i g .

  2 .1 S tanda rd s ize meta l b rackets .

F i g .

  2 .2 Mid-s ize meta l b rackets .

28

F i g .

  2 .3 Esthet ic C lar i ty™ brackets .

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Rhomboidal shape

The original rectangular shape of the standard metal SWA

(Fig. 2.4) has been supe rseded by the rhom bo ida l form

(Fig. 2.5).

This reduces the bulk of each bracket and allows reference

lines in both the horizontal and the vertical planes, thereby

assisting accuracy of bracket place me nt.

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1/1

F ig .

  2 .4 The or ig in a l s tandard m eta l SWA brackets we re

rectangular in shape, and the i.d. system was based on dots in

the upper arch and dashes in the lower   arch.

F i g .

  2 .5 Brackets o f a rho mb oid a l shape have reduced bu lk an d

the re i s coo rd ina t ion o f pe rspec t ive l ines th r ou gh on ly tw o

planes, which assists in accuracy of bracket placement.

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Torque in base - th e com pu te r -a ided

des ign (CAD) fac tor

Torqu e-in-base was an im por tant is sue with the f irst - and

second-genera t ion preadjus ted brackets , because leve l s lo t

l ine-up was not poss ible wi th brackets des igned with torque-

in-face . Tech nolog y w as not av a i lable to se t bracket s lo ts in

the correct position relative to the facial surfaces of the crowns

wi thou t to rque - in -ba s e . M ode rn b ra c ke t s ys t e ms , i nc lud ing

the M BT™ s ys te m, ha ve be e n de ve lope d us ing c om pu te r -

a ide d de s ign a nd c ompu te r -a ide d ma c h in ing - t he C AD-C AM

system. This a l low s m ore f lexibi l ity of des ign , not o nly to

place the s lo ts in the correc t pos i t ion in the brackets , but a lso

to enhance bracket s t rength and fea tures such as depth of t ie

wing and lah io-l ingual profi le . The co mp ute r is f irst able to

locate the precise location for the bracket slot, relative to

in -o u t d i s t a nc e a nd to rque pos i t io n fo r e a c h too th . On c e th i s

pos i t ion is es tabl ished , i t can then bui ld up t he ' in-f i ll ' a reas

to opt imize a l l requirements of the brackets (Figs 2 .6-2 .8) .

The brackets may be finished with all torque-in-base (full

s i ze a nd c l e a r ) o r w i th a c om bin a t io n o f to rque - in -b a s e a nd

torque-in-face (mid-s ize) wi th absolute ly no difference in s lo t

pos i t ion. Since the advent of CAD-CAM bracket des ign, i t i s

not necessary to d iscuss th is h is tor ica l i s sue any longer!

F ig 2 .6 B rack e ts w i t h t o rqu e i n base w e re des igned s o t ha t t h e

LA po in t , t he bas e po in t , and the s lo t po in t w ere on the s am e

hor izonta l p lane. To accompl ish th is an acute (<90°) angle was

req ui re d at the occ lusal aspec t o f th e brack et base, an d an

obtuse (>90°) angle at the g ing iva l aspec t o f the bracket base.

F ig 2.7 The CAD sys tem analyzes the id eal s lo t locat ion a nd

then des igns the in- f i l l o f the bracket as necessary .

F ig 2 .8 The ou tc o m e o f t he C AD p roc ess is t h a t t he res u l t i ng

bracke t can have to rq ue in base, to rq ue in face, or a

c o m b i n a t i o n o f t h e t w o .

30

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IN-OUT SPECIFICATION

Expression of in-out

The in-out feature of preadjusted brackets is 100% fully

expressed, because the archwire lies snugly in the slot. The

jabio-lingual movement is rapid, and normally occurs in one

visit. The original SWA in -o ut specification was therefore

used as a basis when designing the MBT

IM

  system.

Upper second premolars

Andrews' 120 research normals all had teeth with full-size

crowns in the labio-lingual dimension, but in clinical practice

upper second premolars have small crowns in approximately

20%

  of cases. An alternative bracket, which is 0.5mm thicker

than normal, is useful for such teeth (Figs 2.9-2.11), This

feature is helpful in obtaining good alignment of marginal

ridges in cases with small u pper second premo lars and is

discussed on page 52. For cases with upper first and second

premo lars of the same size, the upper first premolar bracket is

used for both teeth. Only a small inventory of upper second

premolar brackets is required, and this should be monitored

by one staff mem ber.

>

"D

"D

( ^

>

n

m

CO

-Q

m

Q

n

>

H

O

Fig.

 2.9 This case has small up pe r second pre mo lars.

F i g .  2 . 1 0

  A p rem o la r b rac k e t w h ic h is 0 .5m m th i c k e r t h an

norm a l i s us e fu l f o r s m a l l upper s ec ond p rem o la r s .

Normal

bracket

0.5 mm thicker

bracket

Fig.

  2.11  App rox im ate ly 2 0% of cases have uppe r second prem olars w i t h smal l c l in ica l c rown s , an d a bracke t wh ich is 0 .5mm th icke r

is he lp fu l in ob ta in ing go od a l i g nm e n t o f m a rg ina l r i dges w i t h ou t w i r e be nd in g fo r t hes e c as es .

31

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NJ

TIP SPECIFICATION

Express ion o f t ip

>

n

m

t / i

T3

m

n

%

O

-z.

50 Qc

  0

F i g .  2 .12

  R e c o m m e n d e d t i p .

The tip feature of preadjusted brackets is almost fully

expressed. A .019/.025 wire in an upp er ca nine bracket with

8" of built-in tip will express most of that tip. More than 7°

of the 8° will be fully expressed (Fig. 2.13). With light

continuous force mechanics, tip can be well controlled, and

tip specifications are fully and rapidly expressed in clinical

use. The research figures for tip were closely adhered to when

the MBT™ bracket system was designed, although small

changes were made to the tip specification for molar and

upper premolar at tachm ents.

For all molars, a 0° tip bracket is recom me nded . If placed

parallel to the buccal cusps of the molars, a 0° lip bracket will

deliver 5° of tip for the uppers and 2° of tip for the lowers

(Fig. 2.14). This issue has been discussed at length elsewhere,

and the reader is referred to other lexts for more detailed

information.'

1

For the upper premolars, the authors prefer brackets with

0° of  tip,  com pare d with 2° in the original SWA. This places

the crowns of these teeth in a slightly more upright position,

more in the direction of Class I. It also reduces anchorage

needs in som e cases. The 2° may seem insignificant, b ut th e

total of 8° from the four upper premolars does become

significant in anchorage terms. For the lower pre molars, the

2° of mesial crown tip in the original SWA brackets works

well, keeping the crowns inclined forwards in a Class I

direction, and continues to be used and recommended.

Less

than 1°

(

i

N

.

...\  \ \\

.019/.025

\\:A   H ]

Less

than 1°

F i g .

  2 . 1 3  The t i p f e a tu r e o f p read jus ted b rac k e ts is a lm os t f u l l y

expressed,

  an d the re is less tha n 1° of ' s lo p ' whe n a .019 / .025

rec ta ngu lar w i re is p laced .

F i g .  2 . 1 4  U p p e r a n d l o w e r m o l a r a t t a c h m e n t s h a v e 0 " t i p .

W he n p laced para l le l to th e buccal cusps of th e molars , th is

del ivers 5° of t ip in the u ppers and 2° of t ip in the lowers .

32

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TORQUE SPECIFICATION

N)

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>

T3

■ o

>

n

m

T3

m

n

n

>

o

+7° 0° -7°

-14

-7°

Molars

Premolars Canines

- 1 7

r

Central

incisors

+6° 0° - 6

-12"

F ig .

  2.15  R ec om m en ded to rque s pec i f i ca t i ons

Expression of torque

As

  discussed above, in-out and tip features are efficiently

expressed by the preadjusted appliance system. In contrast,

torque is not efficiently expressed, owing to two mechanical

reasons:

• The area of torque application is small, and dep end s on

the twist effect of a relatively sm all wire, com pare d with

the bulk of the tooth (Fig. 2.16).

In order to slide teeth, it is normal practice to use

.019/.025 steel wires in a .022 slot, because a full-thickness

wire prevents sliding. These wires have 'slop ' of about 10°,

depending on the tolerances in bracket and wire

manufacturing, and the amount of wire edge 'rounding' or

'radiusing' (Fig. 2.17).

F ig .  2 .16

  Torq ue is no t e f f ic ient ly expressed by the prea djus te d

appl iance sys tem, par t ly due to the smal l area of torque

appl icat ion.

F i g .  2 .1 7

  A rec tan gula r .019/ .025 s tee l w i re in .022 s lo t w i l l

have app rox im ate ly 10" of ' s lop ' . The exac t am ou nt dep ends on

the p rec i s ion o f m anu fac tu re o f t he w i re and b rac k e t s lo t and

t h e a m o u n t o f w i r e e d g e ' r o u n d i n g ' o r ' r a d i u s i n g '.

33

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M

As a result of the relative inefficiency of preadj listed

bending. Arch form factors, together with canine prominence

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>

"O

>

n

m

i/>

-u

m

Q

-n

n

o

z

brackets in delivering torc|ue, it was necessary to build extra

torque into the incisor, molar, and lower premolar brackets,

in order to meet clinical goals with a minimum of wire

Incisor torque

It is helpful clinically to have torque control (Figs 2.18-2.21)

which moves upper incisor roots palatally and lower incisor

roots labially. This treatment requirement is necessary for

many types of malocclusion:

• Class II cases, where Class II elastics can cau se torq ue to be

'lost' on the upper incisors, and where lower incisors tend

to procline during leveling and in response to Class II

elastics.

• Class I cases, whe re correct incisor torque helps to achieve

good anterior tooth fit.

and other issues, made it necessary to have brackets with

three options for canine torque, as discussed on pages 44

to 48.

F i g .

  2 . 1 8

  Uppe r cent ra l inc isor bracke t .

Class III cases, where correct torque can help to

compensate for mild Class III dental bases.

F i g .  2 . 1 9  Upp er la tera l inc isor brac ket .

F i g .

  2 . 2 0

  Lower inc isor bracket .

34

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Because of these frequent clinical requirements, there is

Is)

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generally a need for greater palatal root torque of the upper

incisors and for more labial root torque of the lower incisors.

For these reasons, the authors rec omm end +17° of torque for

the upper central incisors, +10° of torque for the upper lateral

incisors, and -6° of torque for the lower incisors (Fig. 2.21).

La te ra

inc isors

C e n t r a l

inc isors

L a t e r a

inc isors

r i / -1 °

O r i g i n a l S W A

- 6 ° * \ - / - 6 "

R e c o m m e n d e d

>

n

m

v-i

"O

m

n

n

>

H

O

Fig.

 2 .21  The au tho rs r ec om m en d + 17° o f t o rq ue fo r t h e upper c en t ra l inc i so r , + 10° o f t o rq ue fo r t he up per l a te ra l i nc is o rs , an d -6 °

of torque for the low er inc isors to ass is t in mo vem en t of up pe r inc isor roots pa lata l ly and low er inc isor roots lab ia l ly .

3 5

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Canine torque

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Andrews' 120 non-orthodontic normals were non-extraction

adults. However, a typical orlhodontic caseload is a different

sample. The finding o f- 7 ° torque for the uppe r canines has

proved to be satisfactory for m ost cases, but the o riginal SWA

value of

 -11 °

 torque for the lower canines has not been

satisfactory, as it tends to leave the lower canine roots in a

prom inen t po sition in most cases. Versatility is needed for

canine torque values. A range of -7 ° , 0° an d +7° torque,is

therefore available for the upper canine s (Pigs 2.22 & 2.23)

an d - 6 ° , 0° , an d + 6° for lower canines (Figs 2.24 & 2.25), as

described on pages 44 and 45.

F ig .  2 .22 The upper c an ine b rac k e t has -7 ° t o r qu e . W hen

inver ted i t has +7° torque.

F i g .  2 .23 The upper c an ine b rac k e t w i t h ho ok has 0° t o r qu e .

F ig .  2 .24 The l ow er c an ine b rac k e t has -6 ° t o rq ue . Wh en

inver ted i t has +6° torque.

F i g .  2 .25 The l ow er c an ine b rac k e t w i t h h ook has 0° t o r qu e .

36

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Upper premolar and molar torque

M

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The upper premolar torque value of -7° has proven to be

satisfactory in clinical use, and the authors continue to work

with it.

For upper molars, on the other hand, the -9° of the

original SWA has proven to be inadequate, and they prefer

-14° ,  as this gives better control of the palatal cusps (Fig.

2.26). The -1 4° specification for the uppe r m olars helps to

reduce interferences during function, by preventing the palatal

cusps from hanging dow n. It is imp ortant to have a

sufficiently wide maxilla to allow this torque change. If not,

cortical plate interference prevents achievement of correct

torque.

>

n

m

t o

-o

m

n

n

>

H

o

F i g .  2 . 2 7  Upper second mola r tub e.

-14'

o

Original SWA

Recommended

Fig.

 2 .26

  U pper mo la r a t tachmen ts w i th -14 ° o f to rq ue g ive

better control of the palatal cusps.

F i g .

  2 . 2 8

  Upper fi rs t mo la r tub e.

F i g .

  2 . 2 9

  Upper f i rs t and second prem olar b racket .

37

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NJ

Lower premolar and molar torque

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>

r-

>

n

m

1/1

"0

m

n

n

>

H

O

z

1/1

Many orthodontic cases have narrow maxillary arches, with

the lower arches showing a com pensa ting narrowing. These

cases normally require buccal crown torque (uprighting) of

the lower molars and prem olars. Also, the original SWA first

molar torque (-30°) and second molar torque (-35°)

specifications allowed 'rolling-in' of lower molars. Therefore

the authors have made the important decision to change

lower premolar torque by 5°, first molar torque by 10°, and

second molar torque by 25° (Fig. 2.30).

F i g .

  2 .3 0

  The authors have reco mm end ed substant ia l changes

in to rque fea tures fo r the a t tachments in the lower bucca l

segments , comp ared w i t h the or ig i na l SW A. Th is reduces the

' ro l l ing- in '

  of lo wer molars as we ll as assist ing in th e

deve lopmen t o f the mand ibu la r

  arch.

Original SWA Recommended

38

F i g .  2 .3 1  Lower f i rs t p rem olar b rack et . F i g .  2 . 3 2  Lower second prem olar b rac ket .

* * " . &

F i g .  2 .3 3

  Lower f i rs t mo la r conver t ib le bucca l tu be .

F i g .  2 .3 4

  Lower second mola r tub e.

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THE VERSATILITY OF  THE BRACKET

SYSTEM

M

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The firsl

 and

  s e c ond ge ne ra t ion

 (p. 6) of

 bra c ke t s

 and

  buccal

tubes

 had a

 s ing le op t io n

  for

  each spec if ic tooth , wi th

  a

re c omme nda t ion

  for

  p r o p e r

  tip,

 t o r q u e

  and

  i n - o u t

c ompe ns a t ion . The re

 was

  l i t t le room

  for

 v ersa t i l i ty .

 The

MBT™ Versa t i le+ bracket s ys tem

  has

 overa l l de s ign

improve me n t s c ompa re d w i th p re v ious a pp l i a nc e s . The s e

inc lude chang es in tip and  t o r q u e ,  as well  as  des ign fea tures

which in t roduce

 a new

 charac ter is t ic

  for the

  pre a d jus t e d

system

  -

  tha t

 of

  versatility.

As de s c r ibe d b e low,  the  innov a t ion inc o rpora te s s e ve n

different bracket

  and

  buc c a l t ube pos s ib i l i t i e s , de pe nd ing

  on

t h e n e e d s

 of the

 case . This c rea tes

 a

  pla tform

  for the

  archwires

a n d

  the

  bracket sys tem

  to

  p r o d u c e

  the

  necessary

i n d i v i d u a l i z a t i o n

  an d

  ove rc o r re c t ion

  for

  certa in types

  of

  case.

The be ne f i t

  can

  a p p l y

  to

  ind iv idua l t e e th

  or to

  g r o u p s

 of

t e e th ,

  in

  s ome ins t a nc e s . Th i s r e duc e s

  the

  ne e d

  for

  first-,

s e c o n d -

  an d

  th i rd -o rde r be nds l a t e r

  in

  t re a tme n t ,

  and

improves eff ic iency.

Aspects of versatility

Seven main areas

 of

 v ersa t i l i ty

 are

  l is ted be low,

  an d

  they will

  be

  reviewed

  in

  turn:

1 . Opt ions  for  pala ta l ly d isplaced up per la te ral inc isors (- 10 °) .

2 .

  Thre e to rque op t ions for the  u p p e r c a n i n e s  (- 7° , 0° , and +7°).

3 .  Thre e to rque op t ions

  for

  lowe r c a n ine s

  (- 6° , 0 , and +6 ).

4 .  Interchangeable lower inc isor brackets

  - the

  s a m e

 tip and

  to rque .

5.  In te rc ha nge a b le uppe r p re mola r b ra c ke t s

  - the

 s a m e

 tip and

  to rque .

6.

  Use of

 upp e r s e c ond m ola r tube s

  on

  fi rs t molars

  in

  non-1

 IC

 cases.

7.

  Use of

  lowe r s e c ond mola r tube s

  for the

  upper f i rs t

  and

  s e c o n d m o l a r s

  of the

  oppos i t e s ide ,

when finishing cases

  to a

  Class

  II

  mola r r e l a t ions h ip .

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39

'.allislam.net 

.

NJ

Palataliy displaced upper lateral incisors

The orthodontist is often called upon to correct upper lateral

A convenient way to m anage these cases involves the

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>

■ D

r;

>

Z

n

m

<

>

E E

§

O

z

>

z

a<

m

33

>

incisors which are palataliy displaced. Cases with upper

anterior crowding on Class

 1

  or Class III dental bases are

liable to have upper lateral incisors which are in crossbile,

and it can be difficult to achieve stable root correction. There

is a risk of moving the crown labially, while leaving the root

palataliy placed. In this situation, there will be a need for

additional wire bending, and treatment time will be extended.

following procedures:

• Du ring the alignm ent stage, il is necessary to create enoug h

space for the palataliy displaced tooth. This is achieved

using coil spring. The brackets on the adjacent teeth are

lied with wire ligatures, to prevent rotations (figs 2.35 &

2.36).

-<

F i g .

  2 .35  I t is necessary to cre ate su ff ic ie nt space fo r p ala tal iy

d i sp laced inc is o rs be fo re a t t e m p t ing t o m ov e the m lab ia l l y .

Bendbacks are p laced 2 mm dis ta l to m olar tube s , to a l lo w an

increase in arch length.

F i g .  2 .3 6

  A f t er c re at ion of space, a .015 mu l t is t r an d w i re or a

.016 HANT wi re may be used to gent ly move the la tera l inc isors

labially.

40

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• The palatally displaced lateral incisor is bracketed with the

normal bracket, but it is rotated 180° (Figs 2.37

 

2.38),

which changes the torque from +10° to -10°. This assists

in labial root torque at the rectangular wire stage. The tip

stays the same at 8 °. The left side bracket is placed on the

Fig.  2 .37 Conve nt ional p lacem ent of an upper la te ra l inc isor

bracket gives +10° of torque.

left incisor and the right side bracket is placed on the right

incisor. This is mentioned because it is a frequently asked

question! It is not correct to place the left incisor bracket

on the right incisor or vice versa.

-10° 17°

Lateral  |  J  \ I Centra

incisor  ' -

/J

  \—/ incisor

Rotated 180'

F i g .  2 .3 8 Ro tat ion o f th e la tera l incisor bracke t by 180°

c hanges the t o rque f r om + 10° t o - 10° .

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In the following treatment sequence, the use of coil spring

is shown, as a method of re-creating space to allow alignment

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of

 a

  paiatally displaced upper lateral incisor. The coil spring

was re-activated by using a split round tube (517-620 3M

Unitek).

F i g .

  2 . 3 9 A

  A dec is ion was made to ex t ra c t upp er f i r s t

p remolars and lower second premolars in th is c rowded Class I

case w i t h a pa ia ta l l y d isp laced upp er r ig h t la te ra l inc isor an d an

upper m id l ine sh i f t to the r igh t . Af te r in i t ia l leve l ing and

a l ign ing , a co i l sp r ing was p laced to c rea te space fo r the la te ra l

inc isor . The lower a rch b racke ts were no t p laced a t th is s tage,

because a lower acryl ic spl int was l ikely to be needed later in

t h e t r e a t m e n t .

F i g .  2 . 3 9 C

  Here a sp l i t round tu be has been p laced on to th e

arch wi re t o reac t iva te the co il spr ing . I t is the re fo re no t

necessary to remove the a rchwi re to reac t iva te . Teeth ad jacent

to the co i l spr ing a lways need to be t ied wi th w i re l iga tu res , to

p r e ve n t u n wa n t e d r o t a t i o n s .

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F i g .  2 . 3 9 B

  The case 1 m on th a f te r F igure 2 .39A. Space-ope n ing

procedures o f th is type shou ld be car r ied ou t on .018 round

stee l w i res o r heav ie r w i res . A sec t ion o f c losed co i l spr ing is

be ing used wi th the cen ter par t s t re tched to ac t iva te . By us ing

c losed co i l spr ing in th is way , there is norm al ly n o t a p rob lem

wi t h sh a r p e n d s , a s ca n h a p p e n w i t h o p e n co i l sp r i n g . M o d u le s

h a ve b e e n r e m o ve d r e a d y f o r a d ju s t m e n t a n d r e a c t i va t i o n .

F i g .  2 . 3 9 D

  Mod u les have been p laced, and the pa t ien t w i l l be

seen aga in in 4 weeks. The co i l spr ing wi l l re -c rea te space fo r

the la te ra l inc isor and he lp to res to re the mid l ines .

In the following treatment sequence, the correction of a

palatally displaced upper lateral incisor is shown.

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Fig . 2 . 4 0 A  Th is non -ex t ra c t ion case presented w i th an upper

left lateral inc isor in crossbite.

F i g . 2.40C  Rec tangular s tee l .019/ .025 wo rk i ng w i res are in

place.

 No ad di t io na l w i re b end ing was requi re d in th is case.

F i g .  2 . 4 0 B  Ope n co i l spr ing is be i ng used to c reate space fo r

the la tera l inc isor (p . 40) befor e an at te mp t is mad e to move i t

lab ia l ly . Teeth adjacent to the co i l spr ing are t ied w i th w i re. The

upp er le f t la tera l inc isor bracket is ro t ate d 180" .

F i g .  2 . 4 0 D  The case af ter appl iance re mo val .

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T h r e e t o r q u e o p t i o n s f o r t h e u p p e r

can ines ( -7° , 0 ° ,  +7°)

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Effective torque c ontrol of th e upp er ca nines is necessary,

because they are key elements in a mutually protected

occlusion. The goal is to deliver ideal tip an d torque to the

canin es, so that they can fulfil thei r role in lateral exc ursion s,

and have a small amo unt of lateral freedom in maxim um

inter-cuspation.

The inefficiency of the preadjusted appliance in delivering

torque is evident when working with canines, because they

are the teeth With the longest roots in the h um an dentition.

There will be less wire bending required if a correct selection

is ma de from the three torque option s which are available.

The MBT™ philosophy uses two types of upper cuspid

bracket (Fig. 2.41) to provide three possible torque optio ns

-7 "

 torque 0° torque +7° torque

F i g .  2 . 4 1  The M BT™ ph i l os ophy has th re e to r qu e op t i ons f o r

t he upper  arch.

-<

T h r e e t o r q u e o p t i o n s  f o r t h e  l o w e r

can ines ( -6° ,  0° ,  +6°)

The original SWA value of -11 ° torque

4

 was not

satisfactory, as it tended to leave the lower canine roots too

prom inent in som e cases. The authors prefer - 6° lower canine

torque, but for som e cases they may use 0° or even +6° . They

favor reduced lower canine torque, compared with the

research findings, because lower canine roots some times s how

gingival recession, and benefit from being moved into

alveolar bo ne. Also, in som e d eep b ite cases, it is necessary to

torque the canine crown labially and at the same time

maintain the canine root in alveolar bone. The -6 ° figure

coordinates well with the 5° torque changes m ade to the

specification in the lower p rem olar region. The MBT™

philosophy uses two types of lower cuspid brackets (Fig. 2.42)

to provide three torque options (-6°, 0°, +6°).

-6°torqu e 0' torque

+6

:

'

  torque

F i g .  2 . 4 2  The M BT™ ph i los ophy has th ree c an ine to r qu e

poss ib i l i t ies for the lower

  arch.

w w w . a l l i s l a m . n e t

P r o b l e m

When should the three canine opt ions be used?

There are six main factors which govern selection of canine brackets:

1. Arch form

2.  Canine prominence

3.

  The extraction decision (tip control)

4 .  Overbite

5.

  Rapid palatal expansion

6. Agenesis of upper lateral incisors, where space is to be closed.

4 4

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Arch form

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If the patient has well-developed arches, and if substantial

tooth movements are not required, then

  -7 "

  upper and -6 °

lower canine brackets are normally chosen. A more ovoid or

tapered arch form may suggest the use of 0° torque brackets

for upper and lower canines. If the patient clearly has a

narrow tapered arch form (Case AL, p. 86), then +7" upper

and +6" lower brackets will be beneficial in many cases

(Figs 2.43 & 2.4 4).

Upper

1 /—"--J

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-7

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  t o r que

0"   t o r que

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a r ch f o r m

' 1

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O vo id o r t aper ed

arch form

Tapered

ar ch f o r m

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- 6 ' t o r q u e

0" t o r que

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ar ch f o r m

Taper ed

ar ch f o r m

Figs 2.43 and 2 .44 Arch for m is an imp or ta nt fac tor in se lec t ion of canine brackets in upper and low er arches .

45

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>

Canine prominence

The -7° upper and -6° lower torque canine brackets are

Overbite

In Class II/2 cases and other de ep bite situa tions there is often

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normally not correct if the patient has prominent canines, or

canine gingival recession, at the start of treatment. Brackets

with 0° torque or +7" upper and +6" lower torque should be

selected (Fig. 2.45).

a requirement to move the lower canine crowns labially, but

to maintain the roots centered in the bone. This is more easily

achieved if 0° or +6° lower canine brackets are selected (Fig.

2.46).

0" torque or

+6°

 torque

F i g .

  2 .45

  A case w i th p rom ine nt can ine roots a t the s tar t o f

t rea tmen t , w he re can ine re t rac t ion w as requ i red . A cco rd ing ly ,

zero to rque upper and lower can ine brackets are in p lace to

assist tre atm en t me chanics.

F i g .

  2 . 4 6

  I f lowe r can ine brackets w i t h 0° or +6° o f to rq ue a re

us ed ,  th is fac i l i ta tes mov ing the can ine crowns lab ia l ly wh i le

ma in t a in ing th e roots centered in the bone. This is he lp fu l in

manag ing deep b i te s i tua t ions in some cases.

The extraction decision (tip control)

Many clinicians believe that the -7° upper and -6" lower

torque canine brackets are not ideal for prem olar extraction

cases,

 or in cases where there is considerable canine tip to b e

corrected during treatment. They prefer brackets with 0°

torque for use with canine retraction mechanics and in any

case where it is necessary to substantially change canine tip.

The thinking behind this view is that the 0° brackets tend to

maintain the canine roots in cancellous bone, thereby making

tip control of the canine roots easier. The 0" canine bracket

carries a hook, as it is often considered for cases which require

canine retraction (Fig. 2.45) or Class II mechanics.

Rapid palatal expansion cases

After rapid palatal expansion, widening of the upper arch

creates a secondary wide ning in the lower arch. There are

torque changes (uprighting) among the lower teeth

5

  and 0°

or +6° lower canine brackets are recommended to assist this

favorable change.

4 6

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Agenesis of upper lateral incisors,

where sp ace is to be closed

N

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>

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If one or both upper lateral incisors are missing, a decision

may be made to close the spaces, and bring the canines

mesially into contact w ith the c entral incisors. In this

situation, it is helpful to invert the  -7 °  upper canine bracket

180°. This changes the torque to +7°, but  the tip stays the

same at 8" . The  left  side bracket is placed on the left canine

and the right side bracket is placed on the right ca nine. It is

not correct to place the left  canine  bracket on  th e  right  canine

or vice versa.

The inverted canine bracket is well adapted to the tooth

surface, and the in-out dimension will be correct. At the

rectangular wire stage, this helps to torque the canine  root

into a palatal position with a m inimum of wire bend ing

(Fig. 2.47).

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F i g .

  2 . 4 7  Th is case had agenes is of the u ppe r r igh t la te ra l

inc isor . Versa t i l i t y featu res of th e M BT™ sys tem are being used

to as si st t r e a tm en t m ec han ic s. The upper r i gh t c an ine b rac k e t is

i nv e r ted 180° . The uppe r r i g h t f i r s t pe rm ane n t m o la r c a r r ies a

low er l e f t s ec ond m o la r bonded tube w i t h z e ro r o ta t i on t o

ass is t in achiev ing a good C lass I I molar re la t ionship at the end

of t rea tme nt (F ig . 2 .58, p. 51) .

4 7

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In te r changeab le l ower i nc i so r b racke ts

>

For the lower incisor brackets, 0" tip was used to reflect the

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research findings, and to make less demand on lower arch

anchorage. An addilional benefit is that the 0" tip allows all

the lower incisor brackets to be interchangeable

(Figs 2.48 -2.50 ), thereby assisting inventory control.

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Interchangeable

F i g .

  2 . 4 8

  The 0° t i p fea tur e o f the lower inc isor b rackets a l lows them to be in te rcha nge ab le .

F i g .

  2 . 4 9

  Lower incisor brackets have zer o t ip, an d are

in te rchangeab le .

F i g .

  2 . 5 0

  In t ra -or a l rad iog raphs sho win g para l le l low er inc isor

roo ts in the case fea tu r ed in the ad jacen t pho tog rap h .

4 8

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Interchangeable upper premolar brackets

Similar comments can be m ade concern ing the upper

anchorage, and to assist in achieving a Class  I  relationship.

>

o

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premolar brackets. The bracket system was designed with 0"

lip for all the upper premolars, to make less demand on

The 0° tip allows them to be interchangeable

(Figs 2.51-2.54), which helps inventor)' control.

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F ig .  2.51

  The 0° t i p f ea tu re o f t he p rem o la r b rac k e ts a l l ow s the m to be i n te r c hang eab le b e tw e en l e f t and r i gh t s ides, and be tw e en

firs t and second premolars.

Figs 2.52   t o  2 .5 4  U pper p rem o la r b rac k e ts hav e z e ro t i p , and

are in terchangeable bot h be twe en f i rs t and second prem olars

and between the le f t and r igh t s ides . The canine ro ots are w el l

pos i t ioned, w i th cor rec t t ip .

F i g .

  2 .53

Fig. 2.52

F i g .

  2 .54

49

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>

Use o f up pe r second mo la r tube s o n

f i rs t molars in non-HG cases

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The recommended specification for upper first and second

molars is -14° torque, 0° tip, and 10° anti-rotation. The

upper second molar tube may therefore be used on the upper

first molars, for cases where headgear will not be required

(Figs 2.55 & 2.56 ).

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F i g .  2 . 55  Uppe r second molar a t tac hm ents may be used on upp er f i rs t mo lars in cases wh ere he adge ar is no t r equ i re d .

F i g .  2 . 56  Th is non-e x trac t ion case d id not requ i re head gear

suppo r t , and an uppe r second mo la r tube w as bonded on to the

upper f i rs t mo lar .

F i g .  2 . 57  The upp er second mo lar tu be may be used on up per

f i rs t mola rs fo r cases wh ere headg ear is no t nee ded .

50

www.allislam.net  

Use of low er second mo lar tube s for the

upper f irst and second molars of the

opposite s ide, w h e n f inis hin g cases in a

can be achieved by using lower second molar tubes for the

upper molars, and changing sides, left going to right, and

right to left (Figs 2.58-2.60). Also the tube is placed at a

>

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Class II molar relationship

It is often difficult to achieve good finishing and detailing in

cases which are treated to a Class II molar relatio nsh ip, after

extraction of two premolars in the upper arch only.

It helps if upper m olar tube s can b e used which will deliver

zero rotation (compared with the normal 10° rotation) and

zero tip (compared with the normal 5" tip). This versatility

different tip position, with more enamel from the mesial cusp

visible than from the distal cusp. This introduces the

necessary tip adjustment.

In some of these cases, it is correct to use no rmal upp er

molar tubes to achieve most of the treatment objectives, and

then to switch to lower second molar tubes for finishing. The

lower second molar tube s may be used from the outset in

cases where a lot of treatment mechanics will not be needed.

/ - '

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1/1

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Fig.

 2.58

  When f in ish in g cases in a C lass I I mo la r r e la t ion sh ip , i t can be he lp fu l to p lace low er second mo lar a t tac hme nts on upp er

f irs t and second molars o f th e contra la te ra l s ide du r in g the f in is h ing s tages. The low er a t tac hm ents have 0° ro ta t io n , and norm al ly in

these cases i t is appro pr ia te to encourage upper molars to ro t a te mes io -pa la ta l ly . A 0° ro t a t i on mola r a t tac hm ent is there for e

pre ferable to the normal uppe r molar a t ta chm ent , w h ich has 10° ro t a t i on .

Figs 2.59

  and

  2 .6 0

  A dec is ion was made to t re a t th is case to a Class II mo la r resu l t . Lower second mola . r tube s, wh ic hh av e zero

ro tat ion,

  a re be ing used on the contra la tera l s ide o f the upper arch on f i rs t and second molars to ass is t ia a 'ch iev inggood molar

occlusion.

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51

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N l

>

ADDITIONAL BRACKET AND TUBE

OPTIONS

Lower s ec ond p r em o la r t ubes

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Since the bracket system was released in May 1997, the

MBT™ treatment philosophy has been continually evolving

and improving, in response to clinical experience and user

input. The option of the thicker upper second premolar

bracket has been available from the outset, but other useful

options have been added since the initial release, which have

further enhanced the versatility. Some of them are reviewed

below.

Bracke t f o r sma l l upper second p remola rs

In daily practice, upper second premolars are sometimes

small. An alternative bracket, which is 0.5mm thicker than

normal, is useful for such teeth (Fig. 2.61). This bracket is

helpful in obtaining good alignment of marginal ridges in

cases with small u pper second premo lars. It requires care with

bonding, as its greater prominence makes it more vulnerable

to biting forces. Only a small inventory of u pper second

premolar brackets is required, and this should be monitored

by one staff mem ber.

Normal

bracket

0.5 m m thicker

bracket

These were developed and tested in 2000, and are likely to

find a place in the future of orthodontic treatment mechanics.

This radical development has been made possible by the

flexibility of the .016 IIANT wires, which can easily be

threaded through lower second premolar lubes at the start of

treatmen t, even if there are slight rotatio ns pre sent (Fig. 2.62 ).

F i g .  2 . 6 2  Low er second p rem o la r tubes v iew ed f ro m th e

occ lusa l. A rec tangu la r H A N T w i re has been p laced w i t ho u t

diff iculty.

Lower second premolar tubes are cleaner and more

comfortable than con ventional brackets. Their reduced bulk

causes fewer inierferences and breakages in this area, where in

the past breakages have often occurred. Normal sliding

mechanics (Figs 2.63 & 2.64) can b e achieved in a v irtually

friction-free man ner, and the lower second prem olar lub es are

self-ligating, which saves a small amount of chairside lime at

each visit.

F i g .  2 . 6 1  The th ick er bracket op t io n fo r smal l uppe r second

p remo la rs i s he lp fu l i n ach iev ing good a l ig nm en t o f ma rg ina l

r idges w i tho u t w i re bend ing .

52

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■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ M B B a a B H W a a a B a H a B H

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Fig.

  2.63  Appl iance breakages in th e lowe r second pre mo lar

regions are f requent ly encountered, even w i th carefu l bonding,

when regular brackets are used.

Lower f i rs t molar non-convert ible tubes

These have many advantages over the mo re bulky convertible

lower first molar attachments, lubes are more comfortable,

cleaner, and stronger than (he conventional convertible

brackets (Fig. 2.65). Their reduced bulk causes fewer

interferences in this important area, and this in turn makes it

easier to achieve accurate vertical bracket positioning. For

these reasons, lower first molar non-c onver tible tubes are

becoming the attachment of choice in many practices, in

preference to the more bulky convertible lower first molar

attachments.

F ig .

  2.65  Lower f i rs t molar no n-con ver t ib le tubes have many

advantages over the t rad i t ional , more bulky , conver t ib le lower

f irs t molar attachments.

F i g .  2 .64 The l ow e r s ec ond p rem o la r t ub e i s m o re c om fo r ta b le

and is norm al ly less l iab le to breakage s tha n the equ iva len t

bracket .

Lower f i rs t molar double tube and upper

f i rs t molar t r ip le tube at tachments

These were introduced for cases where segmental mecha nics

are appropriate for the case. Segmental m echanics are seldom

used by the authors, and they generally favor a gingival HG

tube.

  These attachments are useful for clinicians who

previously have used a segmental approach, and are in

transition to the MBT™ philosophy, which is based on full

arch mechanics.

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Bo n d a b l e m i n i s e c o n d m o l a r t u b e s

>

In instances where

 a

 second molar nee ds

 to be

 included,

 but

the tooth

  is

  insufficiently erupted

  for

 band placement ,

 a

 small

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tube can

 be

 bonded

 to the

  mesio-buccal area (Figs 2.66 &

2.67). These are comfortable and surprisingly effective

 for

aligning the second molar.

Figs 2.66  and 2.67  In this case, viewed from the buccal and the occlusal, tubes are in place on the lower second premolar and both

lower molars. The bondable mini second molar tubes (3M Unitek 066-504 4, 066-5033) are most useful when the lower second molar

is only partly erupted, and are surprisingly effective in clinical use.

REFERENCES

1 A n d r e w s

 L

 F 1972 The

 six

 keys

 to

  no rm a l oc c lus ion . Am er i c an J o u rna l

o f Or t ho don t i c s 62 : 296 -307

2 Sebata E 1980 An o r t h o d o n t i c s t u d y of  t e e t h and d e n t a l a r c h f o r m on

the Japanese normal occ lus ions . The Sh i k w a G ak uh o 80 (7 ) : 945 -969

3 W a t a n a b e

 K,

  Koga

 M,

 Y a t a b e

 K,

 M o t e g i

  E,

 Isshik i

 Y A

  1996

 A

m o r p h o m e t r i c s t u d y

 on

 s e t up mode l s

 of

  Japanese malocc lus ions .

 The

Sh ik w a Gak uho

4 Benne t t J , Mc Lau gh l i n R P 1 99 7 O r t h o d o n t i c m a n a g e m e n t  of the

d e n t i t i o n w i t h

 the

 p read jus t ed app l i anc e . Is is Med i c a l M ed ia , Ox f o rd

(ISBN

 1

 899066 91

 8)

  pp . 283 -288 . R epub l i s hed

  in

  2002

 by

  Mos by ,

Edinburgh ( ISBN 07234 32651)

5 Sands t rom R A, K lappe r L,  Papac ons t an t i nou S 1988 Ex pans ion of the

l ow er a rc h c onc u r ren t w i t h rap id max i l l a r y ex pans ion . Amer i c an

J ou rna l

 o f

  O r t hodon t i c s 94 : 296 -302

54

s c a n n e d

 by

 L I S T t e a m

www.allislam.net  

CHAPTER 3

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Bracket posi t ioning and case set-up

Introduction

  5 7

The need for accuracy 57

Patient man agem ent 57

Full or partial set-up? 58

Theory of bracket pos ition ing - avo iding

errors 59

Horizontal accuracy during bracket

positioning 60

Axial accu racy 61

Vertical accuracy   61

Vertical bracket positioning with gauges and

charts 62

Clinical use of gaug es 62

Recommended bracket-posi t ioning char t 63

Individualized bracket-positioning

  charts

  63

Placing m olar bands

  66

Separat ion 66

Upp er mo lar ban d placement 66

Upper molar bands - rapid maxi l lar ) ' expansion

cases 66

Lower mo lar ban d placement 67

Direct bo nd ing of brackets 68

Indirect bo nd in g of brackets 69

Advantages of indirect bo nd ing 69

Disadvantages of indirect bon din g 69

55

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INTRODUCTION

Setting up of the case is the most important aspect of the

treatment, after correct diagnosis and treatment planning.

Banding and bonding should therefore not be delegated and

P a t i e n t m a n a g e m e n t

A  calm and unhurried approach to the case set-up helps to

minimize patient apprehension and discomfort. This builds

early patient confidence, and can raise the level of

u i

03

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should be managed by the orthodontist, to ensure accuracy of

appliance placement.

The need for accuracy

Accuracy of bracket posit ion ing is essential, so tha t th e b uilt-

in features of the bracket system can be fully and efficiently

expressed. This helps treatment mechanics and improves the

consistency of the results.

cooperation later in the treatment.

1

Proper post-set-up advice should be given, as discussed in

Chapters (p. 112) .

The use of light-cured systems for bonding brackets and

cem entin g band s is helpful. These reduce time pressure on the

orthod ontist when setting up cases. The bond ing materials

should be carefully used exactly to the manufacturer's

recommendations, with correct light, to ensure good bond

strength and reduce the risk of bond failure.

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FULL OR PARTIAL SET-UP?

Enamel reduction cases

For many pa t ients , i t i s correc t to p lace a l l the brackets and

It i s normal ly necessary to carry out enamel reshaping in cases

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bands a t the s ta r t of t rea tment so tha t any discomfort i s

l imited to one episode , and a l l the tee th s ta r t to be correc ted

from the outse t . However , in some s i tua t ions , l i s ted be low, i t

may be benefic ia l to cons ider part ia l ly se t t ing up the case ,

leaving individual tee th , and in some ins tances groups of

t e e th , w i thou t a t t a c hme n t s .

Blocked-out teeth

If individual tee th a re vert ica lly or horizo nta l ly d isplac ed from

the primary arch form (Fig . 3 .1) , i t i s of ten good technique to

delay bracket ing the displaced tooth unt i l the other tee th a re

wel l a l igned, and space has been made avai lable .

Deep-bite cases

The me th ods o f s t a r ting de e p -b i t e c a s es a re s how n on

pages 134 and 135. In some cases , when i t has been dec ided

not to use a b i te p la te or occ lusa l bui ld-up, upper a rch

trea tment should be s ta r ted f i rs t . La ter , a f te r the overbi te has

started to correct, i t will be possible to place the lower incisor

brackets wi t hou t d iscomfort to the pa t ien t or risk of da m age

to the enamel or the newly placed brackets .

wi th i r i angu lar-sh aped inc isors (Fig . 3 .2 ) . It may be he lpful to

delay bracket ing the inc isors , espec ia l ly in the lower a rch. I f

lower inc isors a re bracketed a t the s ta r t of t rea tment , they wil l

i ne v i t a b ly p roc l ine a l i t t l e du r ing too th a l ignme n t , e s pe c ia l ly

in a non-e x t ra c t ion c a se . Sub s e que n t e na m e l re duc t ion ,

fol lowed b y re t ro c l ina t io n is a form of ro un d t r ipp ing. This

undes irable e ffec t can be avoided by not bracket ing lower

inc isors a t the outse t .

F ig .  3 .1 Th is ver t ica l ly and hor izonta l ly d isp laced upper r ig h t

can ine was not b racketed a t the s tar t o f t rea tment . I t was

necessary to c reate space before a t tempt ing to br ing i t in to the

line of the   arch.

F i g .  3 .2 Tr iang u lar-sh aped inc isors norm al ly requ i re reshap in g

to avo id unesthet ic b lack t r iang les . I t can be he lp fu l to de lay

p lacem ent o f b rackets in the lo wer inc isor reg ion to re duce

unw an t ed p roc l ina t ion ea r l y in t rea tme n t . T rea tme n t mechan ics

can be easier i f low er incisors of a tr i an gu lar shape are

re -shaped be fo re b racke t p lacemen t .

Sliding jig cases and mixed dentition cases

Uppe r b i c us p ids a nd s ome t ime s uppe r c a n ine s a re no rma l ly

not bracketed when s ta r t ing cases where a s l id ing j ig (Case

TC, p . 195) wi l l be used to control or d is ta l ize upper molars .

In ma ny mixe d de n t i t i on t r e a tme n t s , on ly the pe rma ne n t

tee th are inc luded in the se t -up. Primary tee th may be

inc lude d in s ome c a s e s , e i the r to improve the s t re ng th a nd

s ta b i l i t y o f the a pp l i a nc e , o r t o in f lue nc e the pos i t ion o f the

primary tee th .

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THEORY OF BRACKET POS ITIONING -

AVOIDING ERRORS

Ever\' effort shou ld be m ad e lo achiev e accur ate bra cket

with the SWA, with bracket wings para l le l to the long axis of

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pos i t ioning. Idea l pos i t ioning can resul t in cases which show

good occlusion with lit t le effort, an d will ma ke th e finishing

stages of the treatment easier. This helps efficiency in a busy

orthodo nt ic prac t ice .

With the or ig ina l edgewise appl iance , bracket p lacement

was normal ly carr ied out us ing gauges and s tandard

mil l imeter measurements from the inc isa l or occ lusa l edge of

each tooth, irrespective of tooth size. With this system,

patients with large incisors had brackets placed more incisally

than patients with small teeth, relative to the size of the teeth.

The brackets were pos i t io ned a t d iffe rent c urva ture o n the

tee th , and th is in turn led to varia t ions in the amount of

torque and in-out produced by the brackets . However ,

because archwire bending was needed in any case , th is sys tem

was acceptable wi th the edgewise appl iance .

Andre ws in t roduc e d the c onc e p t o f t he 'midd le o f the

clinical crown ', as a mor e reliable theo retical p os iti on for use

the c l in i c a l c row n .

2

  T h i s o v e r c a m e t h e s h o r t c o m i n g s o f t h e

o r ig ina l e dge wis e me thod c onc e rn ing va r i a t ions in the

a m ou n t o f to rq ue a nd i n - ou t p roduc e d by the b ra c ke ts .

How ever, as describ ed be low , it prove d diff icult to ob ta in

a c c u ra t e ve r t i c a l pos i t ion ing us ing on ly the midd le o f the

c l in ica l c rown. Many vert ica l e rrors occurred, and the authors

now a dvoc a te the us e o f ga uge s , bu t w i th ind iv idua l i z e d

bra c ke t -p os i t ion ing c ha r t s (p . 63 ) . The s e a dhe re to Andre ws '

p r inc ip le o f the midd le o f the c l in i c a l c rown bu t e ns u re

grea ter vert ica l accuracy, wi th less need for re -bracket ing.

W hen d irec t bo nd in g brackets , i t i s he lpful lo avoid

viewing tee th from the s ide , or f rom above or be low. To

prope r ly v i e w the t e e th du r ing bond ing p roc e dure s i t w i l l be

necessary for the pa t ien t to turn th e hea d, and the

o r th odo n t i s t t o c ha n ge s e a t ing pos i t ion f rom t im e to t ime

(Fig. 3.3).

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F ig .

  3 .3 When p lac ing bracke ts , i t is im po r tan t to v iew th e tee th f r om th e co r rec t pe rspec t ive .

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Horizontal accuracy during bracket

posi t ioning

Incisors and molars have relatively f iat facial and buccal

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surfaces, and small errors do not significantly affect the

posi t ion of these teeth (Fig. 3.4) . Canines and premolars have

more rounded facial sur faces , and therefore accuracy is

impor tan t because e r r or s in hor izonta l b r acke t pos i t ion ing

cause r o ta t ions . V iew ing can ines , p r e mola r s , mola r s , and

rotated incisors occlusal ly or incisal ly with a mouth mir ror

(Fig. 3.6) help s bracket po si t io nin g rela t ive to the v er t ical

long axis of the crown. Lower canine brackets should be

placed on the ver t ical midline, or s l ight ly mesial to i t , to

ensure good contact with the la teral incisors (Fig. 3.7) .

F i g .

  3 .4 Errors in ho r izo nta l b racke t pos i t ion ing cause

ro ta t ions .

F i g .  3 .5 Hor izo nta l and ver t ica l accuracy can be checked f ro m

the buccal aspect.

F i g .  3 .6 Hor iz onta l accuracy in the can ine, p rern o lar , an d mo lar

reg ions shou ld be checked w i th a mo u th m i r ro r .

F ig .  3 .7 In th is case, the low er can ine brackets we re bo nde d

s l igh t ly d is ta l to the ver t ica l mid l ine . The resu l t ing contac ts

between canines and lateral incisors are less than ideal,

especial ly on the left s ide.

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Rotated incisors

Slight mesial or distal adjustment is helpful when bracketing

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rotated incisors. On a rotated tooth, the bracket can be

bonded slightly more mesially or distally, sometimes with a

very small amount of excess composite under the mesial or

distal of the bracket base. In this way, full correction of the

rotation can be achieved with no special measures (Fig. 3.8).

F i g .

  3 .8 On a ro ta te d too th , the b racke t can be bonde d s l igh t l y

mo re mes ia l ly o r d is ta l ly . In th is way, fu l l corre c t ion o f th e

ro ta t ion can be ach ieved.

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Axia l accuracy

It is necessary to accurately visualize the vertical lo ng axis of

the clinical crown of each tooth (Fig. 3.9) to achieve accuracy,

because errors will cause incorrect tip position of teeth. The

bracket wings need to be parallel to the long axis and to

evenly straddle it. It is helpful to disregard the incisal edges of

incisors.

F i g .

  3.9 To achive axial accuracy it is necessary t o visualiz e t he

ver t ica l long ax is o f the c ro wn o f each too th .

Ver t ica l accuracy

This is the most difficult aspect (Fig. 3.10) of bracket

positioning, and accuracy is greatly improved by the use of

gauges and an individualized bracket-positioning chart

(p.

  65). This will deal with difficulties such as tooth length

discrepancies, labially and lingually displaced roots, partly

erupted teeth, and gingival hyperplasia which have been

previously reported.

3

F i g .

  3 .10 Ver t ica l accuracy is the most d i f f icu l t aspect o f

b racke t pos i t i on ing .

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VERTICAL BRACKET POSITIONING WITH

GAUGES AND CHARTS

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Clinical use of gauges

The bracket-positioning gauges are used in slightly different

ways in different areas of the mouth. In the incisor regions,

the gauge is placed at 90° to the labial surface (Figs 3.11 &

3.12). In the canine and premolar regions, the gauge is placed

parallel with (he occlusal plane (Fig. 3.13). In the molar

region, the gauge is placed parallel with the occlusal surface of

each individual molar (Fig. 3.14).

F i g .

  3 . 1 1

  In the inc isor reg io n, the gaug e is p laced a t 90° to

the lab ia l sur face.

F i g .

  3 .1 2

  In the inc isor reg ion, the gau ge is p laced a t 90° to

the lab ia l too th sur face.

F i g .

  3 .1 3

  In th e can ine and premola r reg ions, the gaug e is

p laced para l le l w i th the occ lusa l p lane.

F i g .

  3 . 1 4

  In the m olar reg ion s, the ga uge is p laced para l le l

w i t h the occ lusa l sur face o f each ind iv idua l mola r .

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B — B — ■

Recommended bracket-posi t ioning chart

In the early 1990s, because of continuing difficulties with

vertical bracket positioning, the authors investigated the

location of the center of the clinical crown.

4

  A recommended

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bracket-positioning chart was published, and is shown in

Table 3.1. It was recommended that the tooth size for the

patient be determined, by measuring either fully erupted teeth

in the m outh, or teeth on plaster models. A row could then

be chosen for the upper arch and a row for the lower arch,

and gauges used to position the brackets at the vertical heights

shown in the chosen row.

Individual ized bracket-posi t ioning charts

The recommended bracket-positioning chart can be used for

many cases. However, individualized bracket-positioning

charts are increasingly used, and are shown in figures 3.15

and 3.16. It takes little time to pro duce a hand written chart

for each patient, which can be included in the notes and

referred to at the case set-up and throughout treatment as

necessary. This is equally useful whether using direct or

indirect bonding techniques.

T a b l e 3 . 1 R e c o m m e n d e c

j r a c k e t - p o s i t i o n i n g c h a r t

7

2.0

2.0

6

4.0

3.5

5

5.0

4.5

4

5.5

5.0

3

6.0

5.5

2.0

2.0

2.5

2.0

3.5

3.0

4.0

3.5

4.5

4.0

2

5.5

5.0

4.5

4.0

3.5

1 Upper

6 .0 +1 .0 mm

5.5 + 0.5 m m

■ 5 iO;  A v e r a g e

4.5 -0 .5 m m

4.0 -1 .0 mm

3.5 3.5 4.5 5.0 5.5 5.0

3.0 3.0 4.0 4.5 5.0 4.5

2.0 2.0 3.0 3.5 4.0 3.5

2.0 2.0 2.5 3.0 3.5 3.0

1

Lower

5 .0 +1 .0 mm

4.5 + 0.5 m m

S i l l E A v e r a g e

3.5 -0 .5 m m

3.0 -1 . 0 m m

Upper

r igh t

A ve rage

for adu l ts

Lower

r igh t

2.0

2.5

3.0

2.5

4.0

3.5

4.5

4.0

5.0

4.5

4.5

4.0

5.0

4.0

5.0

4.0

4.5

4.0

5.0

4.5

4.5

4.0

4.0

3.5

3.0

2.5

2.0

2.5

I

Upper

le f t

A ve rage

for adu l ts

Low er

le f t

i

Upper

r igh t

A ve rage

for ch i ld ren

Lower

r igh t

2.0

2.0

2.5

2.0

3.5

3.0

4.0

3.5

4.5

4.0

4.0

3.5

4.5

3.5

4.5

3.5

4.0

3.5

4.5

4.0

4.0

3.5

3.5

3.0

2.5

2.0

2.0

2.0

Upper

le f t

A ve rage

fo r ch i ld ren

Low er

le f t

F i g .

  3 .15 Ind iv id ua l ize d bracke t-pos i t ion ing cha r t - be fo re com ple t ion . I t is he lp fu l to have an adu l t and a ch i ld vers ion

ava i lab le .

Upper

r igh t

A ve rage

for ch i ld ren

Lower

r igh t

2.0

2.0

2.5

2.0

3.5

3.0

4.0

3.5

S.O

4.0

4.0

3.5

5.0

-4r5~

3.5

4.5

3.5

4.0

3.5

S.O

-4T5-

4.0

4.0

3.5

3.5

3.0

2.5

2.0

2.0

2.0

U ppe r

le f t

A ve rage

for ch i ld ren

Lower

left

F i g .

  3 .16 Ind iv idua l i zed b racke t -pos i t i on ing cha r t - a f te r comp le t ion , fo r a ch i ld w i th po in te d uppe r cusp ids and a

ch ipped upper r igh t centra l inc isor .

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7.  Chart individualization for some upper

canines and lower first premolars

It is helpful in some cases to place upper can ine and lower

2. Cha rt individualization in cases with

abnorma l incisal edges

Some cases may have leeth with wear or chipping of the

incisal edges, or with crowns thai are pointed or have

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First premolar brackets 0.5 mm more gingivally, especially in

cases with pointed teeth.

developmental irregularities. The use of gauges and a standard

bracket-positioning chart will not deal with chipped or worn

leeth, or teeth of abnormal anatomy, such as pointed canines.

In som e cases, it will be easier to judge th e correct a m oun t

of incisal enamel adjustment needed after the teeth have been

aligned. In others, the patient may be reluctant to agree to

enamel adjustments at the start of treatment, and these have

to be made as treatment progresses. For such patients, it is

necessary to estimate the final shape of the incisal edge and

the length of the crowns, and am end the individualized

bracket-positioning chart accordingly.

F i g .  3 . 1 7

  T h is p a t i e n t sh o ws d i f f i cu l t b a r r e l - sh a p e d t e e t h . Th e

bracke t on the upper r igh t cen t ra l inc isor was bonded 0 .5 mm

more g ing iva l ly , in an t ic ipa t ion o f the need fo r reshap ing o f the

incisal edge.

F i g .

  3 .18

  Th is upper r ig h t la te ra l inc isor edge shou ld be

reshaped be fore t rea tment , o r e lse the b racke t shou ld be

p laced 0.5 mm mo re g in g iva l ly .

64

F i g .  3 .19

  This low er r ig ht lateral incisor edge should be

reshaped be fo re t rea tme nt , o r e lse the b racke t shou ld be

p laced 0 .5 mm mo re g ing iva l ly th an fo r the o the r incisors .

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3. Chart individualization in deep-bite

and open-bite  cases

It can be helpful to place the incisor and canine brackets

0.5 mm more occlusally in deep-bite cases. In open-bite cases,

4. Chart individualization in premolar

extraction  cases

In premolar extraction cases, the height of molar attachments

is individualized to avoid vertical steps at the extraction sites.

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they should be 0.5 mm more gingival. In first premolar extraction cases, the adjustment needs to

include the second premolar bracket positions also (Fig.

3.20), for the vertical relationships between the marginal

ridges of canines and second premolars. In second premolar

extraction cases, only the height of molar attachments is

individualized (Fig. 3.21). This will ensure good vertical

relationships between the m arginal ridges of first prem olars

and first molars.

U ppe r

r igh t

A ve rage

for ch i ld ren

Low er

r igh t

2.0

s.s

3.0

-2r5-

S.S

4.0

s.s

y*<

X

4.5

4.0

4.0

3.5

4.5

3.5

4.5

3.5

4.0

3.5

4.5

4.0

X.

> «

4.0

3rf

3.S

3.0

- ^ 5 "

7<&

s.s

2.0

-2<fl-

S.S

U ppe r

le f t

A ve rage

fo r ch i ld ren

Low er

left

1

F i g .

  3 .20 Ind iv idua l i zed b racke t -p os i t i on ing cha r t fo r a f i r s t p remo la r ex t rac t ion case.

Upper

r igh t

Average

for ch i ld ren

Low er

r igh t

3.0

2.0 - ^ r J s r 4 .0

2.0 ,2<e- . a < 3.5

s.s

4.5

4.0

4.0

3.5

4.5

3.5

4.5

3.5

4.0

3.5

4.5

4.0

3.0

4. 0  >SC   - 2 ^ 2 .0

3. 5  J>%; -*tT  2.0

S.S

Upper

le f t

A ve rage

fo r ch i ld ren

Low er

le f t

F i g .  3 . 2 1

  Ind iv id ua l ized bra cket -pos i t ion i ng char t fo r a second prem olar ex t rac t i on case.

6 5

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PLACING MOLAR BANDS

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Se p a r a t i o n

Good separation is necessary (Figs 3.22

 

3.23). It assists

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accurate band placement and makes the procedure more

comfortable for the patient. Ideally, elastic separating

modules should be in place for about a week. Less than a

week can cause sensitivity of the teeth du ring b and placeme nt.

There is a greater risk of separators falling out if they are left

in for more than a week.

It is som etim es difficult to place elastic sepa rators in the

second molar regions, and metal separators (353-020) from

TP (Fig. 3.23) can be helpful in this area. Normal gray

elastomeric modules can sometimes be used between small

premolar contact points.

U p p e r m o l a r b a n d p l a c e m e n t

The upper molar tube should straddle the buccal groove, and

this can be checked by viewing from the occlusal (Fig. 3.25).

Care is needed to prevent the distal aspect of the band from

sealing too gingivally, and band-seating pressure is therefore

applied at the mesial palatal aspect initially, and then the

distal palatal aspect. 'Ihe ban d shou ld be checked from the

buccal to ensure it is parallel with the buccal cusps (Fig. 3.24).

It is helpful if the tube is welded more to Ihe occlusal on the

band, rather than to the gingival, especially for the second

molar.

F i g .

  3 .2 2  B lue S2 separato rs (3M Uni te k 406-084) are pre fer r ed

wh en po ss ib le . Go od separa t ion is necessary for ac curate ban d

p lac em ent .

Parallel

F i g .

  3 .2 3  Me ta l separato rs (TP 353-0 20) are som et ime s usefu l

in contac t areas between molars , espec ia l ly d is ta l to upper f i rs t

molars .

66

F i g .

  3 .2 4  W hen v iew ed f r om the buc ca l , t he t ub e and band

should be para l le l w i th the buccal cusps .

U p p e r m o l a r b a n d s e l e c t i o n f o r r a p i d

max i l l a r y expans ion (RME) cases

A

  different tech niqu e is reco mm end ed for RME cases. After

good separation, bands are selected which are one size too

large. They should then be temporarily cemented in place

with small amounts of glass ionomer cement, to ensure that

they remain in an ideal position during impression taking.

After impression taking, the bands can be removed, cleaned,

and sent to the laboratoiy. Separators should then be replaced

until the RME app liance can be cem ented a few days later.

F i g .

  3 .2 5  W he n v iew e d f r om the oc clus al , t he upper m o la r

tube s hou ld s t r add le t he buc c a l g roov e .

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Lower molar band p lacement

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The lower second molar tube should straddle the buccal

groove, and (he lower first molar lube should straddle the

mesio-buccal groove (Fig. 3.26). This should be checked by

viewing from the occlusal. Care is needed wh en ban ding

larger lower first molars lo ensure that the tube is not placed

too far mesially, and also to prevent the mesial aspect of

lower molar bands from seating too gingivally (Figs 3.27 &

3.28). Lower molar bands should be checked from the buccal

to ensure they are parallel with the buccal cusps. It is an error

to allow the mesial aspect of the band lo seat too gingivally

(Fig. 3.28 ). It is helpful if the tube is welded mo re to th e

occlusal on the band (ideally at 2.0 mm or 2.5 mm), rather

than to the gingival.

Convertible tubes are more bulky than non-convertible

tubes, leading to occlusal interferences, and the tendency to

place the band too gingivally. It is therefore easier to place

lower ban ds with non-convertible lubes (Fig. 3.29).

F i g .  3 .26 The l ow er m o la r t ube s hou ld s tr add le t h e buc c a l

g roo v e . W i th l a rge l ow er f i r s t m o la r s, i t m ay be he lp fu l t o p lac e

the tube a l i t t l e d i s ta l o f t h i s pos i t i on .

Parallel

F i g .  3 .27 The m es ia l o f t he l ow er f i r s t m o la r ba nd s hou ld no t

be s ea ted to o l ow .

F i g .  3 .28 I t is an er ror to a l lo w the mes ia l o f th e lowe r m olar

bands to seat too g ing iva l ly , as happened in th is case.

F i g .  3 .29 Low er m o la r non-c o nv er t i b le t ubes a re o f t en

preferable to conver t ib le tubes , because they are less bulky .

They a re s t r onger , m ore c om fo r tab le , and c aus e few er

in te r fe renc es .

67

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DIRECT BONDING OF BRACKETS

After cleaning of the enamel surface, etching, and application

of primer, the positioning and bonding of the bracket are

carried o ut in five stages:

4.5 4.0 4.5 4.0

3.5 3.5 4.0 3.5

3.5

3.0*

2.5 2.0

2.0 2.0

U pper

le f t

A v e r a g e

fo r c h i l d ren

Low er

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1. The bracket is positioned at the estimated mid-point of the

clinical crown, with bracket wings parallel to the long axis

of the clinical crown. The bracket is then pressed three-

quarters of the way on to the tooth surface at this position

(Fig. 3.30A).

2.  Excess bonding agent is then removed (Fig. 3.3013).

3.

  Vertical position is checked with a gauge, to equal the

individualized bracket-positioning chart (Fig. 3.30C).

4.

  Rotational and horizontal positioning is re-checked, and

then the bracket is pressed fully on to the enamel surface

(Fig. 3.30D).

5.

  Any additional excess of bonding material is removed

before light-curing (Fig. 3.30E).

left

F i g .

  3 . 3 0 A  Pos i t i on ing a t t he es t im a ted m id -po in t o f t he

c l in i c a l c row n , w i t h b rac k e t w ings p a ra l l e l t o t he l o ng ax is o f

t he c row n .

F i g . 3 . 3 0 B

  Removal o f excess bo nd ing a gen t .

F ig . 3 .30C

  C hec k ing v e r t i ca l pos i t i on in g .

F i g .

  3 . 3 0 D  R e -c heck ing ax ia l and ho r i z on ta l p os i t i on in g .

68

F ig . 3 .30E

  L igh t -cur in g af ter remov al o f any ad di t i on al excess

b o n d i n g m a t e r i a l .

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INDIRECT BONDING OF BRACKETS

There is current ly renew ed in teres t in indirec t bo nd in g, o wi ng

to the improve d a dhe s ive s wh ic h ha ve be e n de ve lope d , be l t e r

t ray mater ia ls , and upgraded des ign of re t rac tors , such as the

preference to bands for pa t ients wi th a h is tory of bac ter ia l

e n d o c a r d i t i s .

7

  Indirec t bon di ng is therefore useful for th is

s ma l l g roup o f pa t i e n t s , who ne e d to ma in ta in a ve ry h igh

7

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Nola™ re trac tors used in the Kola™ Dry Fie ld sys tem. This

upsurge in in teres t i s par t ly dr iven by the acceptance within

the o r th odo n t i c s pe c ia l ty tha t a c c u ra c y o f b ra c ke t pos i l io n ing

is v i ta l to success in mo der n or tho do nt ic s , and tha t indirec t

bo nd ing tec hniq ues , i f careful ly used, can prov ide grea ter

accuracy.

In 199 9, So ndh i rep orted o n a new res in , spec if ica lly

de s igne d fo r ind i re c t bond ing .

5

  H e r e c o m m e n d e d m a k i n g a

l ight-cured adhes ive base for each bracket and then indirec t

bon d ing w i th the ne w c he mic a l -c u re d ma te r i a l . The v i s c os ity

of the Sondhi mater ia l was improved by the use of 5% fine

particle fumed silica filler, which also helped to fill any small

d i s c re pa nc ie s be twe e n e na me l a nd the c us tom ba s e , a nd

curing was comple te in 2 minutes . This mater ia l has seen

wide s p re a d a c c e p ta nc e .

C ur re n t ly , ma ny improve me n t s a re be ing in t roduc e d a nd

evalua ted a nd it is bey on d the sco pe of th is boo k to give ful l

de ta il s a nd re c om me nda t ion s c onc e rn ing ind i re c t bon d in g

techn ique . Th e reader is re ferred to the pu bl ic a t io ns by

Sondh i ' a nd a l s o the t e c hn ique a dvoc a te d by Ka la nge ' ' u s ing

the So ndh i m ater ia l , as wel l as the manu fac tu rer 's l i te ra ture .

ADVANTAGES OF INDIRECT BONDING

Indirec t bonding is more accura te , espec ia l ly in the molar

regions , and has the advantage tha t no separa t ion

a pp o in tm e n t i s ne e de d . Th e t e c hn iq ue re duc e s the a m ou n t o f

chairs ide t ime for the or thodont is t , and a lso the pa t ient has a

s ho r t e r a ppo in tme n t fo r the c a s e s e t -up .

I t may b e preferable to band the upp er m olar s if a

headgear is to be used, because pos ter ior bands are s t ronger

tha n bonds . O the rwis e the re a re no ba nds on the pos te r io r

tee th , which ass is ts in ora l hygiene control . I t has been

re c omme nde d tha t b ra c ke t s s hou ld a lwa vs be us e d in

leve l of p laque control , and who should r inse twice da i ly

wi th c h lo rhe x id ine 0 .2% mou thwa s h fo r 2 da ys p r io r to the

s e t - u p a p p o i n t m e n t , a n d a l s o p r i o r t o s u b s e q u e n t a d j u s t m e n t

visits .

DISADVANTAGES OF INDIRECT BONDING

An extra se t of impre ss ion s is nee ded for indirec t bo nd in g

c a s es , a nd the p roc e du re i s t e c hn ique s e ns i t ive . A l th ough

bo nd ing a nd t ra y c ons t ru c t ion t e c hn ique s a re c on t inu ing to

be ref ine d, t hos e us ing ind i re c t bon d in g c onf i rm tha t t he

technique needs to be as perfec t as poss ible , and tha t i t i s an

a dva n ta ge i f t he re i s a t e c hn ic i a n w i th s u i t a b le l a bo ra to ry

facilities in the practice.

C ons ide ra b le l a bo ra to ry t im e i s r e qu i re d . Aft er t he mode l

ha s be e n poure d , t he o r th odo n t i s t d r a ws a pe nc i l l i ne on the

cro wn of each too th to represen i the long axis . The techn ic ian

wil l then be able to p lace Ihe brackels onto the model in

a pprox ima te ly the c o r re c t pos i t ion , a nd s to re i t i n a da rk box .

The o r thodon t i s t w i l l s ubs e que n t ly pos i t ion the b ra c ke t s

idea l ly , a t a con ven ien t t ime. I he auth or s f ind tha t pre-c oated

(APC™) brackets a re mos t e ff ic ient for labora tory use , as they

a re c onve n ie n t , c l e a r ly ide n t i f i e d ( s o tha t mix -ups do no t

oc c u r ) , a nd f re e f rom c on ta mina t ion . Ihe t e c hn ic i a n c a n the n

proc e e d w i th t r a y c ons t ru c t ion a n d the o the r l a bo ra to ry

p roc e dure s . A t the t ime o f bond ing , i l i s impor t a n t t o in fo rm

the pa t ient tha t the brackei pos i l ioning was carr ied out by the

o r t h o d o n t i s t .

Al th oug h th ere a re d isad van tages , it is l ike ly tha t indirec t

bo nd in g wil l see grea ter use than in the pas t . Th is is du e to

the need for grea ter accuracy in bracket pos i t ioning and

be c a us e o f the improve d t e c hn ique s a nd ma te r i a l s wh ic h a re

current ly ava i lable .

REFERENCES

1 Gros s A M 1990 I nc reas ing c omp l i anc e w i t h o r t h od on t i c t r e a t m en t .

Chi ld and Fami ly Behav ioura l Therapy 12(2)

2 A nd rew s L F 1989 S t ra igh t -W i re - t he c onc e p t and t he a pp l i anc e .

Wel ls Co, LA

3 Benne t t J , Mc L augh l i n R P 1997 Or t hod on t i c m ana gem en t o f t he

den t i t i o n w i t h t he p read jus t ed app l i anc e . Is is Med i c a l Med ia , Ox f o rd

( ISBN 1 899066 91 8) pp . 28- 40 . Republ ished in 2002 by Mo sby ,

Edinburgh ( ISBN 07234 32651)

4 Mc La ugh l i n R P, Benne t t J C 1995 B rac k e t p l ac em en t w i t h t he

p read jus t ed app l i anc e . J ou rna l o f C li n i c a l O r t h odon t i c s 2 9 : 302 -311

5 Sondh i A 1999 E f f i c i en t and e f f ec t i v e i nd i rec t bon d in g . Ame r i c an

J ou rna l o f O r t hodo n t i c s and D en t o f ac ia l O r t hoped i c s 115 : 352 -359

6 Ka lange J T 1999 I dea l app l i anc e p lac em en t w i t h APC b rac k e t s and

ind i rec t bo nd i ng . J ou rna l o f "C l in i c al O r t hodon t i c s 33 : 516 -526

7 Rober ts G J , Lucas V S, Om ar J 2000 Bac t er ia l endo card i t is a nd

o r t ho don t i c s . J ou rna l o f t h e R oy a l C o l l ege o f Su rgeons , E d inbu rg h

45 : 141 -145

69

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Problem

CHAPTER

i a a  a « « n ' n i — a — — » u i u r i n r m y  I I I .MII r u n n u M I M M i M M « w t a a » ai » « » » «» a » M M »« W M P M M w a

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Arch f o rm

Introduction

  72

The search for the ideal arch form 72

Relapse tenden cy after chan ging arch form 72

Cases where expansion may be stable 72

Variation am on g hu ma n arch forms 73

Sum ma ry of the issues facing the clinician 73

Practical so lut ion s 74

The use of three arch forms 74

Recom mend ed rat ios 75

The tapered arch form 76

The squ are arch form 76

The

 ovoid arch form 76

Systemized m anagem ent o f arch form

  7 7

Standardized versus customized wires 77

The use of clear templates at the start of

treatment 77

Arch form contro l early in treat me nt 77

Arch form control with rectangular

HANT wires 78

Arch form control with rectangular steel

wires 78

Custo mizin g - dete rmi ning 1AF for each

patient 78

Modifications to arch form and archwire

coordination

  80

Posterior torqu e consid erations 80

After maxillary exp ansio n 80

Upper arch expansion with archwires 81

Upp er arch expan sion with a jockey wire 82

Asymmetries 82

Arch form during finishing and detail ing - the

nee d for settl ing 83

Arch form con sider ation s during retent ion 83

Stock control protoc ol for archwires 84

Case AL A Class I case with a tapered arch

form 86

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INTRODUCTION

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During the era of standard edgewise, most orthodontists

customized archwires to each patient 's arch form. When the

preadjusted appliance became available, there seemed to be

an unwritten assumption that one arch form was appropriate,

In 19 95, De La Cruz et al

6

  reported on long-term changes

in arch form of

 45

 Class I and 42 Class 11/1 treated cases, a

minimum of 10 years post-retention. They concluded that

arch form tended to return toward the pre-treatment shape

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33

7 2

and it could be used for all cases with the preadjusted system,

lime has shown that this assumption was not correct. Some

customizing of the arch form for individual patients is

importan t. In-o ut is built into the preadjusted appliance,

which avoids the need for first-order bends. This simplifies

arch form, but it does not eliminate the need to use different

shap es for different individu als.

In order to properly manage arch form in a modern

orthodontic practice, there needs to be a balance between

efficiency (a single arch form for all patients) and accuracy

(the custom izing needed for case stability). In this chapter, a

short literature review will be presented to support the need

for this balance, followed by the description of a practical

system for arch form management.

Th e s ea rc h f o r t h e i d e a l a rc h f o r m f o r t h e

h u m a n d e n t i t i o n

Arch form has been discussed in denial and orthodontic

publications for over a century. Many of the early attempts to

explain and classify the human denial arch form involved

geometric terminology such as ellipses, parabolas, and

catenary curves. Ideal arch forms were described by Ilawley,

1

Scott,

2

  Brader' and others. The authors have previously

reviewed this early work,

4

  some of which was for full

dentures, but feel it has little relevance to modern

orthodontics. Similarly, the search for an 'ideal' arch form,

suitable for every patient, has been an unrealistic goal because

of the wide individual variations (p. 73).

Re lapse ten de ncy a f te r chan g in g a rch

f o r m

In 1969, in a chapter on retention in Graber's text, Riedel

5

reviewed previous studies on the stability of arch form. lie

cited numerous authors who had reported that when inter-

canine and inter-molar width had been changed during

orthodontic treatment, there was a strong tendency for these

teeth to return to their pre-lreatment position. He cited only

one author who had reported the stability of a  slight increase

in mandibular inter-canine width after all retention had been

removed for what was termed an 'adequate period'. Riedel

postulated that 'arch form, particularly in the mandibular

arch, cannot be permanently altered during appliance

therapy.'

after retention and that the greater the treatment change, the

greaier the tendency for po st-retention chang e. They suggesled

that the patient 's pre-treatment arch form appeared to be the

best guide for future arch form stability, but emphasized that

minimizing treatment change was no guarantee of post-

retention stability.

In 1998, Burke el al

7

  used meta-analysis to review 26

previous studies of mandibular inter-canine width. They

concluded that 'regardless of patient diagnostic and treatment

modalities, mandibular inter-canine width tends to expand

durin g treatment by abou t 1 or 2 millimeters, and to contract

post-relention lo approximately the same dimension'.

The paper by Burke et al confirms the overall message from

the orthodontic literature, thai if arch form is changed during

orthodontic treatment, in many cases there will be a tendency

for relapse to the original dimensions. This is particularly true

of inter-canine width. Changes in inter-molar width seem to

be more stable.

Cas es w h e r e e x p a n s i o n o f l o w e r i n t e r -

c a n i n e w i d t h m a y b e s t a b l e

In most cases, the lower huer-canine width should not be

increased during treatment, because of the risk of relapse.

Felton el al

8

  pointed out that buccal uprighting will result in

lower anterior relapse in approximately 70% of cases.

I

 lowever, the 3 0% of cases in w hich buccal uprighting w ill be

stable will probably include:

Deep-bite cases (such as Class

 11/2

  cases) in

which lower canines have inclined

lingually in response to the palatal

contour of the upper canines

As the bite is opened, the lower canines can be uprighied. The

overbite corrections must remain post-treaimenl for this

movement to be stable. In 1974, Shapiro

1

' reported on

changes in arch length and inter-molar width in 22 non-

extraction cases and 58 extraction cases after treatment and

post-reienlion. He concluded that mandibular inter-canine

width showed a strong tendency to return to its pre-treatment

dimension in all groups, with the exception of Class 11/2

cases. Expansion of inter-canine width in treated Class 11/2

cases showed significantly greater stability than Class I or

Class

  11/1.

  Post-reienlion arch length reduction was also less

in the Class 11/2 group. Shapiro's interesting findings could

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possibly be due lo the fact that Class 11/2 cases normally show

a deep bite, with lower canines inclined lingually in relation

to the palatal surface of the upper canines. When the bite is

opened, the incisal edges of the lower canines may move

S u m m a r y o f t h e is su es f a c i n g t h e

c l in ic ian

r

3

c

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labially (Fig. 2.46, p. 46), but the apices of the roots of these

teeth may move lingually, with the bodies of the leeth

remaining in the same position.

Cases where rapid maxillary expansion is

indicated in the upper a rch and this

expansion is ma intained post-treatment

Ladner and Muhl

10

  have reported that the lower arch will

follow this with buccal uprighting, which can be stable. The

amount of this response was studied by Sandstrom et al,"

who observed that lower canines will upright and increase

inter-canine width by an average of 1.1 mm, and molars will

upright and increase inter-molar width on average 2.9 mm.

This effect does not seem to produce an extensive am ou nt of

additional space in the lower arch. Haas

12

  reported on

aggressive upper arch expansion, and found an increase in

inter-cuspid width of 3-4 mm in only 'a few cases'.

Despite the overwhelming evidence on the instability of

lower arch expansion, Braun et al

13,1

'

1

  reported that the most

popular nickel-titanium archwires sold by the major

orthodontic companies expand the lower inter-canine width

by 5.9 mm and the upper inter-canine width by 8.2 mm on

average.

Research papers an d clinical observations a re giving

clear messages:

• There are extensive variations am ong hu ma n arch

forms.

• As a result of these variatio ns, there does not seem

to be any single arch form that can be used for all

orthodontic cases.

• If the patie nt's original arch form is chang ed d uri ng

treatment, there is a strong tendency (in as much as

70%

  of cases) for the arch form to return to its

original shape after appliances are removed.

1

  low do the above findings affect the clinical

orthodontist? Do they mean that archwires must be

individually customized for each patient? Or can some

form of preformed archwire system be used, which will

be helpful to the orthodontist, even though some

modifications may be needed?

In the following pages a systemized approach to

arch form m anag eme nt is described and reco mm ende d.

V a r i a t i o n  a m o n g h u m a n  arch  f o r m s

Most authors have acknowledged that there is variability in

the  size and shape of human arch form. For example, in 1987

Felton et al

8

  published a study to find out whether an ideal

orthodontic arch form could be identified. They examined the

mandibular casts of 30 untreated normal cases (from

Andrews' 120 n orm als study), 30 Class I non-extraction cases,

and 30 Class II non-extraction cases. They found that no

particular arch form predominated in any of the three

samples. They stated that custom izing arch forms appeared to

be necessary in many cases to obtain optimum long-term

stability, because  of  the great variability in arch form observed

in  th e  study.

It is generally accepted that the dental arch form is initially

shaped by the form   of  the underlying bone, and then after

eruption of the teeth, the shape  becomes influenced by the

oral musculature. Genetic and environmental differences

produce great variability, which is confirmed in day-to-day

clinical observation.

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PRACTICAL SOLUTIONS

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The use of three arch forms

Arch forms were first classified as tapered, square, and ovoid

by Chuck

15

  in 1932. Numerous authors and clinicians have

Tapered 50%

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3D

used this classification over the years, and eventually

orthodontic manufacturers began producing arch forms based

on this classification (also referred lo as narrow, normal, and

broad).  Such a three arch form approach allows for greater

individualization than the single arch form approach,

especially in the early archwire stages. If one classifies the arch

forms in the Felton el al

s

  study into lapered, square, and

ovoid, the ratios of these shapes in the Andrews', Class I, and

Class II samples are approximately as shown in Table 4.1 .

In an unpublished study in one of the authors' practices,

the lower arches of 200 consecutive cases (pre dom inantly

Caucasian) were evaluated with tapered, ovoid, and square

transparent templates. The results (Fig. 4.1) were thai

approximately 50% of the lower arch forms were tapered, 8%

were square, and 42 % were ovoid. This is quite similar lo the

Felton results.

T a p e r e d ( % ) S q u a r e d ( % ) O v o i d   ( %

A n d r e w s ' c a s e s

C l a s s I s a m p l e

C las s I I s amp le

2 7

6 0

5 3

2 0

3

7

5 3

3 7

4 0

T a b l e 4 . 1

Nojima et al '

6

  used tapered, square, and ovoid templates

to evalu ate the arch forms of Class I, Class II, and Class III

cases in both (apanese and Caucasian samples (Figs 4.2 &

4.3).  The Caucasian sample showed 44% lapered arch forms,

18 %  square arch forms, and 3 8% ovoid arch forms. However,

Nojima et al included an equal proportion of Class III cases

(of which 44% have square arches) in both samples, and a

typical Caucasian caseload would contain fewer Class 111

cases.  Hence the ratios of 5 0%  tapered, 8% square, and 42%

ovoid are a more probable reflection of a  predominantly

Caucasian practice. Global differences are clearly significant,

and it is interesting thai the Japanese sample showed ratios of

12%

  tapered, 46% square, and 42% ovoid. This shows the

opposite ratio of square to tapered arch forms, compared with

the Caucasian sample.

Ov o id 42%

| | Square 8%

Pract ice sa mple

F i g .  4 . 1

E

Tapered 12%

Ov o id 42%

Square 46 %

Nojima rat ios

(Japanese pa t ients)

F i g .

  4 . 2

| | Tape red 44 %

| | O void 38%

| | Square 18%

1

Nojima rat ios

(Caucasian patients)

7 4

F i g .  4 . 3

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R e c o m m e n d e d r a t i o s

li has been noted (p. 72) that two categories of cases do show

post-treatment stability after minor lower arch buccal

r

Tapered 45%

c

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uprighting. These are palatal expansion cases and deep-bile

cases.

  Thus the recommended ratios (Fig. 4.4) of 45%

tapered, 10% square, and 45 % ovoid (p. 84) seem practical

for a predominantly Caucasian practice.

The three shapes - tapered, square, and ovoid - used by

the authors early in t reatment are show n below (Figs 4.5- 7).

Later in treatment an individual arch form (1AF) is used for

each patient (p. 78).

F i g .  4 .4

Fig.  4 .5 T ape red F ig . 4 .6 S qua re F ig . 4 .7 Ovo id

71

| | Ovoid 45%

Square 10%

<

Recommended ratios

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The tapered arch f or m

This arch form has the narrowest inter-canine width and is

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useful early in treatment for patients with narrow, tapered

arch forms (Case AL, p. 86). It is particularly important to use

this form for patients with narrow arch forms, and especially

in cases with gingival recession in the canine and premolar

regions (mo st frequently seen in adult cases). The tape red

arch form is often used in com binatio n with inverted canine

brackets for these patients.

Cases undergoing single arch treatment often require the

use of the tapered arch form. In this way, no expansion of the

treated arch occurs, relative to the untreated arch. The

posterior part of this arch form can easily be modified to

match the inter-molar width of the patient.

The square arch form

This arch form is indicated from the start of treatment in cases

with broad arch forms (Case CW, p. 152). It is also helpful, at

least in the first part of treatment, for cases that require buccal

uprighting of the lower posterior segments and expansion of

the upper arch. After overexpansion has been achieved, it may

be beneficial to change to the ovoid arch form in the later

stages of treatment. The square arch form is useful to

maintain expansion in upper arches after rapid maxillary

expansion (p. 80).

The ovoid arch form

Over the past 15 years, this has been the a utho rs' preferred

arch form for most of their cases,

17

  for example, Case |N,

p.

  120. The combined use of this arch form with appropriate

finishing, settling, and retention procedures (p. 289) has

resulted in a majority of cases with good stability, and

minimal amounts of post-treatment relapse. However, the

recent research (above) indicates that a greater number of

tapered arch forms should also be used. When superimposed,

the three shapes vary mainly in inter-canine and inler-first-

premolar width, giving a range of approximately 6 mm (Figs

4.8 & 9) in this area.

7 6

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SYSTEMIZED MANAGEMENT OF ARCH

FORM

Standardized versus customized wires

It is not practical to customize every wire for every patient in a

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modern orthodontic practice, and it is not necessary if the

system described below is used.

Multistrand .015 or round HANT .016 wires are used early

in treatment as the initial leveling and aligning archwires, a nd

these exert light forces. Their form is often temp orarily

distorted, due to tying into malaligned teeth. They can be

expected to have little influence on arch form for the short

periods that they are used. It is therefore reasonable to use a

standard ovoid arch form for these early wires.

As the teeth align, and the treatment progresses into

heavier 11ANT and then steel wires, archwires gradually have

more effect o n arch form. This is because of their greater

tensile strength and the fact that they are used for a longer

period of time. It is therefore beneficial, later in treatment, to

customize wires to an arch form suitable for each individual

patient.

The use of c lear templates at the start of

t rea tment

Clear templates can be used to assess the patient's lower

model at the start of treatment, to determine whether the

lower arch has a tapered, square, o r ovoid form (Fig. 4.10).

Often there will only be an approximate fit at this stage, but it

is useful to have an early indication.

TAPERED SQUARE OVOID

F i g .

  4 .1 0 C lear tem pla tes may be used at the s tar t o f t re atm en t to assess wh eth er th e pat ie nt ' s low er arch has a tap ere d, square or

ov o id f o rm .

7 7

F i g .  4 .8 U pper a rc h f o rm

s uper im pos i t i ons .

F ig 4 .9 Low er a r c h f o rm

s u p e r i m p o s i t i o n .

Arch form contro l ear ly in t reatment

It is recommended that all round wires be stocked in ovoid

form only (p. 84). this helps to limit inventory. The opening

wires will normally be .015 or ,0175 multistrand, .016 HANT,

or sometim es .014 steel. These m ay all be used in ovoid form,

with no customizing.

As leveling and aligning progress into heavier ro und wires

(pp 111 & 112), there will be a need to customize some

wires.

  Consequently, the ovoid .016, .018, and .020 round

steel wires should be adapted as necessary for individuals

with a tapered or square form at the start of treatment, as

previously determined using the clear templates. Archwire

adaptation will obviously not be needed at this stage for

individuals with an ovoid starting arch form.

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** A r c h f o r m c o n t r o l w i t h r e c ta n g u l a r H AN T

w i r e s

>

^ The ma n ufa c iu re d s ha pe o f r e c t a ngu la r I IANT wi re s c a nno t be

-n cus tom ized . I t i s therefore necessary to s tock the m in taper ed,

55 squa re , and ovo id form, becau se ( l ike the heavier rou nd

wires ) they sh ou ld be used in the appro xim ate form for the

C u s to m i z i n g s t e e l r e c ta n g u l a r w i r e s -

d e te r m i n i n g t h e IAF f o r e a c h p a t i e n t

After the rec tangular  I  IANT wires hav e served the ir pu rpo se , a

.019 / .025 s t a in l e s s s t ee l a rc hwi re c an be ind iv idu a l i z e d fo r

e a c h pa t i e n t , ba s e d on the fo rm o f the lowe r de n t i t i on . An

upp e r fo rm c a n the n be ma d e wh ic h i s c oo rd ina te d w i th the

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pa t i e n t , a s de te rmine d us ing the c l e a r t e mpla te s .

Rectangular HANT wires may be in p lace for severa l

mon ths , a nd the y do in f lue nc e the pa t i e n t ' s a rc h fo rm,

especia l ly in the important canine region. I f not used in the

a ppropr i a t e t a pe re d , s qua re , o r ovo id s ha pe , t he y c a n c a us e

unde s i ra b le c ha nge s in the pa t i e n t ' s s t a r t ing a rc h fo rm.

Ar c h f o r m c o n t r o l w i t h r e c ta n g u l a r s t e e l

w i r e s

Rectangular s tee l .019/ .025 working wires have a major

inf luence on arch form. They therefore n eed to be cus tom ized

to each pa t ient 's individual a rch form (IAF). I t i s

s t ra ightforward and quick to adapt working wires lo the IAF,

and sh ap ing can be de legated an d then f ina l ly checked by th e

o r thodon t i s t . C onc e rn ing s toc k c on t ro l o f .019 / .025 s t e e l

wires (p . 84) , there a re three poss ibi l i t ies :

1 . To s tock ovoid shape only , and modify as necessary .

2 .  To s tock ovoid and tapered shapes , which wil l reduce the

a m ou n t o f w i re mod i f i c a t ion n e e de d . Th i s i s a good op t i on

i f t he c a s e loa d inc lude s m a in ly c h i ld re n , whe r e the s qu a re

arch form is se ldo m used.

3 .  To s toc k ovo id , s qua re , a nd t a pe re d s ha pe s , a nd thus

mi n im iz e the a m ou n t o f w i re a da p ta t ion ne e de d , wh i l e

accep t ing higher invento ry leve ls. W he n s tockin g a l l thre e

s ha pe s , t he re w i l l a lwa ys be a ne e d to c us tomiz e s ome

wires , becaus e the IAF for man y pa t ient s wi ll no t exac t ly

ma tc h the s ha pe o f the ma nufa c tu re d w i re s in the ba s i c

t a pe re d , s qua re , o r ovo id fo rms .

78

l owe r , a nd 3 m m w ide r in a ll a re a s . Th e fo l lowing p roc e dure

(Fig . 4 .11 A-F) is used:

• After the rec tangular HAN T s tage (Fig . 4 .11

 A) ,

  a wax

templa te is molded over the lower a rch to record the

indenta t ions of the brackets (Fig . 4 .1 IB).

• Th e .01 9/ . 02 5 s ta inless s tee l a rchw ire is ben t to the

inde n ta t io ns in the wa x b i t e (F ig. 4 .1 ID ) .

• The w i re i s t he n c om pa re d w i th the s t a r t ing lowe r m ode l ,

or a Xerox copy of the model , to ensure tha t i t c lose ly

re s e mble s the ove ra l l s t a r t ing s ha pe .

• The wire is then checke d for sym me try on a temp la te .

• Fina l ly , a Xerox copy of the wire is m ad e and s tored in the

pat i ent n otes . Thi s is the pa t ien t 's IAF. Ix w er rec tan gular

s tee l wires a re then used in the IAF sh ap e and up per s in a

fo rm whic h i s 3 m m wide r . Arc hwi re c oo rd in a t ion i s

impor t a n t t h roughou t t r e a tme n t , e s pe c ia l ly w i th the

he a v ie r round w i re s a nd t he .019 / .02 5 re c t a ngu la r s t a in l e ss

s t ee l w i re s . Th e uppe r w i re s ho u ld s up e r im pos e

a ppro x im a te ly 3 mm ou t s id e o f the lowe r w i re . Th i s i s

representa t ive of the overlap of the upper tee th re la t ive to

the lower tee th , and provides for correc t a rchwire

coordina t ion in the majori ty of cases (Fig . 4 .1 IF) .

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Fig.

 4.11 A The l ow er r ec tang u la r H AN T w i re has been

removed.

F i g .

  4 . 1 1 B  A w ax tem p la te i s s o f t ene d i n w a rm w a te r and

m o lded ov e r t he l ow er a r c h t o r ec o rd i nden ta t i ons o f t he

brackets .

F ig . 4 . 1 1 C

  T h e w a x t e m p l a t e v i e w e d f r o m t h e l a b i a l.

F i g .

  4 . 1 1 D  The .019 / .025 rec tangu la r s tee l w i r e i s be n t t o t he

inden ta t i ons .

Fig.

 4 .1 1 E  The stee l rec tan gula r w i re is checke d for sy mm etry

on a t em p la te , and th en a Xerox c opy can be m ade and us ed as

the pat ient ' s IAF for th e low er

  arch.

F i g .  4 .1 1 F

  A f t e r t he pa t i e r r t' s IAF has been de te rm in ed fo r t he

low er a r c hw i re , an upper w i r e c an be c rea ted w h ic h s hou ld

s uper im pos e approx im a te l y 3 m m ou ts ide o f t he l ow er w i r e .

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MODIFICATIONS TO ARCH FORM AN D

ARCHWIRE COORDINATION

There are som e cases that will require arch form mo dification

from the norm al IAF and the usual uppe r/low er archw ire

coordination.

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Modi f icat ion due to poster ior torque

considerat ions

The additional buccal root torque in the upper molar brackets

tends to narrow the upper arch, and the progressive buccal

crown torque in the lower posterior brackets tends to upright

the lower molar teeth and widen the lower arch (Fig. 4.12).

The combined effect of these appliance features can be a

tendency towards molar crossbite in some cases. When this is

observed, the posterior segment of the upper archwire can be

widened to 5 mm wider than the lower archwire in the molar

regions.

Modi f icat ion a f ter maxi l la ry expansion

After the uppe r arch has been expan ded with a rapid maxillary

expander or a qu adhelix (Fig. 4.I3A), two things can occur.

First, the lower arch tends to upright buccally, and second, the

upper arch tends to relapse (Fig. 4.1315). To manage these

effects, the lower arch can be widened by using a wider arch

form (usually one size wider - for example from tapered to

ovoid) and the upper arch expansion can be held with a

correspondingly wider arch form.

'1 /

Before torque correction

During torque correction

F i g .  4 .12 D ur ing c o r rec t i on o f m o la r t o rqu e , t he re is a

tend ency for a buccal c rossbite to d eve lop. I f th is is observed, i t

is necessary to w iden the pos ter ior segment of the upper

a rc hw i re .

A

\

F i g .  4 .13 Af t er u pper arch expans ion (A) , i t is o f t en necessary to w ide n the up per arch fo rm an d nar r ow th e low er arch fo rm (B) to

c oun te rac t unw an ted m o la r c hanges .

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Upper arch expansion with archwires

In some cases, arch form coordination requires special

attention, due to one arch (usually the upper arch) being

slightly smaller than the other arch. The rectangular .019/.025

steel wires can be used to help correct this condition and

There is a correct technique for archwire expansion. If the

wire is bent to expand its width (Fig. 4.14), it is important to

ma ke sure it is not overexpanded and thu s distorted from the

arch form. When the ends of the expanded wire are held, and

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achieve some arch expansion (p. 108), or to maintain

expansion previously obtained by use of a quadhelix or by

rapid maxillary expansion. This may be done by expanding

the IAF arch form in the m olar regions, or by use of th e

square arch form for a limited period.

pres.sed back towards the chosen arch form (IAF), the wire

should match that sha pe (Fig, 4.15). If overexpande d or

incorrectly expanded (Figs 4.16 & 4.17), it will not ma tch the

chosen arch form (IAF) when the ends are pressed towards it,

and this will cause problems due to narrowing or widening of

the inter-canine width.

73

Fig .  4 .14  I t  is im po r ta nt to use a cor rec t tech niq ue fo r archw ire

expansion.

F i g .  4 . 1 5  A f t er cor rec t expa ns ion, i f the ends of the arch wire

are pressed tow ard s the ideal

  a rch ,

  t he ex panded a r c h  w i l l  s h o w

c or rec t f o rm .

F i g . 4 . 1 6  Incor rec t expa ns ion.

F i g .  4 . 1 7  Incor rec t expan s ion.

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Upper arch expans ion wi th a jockey wire

There are limits to the expansion force which can be delivered

by one .019/.025 rectangular wire during routine treatment. If

necessary, particularly near the end of treatment, a little more

expansion force can be achieved by using a 'jockey arch' (Case

MS,

 pp 238 & 239). This is merely a second archwire, also

expanded, tied in place over the n ormal archwire (Fig. 4.18).

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The jockey arch m ay be of .019/.02 5 rectangular steel, or of

heavier round steel wire. If the upper first molars carry

headgear tubes, it can be conven ient to end the jockey

archwire in those tubes.

It is helpful if the normal .019/.025 wire has buccal root

torque in the molar region (Fig. 5.30, p. 108) to attempt

bodily movement of molars and avoid tipping. It is important

to have adequate bone width to achieve upper molar

expansion (Fig. 10.15, p. 290).

F i g .

  4 . 1 8  Occ lusal v iew o f a ' jockey a rch ' in p lace. This may be

o f . 019/ .025 rec tan gu la r s tee l w i r e o r o f hea v ie r r ou nd s tee l

w i r e .

Asymmetr ies

In cases where it is clear that the patient has an arch

asymmetry, and there are many such cases, the archwires later

in the treatment may be modified to assist correction of the

asymmetry (Figs 4.19-21).

F i g .  4 . 1 9

  Occ lusal v ie w of an asym metr ica l low er   arch.

Ovoid arch form

Ovoid arch form

Shape of m odified

arch wire

82

F i g .  4 . 2 0

  As y m m et r y o f t he l ow er a r c h in F igu re 4 .19 ,

c om pared w i th t he ov o id l ow er a r c h f o rm .

F i g .  4 . 2 1

  M o d i f i c a t i o n o f t he l ow er a r c hw i re t o c oun te rac t and

cor rec t the denta l asymmetry in F igure 4.19.

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ARCH FORM DURING FINISHING AND

DETAILING - THE NEED FOR SETTLING

There are importan t arch form considerations during the

closing stages of any treatm ent. A careful protoc ol allows th e

arch form to settle in the later stages of treatment.

 A

 settling

phase is required in almost every case. The following steps are

In Class II treatments (where overjel relapse may occur

during settling), a full .014 upper archwire is necessary,

bent back behind the molars (Case DO, p. 210). This may

slow the settling, but it is needed to hold the corrected

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recommended:

• Patients sho uld no t progress directly from rectang ular wires

to retainers without a phase of settling in lighter wires. The

authors prefer a full .014 stainless steel or .016 nickel-

titanium lower archwire, and an upper .014 stainless steel

sectional wire, to include only the upper incisors, in

combination with light triangular elastics, near the

completion of treatment. The patient is checked at 2-

weekly intervals for approximately 6 weeks (Case IN,

p.  124, and Case MOT, p. 274). During this period,

vertical tooth settling occurs and the upper and lower arch

forms are also allowed to settle, so that a balanc e betw een

the tongue and perioral musculature can re-establish.

• During this settling phase , teeth adjacent to extraction sites

should be lightly tied together, to prevent space opening.

• If the maxillary arch has been expan ded earlier in the

treatment, the expansion needs to be held during the

sealing phase. An upper removable acrylic plate may be

used for this (Fig. 10.22, p. 295).

overjet. Some second-order bends can be placed in this

wire to encourage proper settling.

ARCH FORM CONSIDERATIONS DURING

RETENTION

There is a constant tendency for lower incisor relapse in the

majority of cases.  Lower bonded retainers from canine to

canine (p. 307) are recommended to minimize this tendency.

In first premolar extraction cases, the bonded retainer may be

extended onto the .second premolars. Typically, a patient in

retention will have a lower bonded retainer and an upper

acrylic removab le retainer. The lower prem olars and molars

are thus free to narrow, relative to the fully retained upper

arch (Fig. 4.22). It may be necessary to modify o r leave out

the upper acrylic retainer for  2  to 4 weeks, to let the upper

premolars and molars adjust to lower arch changes

(Fig. 4.23). A new acrylic retainer can then be made. If a

vacuum-formed upper retainer is used, it may be modified for

2 to 4 weeks and then re-made.

F ig .

  4 .22 D ur ing re ten t i on , t he uppe r t ee th a re

  h e l d ,

  bu t l ow e r

molars and premolars can move lab io- l ingual ly .

F i g .

  4 .23 The upper acr y li c r e ta ine r m ay be om i t t e d o r

m od i f i ed f o r 2 t o 4 w eek s to l e t upper m o la r s and p rem o la r s

ad jus t t o l ow er c hanges . A ne w uppe r r em ov ab le r e ta ine r c an

then be m ade and f i t t ed .

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STOCK CONTROL PROTOCOL FOR

ARCHWIRES

An example of

 a

  suitable stock system is shown below. It is

possible to stock steel working wires in one, two, or three

shapes, dep endin g on the size of the practice and the desire to

minimize wire modification.

Cu stom ization of arch wires reduces the risk of relapse and

example, there will be a risk of relapse and an unna tural look

to the smile. It is therefore desirable for the clinical

orthodontist to have a system of customizing the arch form

for each patient, but without having to overstock practice

inventor)' or spend time with needless wire bending . This

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helps to achieve good esthetics. If a broad arch form is used

for an individual with a narrow facial appearance, for

chapter has described a system which the authors use and

recommend with confidence.

r~

.015 multistrand

.0175 multistrand

.014 round stainless steel

.016 round stainless steel

.018 round stainless steel

.020 round stainless steel

.016HANT

V

/^~

r

.019/ .025HANT

v

  *

s

r

  r

.019/.025 stainless steel

with soldered hooks

v_

V ^

A

Stocked in ovoid shape only

and modified to templates

as necessary

V ^

  y

_J

- .

~ ^

Stocked in three shapes:

— 4 5% tapered

— 10% square

— 45% ovoid

, .

_J

"-

^

Stocked in ovoid only, or in

three shapes (ovoid,

tapered and square) and

modified to the patient's

IAF from the wax template

J

8 4

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REFERENCES

1 H aw ley C A 1905 D e t e rmina t i on o f t he n o rm a l a r c h and i ts

app l i c a t i on t o o r t hodon t i a . D en t a l C os mos 47 : 541 -552

2 Scot t J H 1957 The shape of the d ent a l arches . Journal o f Den ta l

Research 36:99 6 1003

3 Brader A C 1972 Denta l arch form re la ted to in t ra-ora l forces .

Amer i c an J ou rna l o f O r t hodon t i c s 61 : 541 -561

4 McLaughl in R P, Be nne t t J C 1999 Arch fo rm cons iderat ions fo r

s tab i l i t y and es thet ics . Rev is ta Espana Or todont ica 29(2) :46-63

11 Sands t rom R A, K lapp er L , Pap aco ns ta nt inou S 1988 Expans ion of th e

low er a rc h c onc u r ren t w i t h ra p id max i l l a r y ex pans ion . Amer i c an

J ou rna l o f O r t ho don t i c s 94 : 296 -302

12 H aas A J 1980 Long - t e rm pos t t r ea t m en t ev a lua t i on o f r ap id pa la t a l

e x p a n s i o n . A n g l e O r t h o d o n t i s t 5 0 : 1 8 9 - 21 7

13 Braun S , Hnat W P. Fender D E, Legan H L 1998 The for m of th e

h u m a n d e n t a l

  a r ch .

  A n g l e O r t h o d o n t i s t 6 8 ( 1 ): 2 9 - 36

14 Braun S, Hna t W P, Leschinksy R, Legan H L 1999 An eva lua t ion of th e

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5 R iedel R A 1969 In : Graber T M (ed) Current o r th od on t ic con cepts and

techniques . Saunders , Phi lad elph ia

6 De La Cruz A R, Sampson P, L i t t le R M, Ar tu n J , Shapi ro P A 1995

Long- t erm changes i n a rc h f o rm a f t e r o r t hod on t i c t r ea t m en t and

re t en t i on . Amer i c an J ou rna l o f O r t hodo n t i c s 107 : 518 -530

7 Burke S P, S i lve i ra A M, Gold sm i th L J , Yancey J M, Van Stew ar t A,

Scarfe WC 1998 A meta-analys is o f ma ndib ular in terc anine w id th in

t rea t men t and pos t r e t en t i on . Ang le Or t hodon t i s t 68 (1 ) : 53 -60

8 Felton M J, Sinclair P M, Jones D L, Alexa nde r R G 1987 A

comp uter ized analys is o f the shape an d s tab i l i t y o f mand ibula r arc h

f o r m .

  Amer i c an J ou rna l o f O r t hodon t i c s 92 : 478 -483

9 Shap i ro P A 1974 Ma nd ibu la r a r c h f o rm and d ime ns ion . Am er i c an

J ou rna l o f O r t hodo n t i c s 66 : 58 -70

10 Ladner  P  T, Muh l Z F 1995 C hanges c onc u r ren t w i t h o r t h odo n t i c

t rea t men t w h en max i l l a r y ex pans ion i s a p r imary  g o a l .  A m e r i c a n

J ou rna l o f O r t hod on t i c s and D e n t o f ac ia l O r t hoped i c s 108 : 184 -193

s hape o f s ome popu la r n i c k e l t i t an ium a l l oy p re f o rm ed a rc h w i res .

Amer i c an J ou rna l o f O r t hodon t i c s and D en t o f ac ia l O r t hoped i c s

116:1-12

15 C huc k G C 1934 I dea l a r c h f o rm . An g le Or t hod on t i s t 4 : 312 -327

16 Noj ima K, McLa ugh l in R P, I ssh ik i Y, S inc la i r P M 2001 A c om para t ive

s t udy on C auc as ian and J apanes e man d ibu la r c l i n i c a l a rc h f o rm s .

A n g l e O r t h o d o n t i s t 7 1 : 1 9 5 -2 0 0

17 Ben ne t t J . Mc L augh l i n R P 1993 Or t h odo n t i c t r e a t m en t mec han i c s

and t he p read jus t ed app l i anc e . Mos by -W o l f e , London ( I SBN 0 7235

1906X)

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The following case shows  an example of a patient with a

tapered arch form and prominent canine roots at the start

of treatment.

This 15.5-year-old female patient was Class I  skeletally, with a

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high-angle vertical pattern. From the frontal aspect, she had a

narrow facial appearance, with some mandibular asymmetry

to the left. Lower incisors were retrodined at 78° to the

mandibular plane to the mandibular plane and at APo

- lm m . The facial profile was pleasing and h arm oniou s.

Dentally, the patient was Class

 1

  in the buccal segments. The

centric occlusion and centric relation were coincident,  with  no

displacemen ts at termina l closure. There was m ild crowding

of the upper and lower incisor regions, and notable

prominence of the canine roots. Upper and lower midlines

were coincident. There was a small amou nt of enamel dama ge

to the incisal edge of the upper right central incisor.

The facial appearance was reflected in the arch form, which

was narrow and tapered. There were extensive, but not deep,

restorations in first and second molars. There was a lack of

space for the third molars, with impactions on the left side,

and a supplemental upper left third molar. It was decided to

extract all the third m olars. The mild crowding would be

resolved by torqueing and uprighting of the buccal segments

and slight proclination in (he lower incisor region. The

selected arch form would be tapered, which would maintain

the basic form of the patient's dental arches.

Standard .022 metal brackets were placed. The upper and

lower canine brackets were inverted, to m aintain th e can ine

roots in bone. All the teeth, including second molars, were

banded or bracketed. The ope ning w ires were .016 HANT to

an ovoid arch form.

- ■

F i g .  4 . 2 7

F i g .  4 . 3 0

86

F i g .

  4 .33

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S N A 7 7

S N B Z 7 5

A N B

A N F H

Po-N FH

W I T S

'.  2

-1

-1

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G o G n S N  4 2

F M / 3 0

M M 3 7

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«

m m

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1 t o   A -Po

1 t o

  A -Po

t o Max  P l a n e /

t o M a n d P l a n e /

4

-1

1 0 1

7 8

m m

m m

F ig .

  4 .2 8

F i g .  4 .2 9

m

F ig .

  4 .3 1

F i g .  4 .3 2

F ig .

  4 .3 4

F i g .

  4 .3 5

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Th e .016 HAN T wi re s in the ovo id fo rm we re fo l lowe d by

.01 9/ .0 25 rec tan gular I IANT wires , wi th the se lec ted tape red

a rc h fo rm. Th e .019 / .0 25 re c t a ngu la r HAN T wi re s ha d the

effec t of torqueing and upright ing the buccal segments (Fig .

4 .40) as a resul t of the reduced torque spec if ica t ion of the

a pp l i a n c e s yst e m in lowe r p re m ola r s a nd mola r s . Th i s in tu rn

p rov ide d a dd i t iona l s pa c e fo r a n te r io r a l ignme n t . The e a r l i e r

dec is ion to invert the canine brackets a l lowed good control of

the c a n ine roo t s du r ing the l e ve l ing a nd a l ign ing s t a ge s .

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Th e .019 / .0 25 re c t a ngu la r HANT wi re s we re fo l lowe d by

.019/ .025 rec tangular s ta inless s tee l wires , wi th tapered arch

form, and with soldered hooks . The pa t ient wore l ight Class II

e las t ics for a short per iod, to reduce a smal l overje t which had

de ve lope d . The .019 / .025 re c t a ngu la r s t a in l e s s s t e e l w i re s we re

ma in ta ine d du r ing the midd le a nd l a t er pa r t o f t he t r e a tm e n t .

I t was fe l t tha t the pa t ient 's a rches had become a l i t t le too

ovo id du r ing the a l ignme n t s t a ge , a nd the .019 / .025 s t a in l e s s

s tee l wires were careful ly mainta ined in the tapered form, lo

narr ow th e arches s l ight ly . Th e occ lusa l v iews a t the end of

t re a tme n t s how tha t t h i s wa s a c h ie ve d .

Late in the t rea tment , the re ferr ing dent is t reques ted enamel

reshaping of the inc isa l edge of the upper r ight centra l inc isor .

Th i s wa s fo l lowe d by re pos i t ion ing o f the inc i s o r b ra c ke t , a nd

then re- leve l ing and a l igning us ing a .014 s tee l wire . In the

lower a rch, a .016

  I

  IANT wi re wa s us e d to c omme nc e s e t t l i ng

of the case.

F i g .

  4 .39

F i g .

  4 .42

F i g .

  4 .45

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F i g .

  4 .3 7

F i g .

  4 .3 8

-10°

-20°

-17°

-12°

-6

F ig .

  4 .4 0

F i g .

  4 .4 1

Fig.

  4 .46

F i g .

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Selec t ive up-and-down e las t ics were used with l ight wires

during the se t t l ing s tage . The l ight wires a l lowed se t t l ing of

the arch form.

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90

F i g .

  4 .4 8

A pleas ing dent a l resul t was achieved. The can ine crow n a nd

root pos i t ions resul t f rom the bracket spec if ica t ions used in

this case . These were +7° tor qu e and 8° t ip in the upp er , a nd

+6° torque and 3° t ip in the lower.

A lowe r bon de d re t a ine r a nd a n upp e r re mov a b le re t a ine r

were used. The tapered arch form was sui table for th is case

because i t re la tes to the pa t ient 's s ta r t ing lower a rch form and

is appropria te for her narrow fac ia l appearance . Early in the

t re a tme n t the a rc h fo rm be c a me a l i t t l e t oo ovo id , bu t t he

s tee l rec tangular wires were success ful ly used to res tore and

mainta in the tapered shape in to the f ina l resul t .

fac ia l ly , the pa t ient was s imilar to the s ta r t ing appearance ,

which was very sa t is fac tory . Denta l ly , there was a change in

a ngu la t ion o f the lowe r inc i so rs , w i th lm m of p roc l ina l ion

tow ards APo, an d th is he lp ed to resolve the lower an ter i or

c rowding .

F i g .

  4 .5 1

F i g .

  4 .5 4

F i g .

  4 .5 7

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Fig. 4.55

A N B

A N F H

Po-N FH

W I T S

G o G n S N

FM

M M

1 t o A-Po

1 t o A-Po

t o M a x P l a n e / 1 0 2

t o M a n d P l a n e / 8 5

m m

m m

m m

m m

m m

F i g .

  4 .58

F i g .

  4 .59

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CHAPTER 5

Ancho rage con tro l du r i ng to o th

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leve l ing and a l ign ing

In t rodu c t ion and def in i t ions 94

Short-term versus long-term objectives 94

Principles of anch orag e contro l 94

Treatment sequence to show leveling and

aligning 95

Recogniz ing the anch orag e needs o f a case 96

Class 11/1 exa mp le 96

Class III exa mp le 97

Bimaxillary prot rusio n exam ple 97

Bimaxillary retrusion  -  a Class 11/2 ex am ple 97

Mistakes in tooth leveling and al igning in the early

years 98

Reduced anchorage needs dur ing too th leve l ing

and a l ign ing 99

Bracket desig n 99

Archwire forces 99

Avoidance of elastic chain 99

A n te ro -p o s t e r io r a n c h o ra g e su p p o r t d u r in g to o lh

leveling an d al ig nin g 100

Lacebacks for A/P can ine con trol 100

Bendbacks for A/P incisor contro l 102

A/P anchorage control of lower molars - the

lingual arch 104

A/P anch orag e cont rol o f lower m ola rs - Class 111

elastics an d head gear 104

A/P anchorag e support an d control for u pper

molars - the use of headg rear 105

A/P anchorage support and control for upper

mola rs - the palatal bar 106

Ver t ica l anchorage con t ro l dur ing too th leve l ing

and a l ign in g 106

Incisor vertical co ntr ol 106

Ca nin e vertical con trol 107

Molar vertical con trol in high-a ngle cases 107

Anchorage con t ro l in the la te ra l (corona l )

p lane 108

Inter-canine width 108

M olar crossbites 108

Except ions to ful l b rack e t p lac em ent 109

Cases with unerupled teeth, or teeth significantly

out of the arch form 109

Some high-angle deep-bite cases 109

Re-leveling pro ced ure s 109

Wire sequenc ing dur ing too th leve l ing and

a l ign ing 110

1 listorical back groun d  1  10

Recomm ended sequenc ing 110

Heat -ac t iva ted n icke l - t i tan ium or s ta in less

s te e l? I l l

C l in ica l p roc edu res in leve ling and a l ig n ing -

imp rovin g pa t ien t comfo r t and accep tance 112

Case LB No n-ex tractio n average angl e case 114

Case IN First pre mo lar extrac tion case 120

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INTRODUCTION AN D DEFINITIONS Principles o f an cho rag e co nt ro l

Too th l e ve l ing a nd a l ign ing is no rm a l ly the f ir st o r t hod on t i c The re a re two ma in a s pe c t s to a nc h ora ge c on t ro l :

objec t ive during the in i t ia l s tage of t rea tment . I t may be

defined as:

The tooth movements needed to achieve passive engagement of a

steel rectangular wire of .019/. 025 dimension and of suitable

arch form, into a correctly placed preadjusted .022 bracket

system.

1. Red uct ion of anc ho rag e needs dur in g leve l ing and a l igning.

'There is a need to min im ize th e factors whic h threa te n

a n c h o r a g e a n d w h i c h p r o d u c e u n w a n t e d t o o t h

m o v e m e n t s . T h i s r e d u c e s t h e d e m a n d s o n a n c h o r a g e .

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Suc c e s s fu l t oo th a l ignme n t de pe nds on re c ogn iz ing tha t

unwa n te d too th move me n t s c a n oc c u r e a r ly in t r e a tme n t ,

ma inly ow ing to the t ip bui l t in to the preadjus ted brackets .

The s e unwa n te d too th move me n t s ne e d to be c on t ro l l e d , o r

the unde r ly ing ma loc c lus ion w i l l wors e n du r ing too th

a l ignment . This wi l l increase the t ime and effort needed to

comple te the case , la te r in t rea tment .

During leve l ing and a l igning, therefore , a l l tooth

mo ve m e n t s s hou ld be ca r r i e d ou t w i th the f ina l t r e a tme n t

goa l in mind , a nd a nc hora ge c on t ro l me a s u re s s hou ld be us e d

to res t r ic t unwanted tooth movements . In th is text , the te rm

'a nc hora ge c on t ro l du r ing too th l e ve l ing a nd a l ign ing ' w i l l

ha ve the fo l lowing me a n ing :

The maneuvers used to restrict undesirable c hanges during the

opening phase of treatment, so that leveling and aligning are

achieved withou t key features of the malocclusion becoming

worse.

Shor t - term versus long- term object ives

I t i s he lpful to cons ider leve l ing and a l igning agains t a

ba c kgro und o f s ho r t - t e rm a nd long- t e rm ob je c t ive s :

• Th e s ho r t - t e rm ob je c tive s , i n the ope n in g mon ths o f

t rea tment , wi l l be to achieve proper leve l ing and a l igning

into pass ive rec tangular s tee l wires .

• Th e long-te rm term objec t ives , to be reached by the end of

t re a tme n t , w i l l be to a c h ie ve a n ide a l de n t i t i on , s howing

the s ix keys to normal occ lus ion, and with the dent i t ion

properly pos i t ioned in the fac ia l profi le .

Experience has repea tedly shown tha t a t tempts to rush the

short - te rm objec t ives , by taking short cuts and us ing heavy

forces , cause unwanted changes to take place . These make

a c h ie ve me n t o f the long- t e rm ob je c t ive s more t ime

co ns um ing and difficul t.

2 .

  Anc hora ge s uppo r t du r in g too th l e ve ling a nd a l ign ing .

Wh ere necessary , there is a need to use anc ho rag e support ,

such as pa la ta l or l ingual bars , to he lp to control cer ta in

tee th , or groups of tee th .

Anchorage control needs wil l d i ffe r f rom case to case .

M e a s u re s to s uppor t a nc hora ge c on t ro l w i l l no t be ne e de d in

both arches , in every case . In some cases , for example in some

Class  1  and Class 11/2 cases, no special measures will be

re qu i re d , a nd too th a l ignme n t c a n p roc e e d w i thou t r e ga rd to

a nc hora ge c on t ro l . Howe ve r , mos t c a s e s do re qu i re p rope r

anc hor age contr ol , and i t i s im po rta nt to identi fy the needs

for each individual case .

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Treatment sequence to show level ing and

aligning

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Fig .  5.1A  In this very cro wd ed Class I case, th e f i rs t p rem ola rs

had prev iously been ex t ra c ted . The upper r igh t la tera l inc isor

was in c rossbite , and th ere was 2 mm o f d isp lacem ent at

term inal c losure.

F i g .

  5.1C

  Tw o mont hs la ter . The upp er r igh t la tera l inc isor

bracket was not inver ted because th e roo t pos i t io n of th is too th

w as goo d , and s pec ia l t o rque c on t ro l w as no t r e qu i r ed . A

m u l t i s tr and w i re w as used to c o n t i nue t oo th l ev e l i ng and

a l i gn ing i n t he upper , w i t h a .014 round s tee l w i r e i n t he l ow er .

F i g .

  5.1E

  Here the case is seen at com plet ion o f too th level in g

and a l i gn ing . S tee l r ec tangu la r w i r es , . 019 /025 i n d im ens ion

and of ovoid arch form, are pass ive ly engaged in a cor rec t ly

p laced preadjus ted .022 bracket sys tem.

F i g .  5.1B  I n i t i a l a l i gn m e n t w as c om m enc ed w i th a . 015

m u l t i s t r and upper a r c hw i re and a . 016 H AN T low er a r c hw i re . A

band w i th an ey e le t w as p lac ed on the upper r i gh t l a te ra l

inc isor. This was loosely   t ied .

F i g .

  5 . 1 D

  A f t er 4 mon ths of t re atm en t , i t was poss ib le to p lace

upp er and lo wer re c tan gula r .019/ .025 HANT wi res . These very

ef fec t ive w i res we re used for severa l mon ths , cha ngin g

elas tomer ic modules and re- ty ing as necessary .

F i g .

  5.1F

  The case af te r set t l ing and appl iance rem oval . Goo d

to o t h f i t w as as si sted by t he l a rge si ze o f t he uppe r l a te ra l

incisors.

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RECOGNIZING THE ANCHORAGE NEEDS

OF A CASE

At the diagnos is and t rea tment p lanning s tage for each case , a

goal wi l l be se t for inc isor pos i t ion in the fac ia l complex a t

the e nd o f t r e a tme n t . The de te rmina t ion o f th i s ' p l a nne d

inc isor pos i t ion ' or PIP is expla ined on pages 166 to 169. The

p la nne d mola r a nd c a n ine c ha nge s w i l l ha ve be e n de ie rmine d

us ing the denta l VTO.

1

Most of the concern wil l be with A/P changes , but torque

control and vert ica l i s sues need to be cons idered and property

m a n a g e d , w h e r e a p p r o p r i a t e .

Anc hora ge ne e ds fo r the mo la r s a nd c a n ine s c a n be

p re d ic t e d f rom the de n ta l VTO. The s e t e e th s hou ld s ho w no

change , or preferably favorable change , re la t ive to the VTO

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The anchorage control needs of a case , ear ly in t rea tment ,

c a n be de c ide d by c ompa r ing the s t a r t ing pos i t ion o f uppe r

a nd lowe r inc i s o rs w i th PIP a t t he e nd o f t r e a tme n t . Dur ing

too th l e ve l ing a nd a l ign ing , t he a nc ho ra ge c on t ro l s hou ld be

ma na ge d to e ns u re tha t t he uppe r a nd lowe r inc i s o rs e i the r

show no change , or they should move favorably re la t ive to

PIP.

  Ideal ly , inc isor movement should be favorable , re la t ive to

PIP,

  th rou gho u t l e ve l ing a nd a l ign ing , t he re by re duc ing the

a moun t o f too th move me n l ne e de d l a t e r i n the t r e a tme n t .

r e q u i r e m e n t s .

In the fol lowing examples , the inc isor s ta r t ing pos i t ion is

s hown in b l a c k , w i th the PIP in g re e n , a nd c omme nts a re

offered concerning the l ike ly needs of the case . Every

or t ho do n t i c c a s e w i l l be d i ffe re n t, a nd the a nc hor a ge c on tro l

ne e ds w i l l be de te rmine d by the pos i t ion o f the inc i s o rs

re la t ive to PIP, an d not by th e Angle 's c lass if ica t ion of the

mola r s .

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Class  11/1 example

At the s ta r t of t rea tment , the upper inc isors a re normal ly in

front of PIP, and ful l A/P anc hor age con trol wi l l be req uired

to res t r ic t mes ia l movement and an increase in overje t . As

discussed la te r in th is chapter , upper a rch anchorage control

w i ll i nvo lve l a c e ba c ks a nd b e ndb a c ks , a nd ma y re qu i re

support f rom a pa la ta l bar , a headgear , or Class II e las t ics .

Lower inc isors wi l l normal ly be on or behind PIP.

Anc hora ge w i l l ne e d to be ma na ge d to p re ve n t undue

pro cl ina t ion du rin g a l ig nm ent . As with m os t cases, care wil l

be needed to avoid excess ive archwire forces , to e l iminate the

r isk of a ' ro l le r coas ter ' e ffec t and deepening of the overbi te .

F i g .

  5.2 Class Il/l

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Class III e xa m ple

In th is example, the upper incisors are beh ind PIP al the s tar t

o f t reatment , a l though in o ther Class I I I cases they may be on

PIP or even in f ron t o f i t . Lacebacks an d be ndb ac ks w i l l

therefore be con t raind icaied in the upper arch in many Class

III cases , to a l low upp er incisors to p rocl in e and sho w

favorab le to rque changes towards I ' l l ' , and to al low upper

a rch d ev e l o p men t .

Anchorage con t ro l wi l l on ly be needed i f there i s a r i sk o f

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o v erp ro d u c t i o n o f t h e u p p er i n c i so r s , b ey o n d t h e P IP .

Lower in ciso rs will typica lly be in front of PIP in a Clas s 111

case. Th e lowe r arch wi ll therefore n orm al ly requ i re ful l

an ch o rag e co n t ro l wi t h b en d b ack s an d l aceb ack s , p o ss i b l y

suppor ted wi th a l ingual arch and /or Class I I I e las t ics .

Bimaxi l la ry prot rus ion example

Normal ly fu l l anchorage con t ro l wi l l be requ i red in bo th

arches fo r th is type of case, because upper and lower incisors

will be in front of PIP at the start of tre atm en t.

In terest ing ly , the mesial iz ing ef fect o f b racket t ip o f ten

d o es n o t co me i n t o p l ay i n t h ese cases , b ecau se t h e c ro wn s

are l ipped mesial ly at the s tar t . Desp i te th is , fu l l anchorage

cont ro l i s normal ly appropr iate in the ear ly s tages , to ensure

o p t i ma l r e t r ac t i o n o f t h e an t e r i o r seg men t s .

F i g .  5.3 Class

F i g .

  5 .4 B im ax i l la r y p ro t r us ion

Bimaxi l lary  re t rus ion -  a Class 11/2

example

In these cases,  it  is of ten  a t r ea t m en t r eq u i r em en t t o a l l o w

u p p er  an d l o wer i n c i so r s u n res t r i c t ed mes i a l mo v emen t i n

r esp o n se t o t h e o p e n i n g a r ch wi res . T h ere fo re l aceb ack s an d

b en d b ack s may b e d i sp en sed wi t h , so t h a t an t e r i o r b r ack e t t i p

can express

  itself.

T h e s t a r t i n g mal o cc l u s i o n o f t en h as can i n es wh i ch a r e

t ipped d is ta l ly - an ind icat ion for very l igh t open ing archwire

forces . Favorab le an ter io r to rque and ver t ical changes typ ical ly

occur in these cases , ear ly in t reatment , and they are o f ten no t

d i f f icu l t to manage in anchorage terms.

F i g .

  5. 5 Class 11/2

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MISTAK ES IN TOOTH LEVELING A ND

ALIGNING IN THE EARLY YEARS

The tip built into the anterior brackets of the preadjusted

appliance system caused considerable difficulties in the early

years. The tip caused the crowns of the anterior teeth to

incline forward during the initial phase of leveling and

aligning (Fig. 5.6).

Early attempts were made to eliminate or minimize this

effect by connecting an terior segments to posterior segmen ts,

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usually with elastic forces. But this created a greater demand

for anchorage control during this initial stage of treatment.

Also, if the elastic forces were greater than the leveling force of

the archwire, there was a tendency for anterior teeth to tip

and rotate distally, increasing the curve of Spee and

deep ening the bite. This was particularly evident in first

premolar extraction cases, and was referred (o as the 'roller

coaster' effect (Figs 5.7-5.9).

The 'roller coaster' effect is seldom seen in today's cases,

owing to the reduced tip in the MBT™ bracket system, lighter

archwire forces, and use of lacebacks for canine control

instead of elastic chain.

F i g .

  5 .6 The t i p bu i l t i n to t he an te r i o r b rac k e ts o f t he

p read ju s ted app l i anc e s y stem causes the c row ns o f t he an te r i o r

t ee th t o i nc l i ne f o rw ard du r ing ea r l y l ev e l i ng and a l i gn ing .

a - i S - .  '• •

 : -. \ :: . :-: &

F i g .

  5.7

F i g .

  5 .8

F i g .

  5 .9

F i g .

  5 .7 to 5.9 Use of e las t ic force for canine ret ra c t io n, and excess force gene ra l ly , produces a tend ency fo r deep en ing of t he

an te r i o r b i t e . A l s o , t he re is a t endenc y t o l a te ra l ope n b i t e , t he ov e ra l l ou t c om e be in g re fe r red to as t he ' r o l l e r c oas te r ' e f f ec t . I n

t rea tme nts in th e 1970s and 1980s, the ef fec ts of e las tic forces ap pl ie d to canines ear ly in ex t r ac t io n t rea tm en t w i t h l ig ht arch wires in

p lace w e re f ou nd to b e : ( a) t i pp ing and ro ta t i o n i n to e x t r ac t i on s i tes ; ( b ) b i t e ope n ing i n t he p rem o la r r eg ions ; ( c) b i t e de epe n ing

an te r i o r l y .

98

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REDUCED ANC HORAGE NEEDS DURING

TOOTH LEVELING AND ALIGNING

Where possible, the anchorage needs of

 a

  case should be

reduced. This will lessen the need for anchorage control and

support measures such as palatal and lingual bars or

headgears, and this in turn will simplify the treatment and

may make fewer demands on patient cooperation. The

measures described below have been found to reduce

demands on anchorage and thereby improve treatment

Arch w ire forces

The use of veiy light archwire forces (p. 112) early in

treatment will be more comfortable for the patient, and will

put less demand on anchorage. When unsure about which of

two wires to use, it is normally preferable to use the lighter

one.

  There is also a need to avoid changing wires too

frequently.

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efficiency.

Bracket design

Bracket tip is the major factor in anchorage demands early in

treatment. Any reduction in built-in lip is beneficial in

reducing the anchorage needs of a case. The MBT™ V eisatile+

bracket system is based on the original research values for lip.

A  total of 10° less distal root tip in the upper anterior

segment and 12° less distal root lip in the lower anterior

segment is needed, compared with the original SWA

(Fig. 5.10). This reduces the anchorage needs, lessens the

tendency to bite deepening in the early stages, and puts less

demand on patient cooperation.

Avoidance of e last ic chain

As previously discussed (p. 98), m any problem s in the past

emanated from the use of elastic retraction mechanics,

especially in first prem olar extraction cases. These sho uld be

avoided.

0° 0' 8° 4"

2"

  2°

  3" 0" 0"

SWA t ip MB T" t ip

F i g .

  5 .10

  The MBT™ bracke t sys tem has 10" less d is ta l root t ip in the u ppe r ant er io r segm ent an d 12° less d is ta l root t ip in the lower

anter ior segme nt comp ared w i th SWA. This is bene f ic ia l in redu c ing anch orage dem ands ear ly in t re atm en t .

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ANTERO-POSTERIOR ANCHORAGE

SUPPORT DURING TOOTH LEVELING AND

ALIGNING

Lacebacks for A/P canine control

Lacebacks

2

  are .010 or .009 l igature wires which ex tend f rom

t h e mo s t d i s l a ll y b an d ed mo l a r t o t h e can i n e b rack e t

(Figs 5 .11 & 5 .12) . They res t r ic t can in e crow ns f rom l ipp in g

forward d ur in g level ing and al ig n ing . They are ma in ly used in

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premoiar ex t ract ion cases , bu t they may also be requ i red in

some non-ex t ract ion cases where there i s a local th reat to

anc hor age . For exa mp le, i f the roo t o f a can in e i s mesial ly

plac ed (Fig. 6. 21 , p. 1 40), this will effectively incr ease th e t ip

in the can ine bracket a t the s tar t o f t reatment , and hence

i n c rease t h e an ch o rag e n eed s o f t h a t t o o t h .

Lacebacks are passive dev ices , and should no t be

over t igh tened to an ex ten t that t i ssue b lanch ing occurs . They

are p laced before the archwire. At month ly ad justment v is i t s ,

the lacebacks are normal ly loose, and requ i re 1 -2 mm of

l igh ten ing .

F i g .  5 .11  .010 or .009 l igature w i res are used fo r canine

lacebacks , which are used main ly in premoiar ex t rac t ion cases .

100

F i g .

  5 .12

  Lacebacks have been an in te gra l par t o f the auth ors ' t re atm en t ph i los ophy fo r many years . This f i rs t prem oia r ex t r ac t io n

case, t re ate d in the 1980s w i th o r ig in a l SWA, shows upper an d low er lacebacks in p lace. Lacebacks may be t ie d ro un d the mo lar

a t t ac hm ent o r f r om th e m o la r hoo k . If t i ed r ound th e m o la r a t t ac h m en t , i t is o f t e n nec es sary t o use an ex p lo re r t o p rev en t t he

laceback b lock ing the d is ta l aspec t o f the molar tube.

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UT

Bendbacks for A/P incisor control

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These are used as an important method of anchorage support,

often in combination with lacebacks. If the archwire is bent

back immediately behind the tube on the most distally

banded molar, this serves to minimize forward lipping of

incisors (Fig. 5.16 A-C).

If the opening wire is .015 multistrand, it may be turned

into a small circle distal to the molar tube (Fig. 5.17).

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F i g .  5 .1 6 B

  S tee l and H AN T w i res s hou ld hav e the t e rm ina l 3

m m f l a m e d a n d q u e n c h e d b e f o r e p l a c e m e n t .

F i g .

  5 .1 6 A  Bendbac k s a re an im p or ta n t m e tho d o f anc horag e

s uppor t and c an m in im iz e f o rw ard t i pp ing o f i nc i s o r s .

F i g .

  5 .16C  The s o f t ened en d o f t he a r c hw i re c an eas i ly be

tu r ne d i n t o f o r m a bend bac k . The s o f t e n ing fac i l i t a tes r em ov a l

o f t he a r c hw i re a t t he s ubs equen t ad jus tm en t v i s i t .

102

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F i g .

  5.17

  M u l t i s t r a nd w i res m ay be c a re fu l l y t u rn ed i n to a

smal l c i rc le d is ta l to the molar tube to c reate a bendback .

The ends of the  .016  HANT wires and roun d steel wires

need  10 be (lamed and quenched  in cold water before

placement, to allow accurate bendbacks (Figs 5.18 & 5.19).

The rectangular HANT wires may be thin ned at their term inal

3 mm and then flamed and qu enche d, to avoid de-bo nding

bonded m olar tubes when creating bendbacks (Fig. 5.20) an d

to facilitate removal of the archwire for adjustment.  A green

stone is used for the thinning.

Like lacebacks, bendbacks are normally continued

throughout the leveling and aligning archwire sequence, up to

and including  th e rectangular HANT stage, for any case which

requires A/P control of incisors. Later, in the rectangular steel

wire  stage, the A/I' control is continued with passive tiebacks

(Fig. 9.17, p. 255, and Fig. 7.59, p. 186).

In cases where  it  is necessary  to  increase arch length during

leveling and aligning (p. 40), and where A/P incisor control is

not required,  bendbacks sho uld be placed I or 2 m m  distal  to

molar tubes (Fig. 7.16C, p. 171).

F i g .

  5 .18

  Bendbacks are poss ib le wh en u s ing .016 HANT wi res ,

p rov id in g t he t e rm ina l 3 m m is f l am ed and que nc he d i n c o ld

w a te r be fo re p lac em ent o f t he a r c hw i re .

F i g .

  5 . 1 9

  I t is he lpf u l to f lame the en d of a l l archwire s , except

s tee l r ec tangu la r and m u l t i s t r and w i res , and then quenc h them

in co ld wa ter be fore p lace men t . This a l low s accurate bendba cks .

F i g .  5 . 2 0  R ec tangu la r H AN T w i res m ay be th in ne d a t t he i r

t e rm in a l 3 m m to a l l ow c rea t i on o f bendbac k s a f t e r f l am ing

a n d q u e n c h i n g .

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A/P a n c h o r a g e c o n t r o l o f l o w e r m o l a r s -

the l i ngua l a r ch

Soldered l ingual a rches may be used in the la te mixed

den t i t io n in cases with m ild lower a rch crow ding . Th e lower

f i rs t molars wi l l normal ly dr i f t mes ia l ly in to the leeway space

from the shedding of the lower pr imary second molars (Figs

5.21 & 5.22 ) . This can be res tr ic ted by the t imely p lace me nt

of a l ingual a rch, and the space used to ass is t lower anter ior

a l ignme n t du r in g too th l e ve l ing a nd a l ign ing .

Lingua l a rc he s s hou ld a l s o be c ons ide re d fo r ma x im um

+ 2.5 mm

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anc hor age pre mo lar extrac t ion cases. This wi l l inc lu de m any

bimaxi l la ry proc l ina t ion cases and a lso cases with severe

lower anter ior c rowding. In both these types of problem, i t i s

necessary to cons ider us ing a l ingual a rch throughout the

early stages of leveling and aligning. This will restrict the

me s ia l move me n t o f lowe r mo la r s , a nd in the b ima x i l l a ry

proc l ina t i on cases , it wi l l ensu re tha t mos t of the p rem ola r

extrac t ion sp ace is ava i la ble a t the end of leve l ing a nd

al igning, to provide for re t rac t ion of the anter ior segment . In

the severe ly crowded cases , the l ingual a rch wil l ensure tha t

mos t of the premolar extrac t ion space is used to re l ieve

a n te r io r c rowding (C a s e IN , p . 120) .

A/P a n c h o r a g e c o n t r o l o f l o w e r m o l a r s -

Class I I I e last ics and headgear

In c a s e s w i th s e ve re lowe r a n te r io r c rowding , whe re more

a nc ho ra ge s uppo r t i s ne e de d tha n c a n be p rov ide d by a

l ingual a rch a lone , Class III e las t ics can be worn to Kobayashi

t ie wires in the lower canine region, a t the same t ime as a

headgear (Fig . 5 .23) . The authors prefer to de lay Class III

e las t ics unt i l the .016 round wire s tage , to prevent extrus ion

of the inc isors . Fortunate ly , few cases require th is amount of

lowe r a rc h a nc hora ge s uppor t .

F i g .  5 . 2 1

  Low er l ingu al arches may be used to prev en t f i rs t

m o la r s d r i f t i ng m es ia l l y i n to t he av a i l ab le l eew ay s pac e a f t e r

s hed d ing o f t he l ow e r p r im ary s ec ond m o la r s . Th is av e rages

2.5 mm.

F i g .  5 .2 2

  So lde red l i ngua l ar c hes a re he lp fu l i n m a x im u m

anc ho rage p rem o la r ex t r ac t i on cases du r ing t oo th l ev e l i ng a nd

a l i g n i n g .

  They no rm a l l y need to be rem ov ed p r i o r t o s pac e

c losure. They are a lso usefu l in protec t ing leeway space, as

s how n in t h i s non-ex t rac t i on c as e .

104

F i g .  5 .2 3

  C lass I II e las tics can be w o rn in co mb ina t io n w i t h a

h e a d g e a r f o r m a x i m u m a n c h o r a g e s u p p o r t i n t h e l o w e r

an te r i o r s egm ent .

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A/P anchorage supp ort and cont ro l fo r

upper molars - the use of headgear

In cer tain cases , i t may be necessary fo r the upper poster io r

seg men t s t o b e l i mi t ed in t h e i r mes i a l mo v em en t , ma i n t a i n ed

in thei r posi t ions , o r even d is ta l ized , to a l low the an ter io r

segments to be p roper ly posi t ioned in the face. Poster io r

an ch o rag e co n t ro l r eq u i r emen t s a r e n o rmal l y g rea t e r i n t h e

upper arch than in the lower arch owing to f ive main factors :

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1 . The upper molars move mesial ly more easi ly than the

l o wer mo l a r s .

2.

  The upper an ter io r segment has larger teeth than the lower

an t e r i o r seg men t .

3.  T h e u p p er an t e r i o r b r ack e t s h av e mo re t i p b u i l t i n t o (h em

than the lower an ter io r b rackets .

~~Occlusal plane

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F i g .  5 .24

4.

  T h e u p p er i n c i so r s r eq u i r e mo re t o rq u e co n t ro l an d b o d i l y

mo v emen t t h an t h e l o wer i n c i so r s , wh i ch o n l y r eq u i r e

d is tal t ipp ing or upr igh l ing .

5.  In many pract ices in America and Europe, a typ ical

caseload has more Class I I type of malocclusions than

Class III type.

Because of these factors, extra-oral force is normally the

most ef fect ive method of poster io r anchorage con t ro l  in  the

upper arch , p rov ided suff ic ien t pat ien t coope rat i on i s

avai lab le . The th ree p r im ary types o f facebow he adge ar an d

thei r fo rce d i rect ions are shown (Fig . 5 .24) .

T h e au t h o r s f av o r a co mb i n a t i o n h ead g ear (o cc i p i t a l p u l l

and cervical pul l) in m os t cases. The force levels used for the

co m b i n a t i o n h ead g ear a r e 1 5 0 -2 5 0 g m fo r t h e o cc ip i t a l p u l l

an d 1 0 0 ~ 1 5 0 g m fo r t h e ce rvi cal p u l l . T h es e force v a l u es a l l o w

for s l igh t ly s t ronge r pu l l on th e occip i ta l co m po ne nt o f the

headgear , keep ing forces d i rected s l igh t ly above the occlusal

p l a n e a n d m i n i m i z i n g  t h e  tendency for ver t ical ex t rusion of

t h e u p p er p o s t e r i o r t ee t h , wh i l e s i mu l t an eo u s l y a l l o wi n g

effective distalization of the molar.

T h e l en g t h o f t h e o u t e r b o w o f t h e h ead g ear i s i mp o r t an t

to  av o id u n w an t e d m o l a r l i p p i n g . It sh o u l d en d ad j acen t t o

th e  uppe r f i rs t mo lar (1- ig . 5 .25 ) . An ex tende d ou ter bo w or a n

o u t e r b o w b en t d o wn ward p ro v i d es a g r ea t e r t en d en cy fo r

d is tal t ipp in g of the crow n of the f i rs t mola r . A sho r ter o u te r

bow, o r t ipp ing up of the ou ter bow, causes a g reater

tendency for the roo ts to be d is ta l ized ahead of the crowns, as

shown in the i l lus t rat ion . In h igh-angle cases where l i t t le

d is ta l izat ion of the molar i s requ i red , an occip i ta l headgear

alone can be used . In very low-angle cases , where musculature

is s t ro n g en o u g h t o m i n i m i ze v e r ti cal ex t ru s i o n o f t h e

poster io r teeth , a cerv ical headgear a lone can be considered .

F i g .  5 .25 Th is d iag r am s how s the t heore t i c a l e f f ec t o f

v a r i a t i ons i n t he l eng th o f t he ou te r a rm o f t he headgear bow .

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A / P a n c h o r a g e s u p p o r t a n d c o n t r o l f o r

up pe r m o la rs - t he pa la ta l ba r

A seco n d m ei h o d o f an ch o rag e su p p o r t i n t h e u p p e r p o s t e r i o r

segm ent i s the palatal bar . Th is i s nor ma l ly p laced wh en the

upper molars have been proper ly ro tated and are s i tuated in a

C l ass I r e l a t i o n sh i p t o t h e l o wer mo l a r s .

The palatal bar can be const ructed of heavy .045 or .051

inch (1 .1 o r 1 .3 m m ) rou nd w ire ex te ndin g f rom m ola r to

molar wi th a loop p laced in the middle o f the palate and the

wire ab out 2 m m from th e roof o f the palate (F ig, 5 .26 and

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5 .29 ) . It i s so lde red to the m olar b an ds .

VERTICAL ANCHORAGE CONTROL

DURING TOOTH LEVELING AND ALIGNING

F i g .  5 .26  Sold ered pal ata l bars are he lp fu l in restr ic t ing mesial

m ov e m en t o f upper m o la r s du r ing t oo th l ev e l i ng and a li gning .

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Ver t i ca l con t ro l o f t he i nc i so rs

As prev ious ly d iscussed , an ter io r co n t ro l is needed to res t ric t

the tendency to temporary increases in overb i te (F ig . 5 .27) ,

especial ly in dee p-b i te cases . The effect o f b racket t ip i s m ore

ex t r eme i n t h e u p p e r a r ch , an d ca re i s n eed e d i f t h e can i n es

are d is ta l ly l ipped in the s tar t ing malocclusion . In such cases ,

as the archwire passes th rough the can ine bracket s lo t i t wi l l

lay incisally to the incisor bracket slots. If the wire is fully

engaged in to the incisors , i t wi l l tend to cause ex t rusion of

these teeth , which i s und esi r ab le in mo st cases .

This ef fect can be avo ided ei ther by no t b racket ing the

incisors a t the s tar t o f t reatment , o r by no t ty ing the archwire

into the incisor bracket slots, but allowing i t to lay incisally to

t h e b rack e t s u n t i l t h e can i n e ro o t s h av e b een u p r i g h t ed an d

mo ved d is tal ly , und er the con t ro l o f the lacebacks. The

i n c i so r s can t h en b e en g ag ed wi t h o u t cau s i n g u n w an t e d

ex t ru s i o n .

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F i g .  5 .27 The t ip wh ich is bu i l t in to the ante r ior brackets of the pre adjus te d appl iance sys tem gives a tend enc y to tem po rary

increas es i n ov e rb i t e ea r l y i n t r ea tm en t . I f t he c an ines a re d i s ta ll y t i ppe d i n t he s ta r t i n g m a loc c lus ion , t he n th e b i t e -de epe n ing e f f ec t

is gre ater .

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Ver t i ca l con t ro l o f  can ines

It  is  important to avoid early archwire engagem ent of high

labial canines (Case JN, p. 121), so that unwanted vertical

movement of lateral incisors and premolars does not occur

(Fig. 5.2 8).

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F i g .  5 . 2 8

  H igh l ab ia l c an ines m ay be l oos e ly t i ed t o t h e . 015 m u l t i s t r and o r . 016 H AN T w i re i n t he ea r l y s tages o f t r ea tm e n t . I f t he

s ta r t i ng a r c hw i re is f u l l y engag ed i n t he c an ine b rac k e t s lo t , i t can p roduc e un w a n te d to o t h m ov e m en ts i n t h e ad jac en t l a te ra l

inc isor and premolar reg ions .

Ver t i ca l con t ro l o f mo la rs i n h igh -ang le

cases

When treating high-angle cases, the following me thod s of

vertical molar control should be considered:

• Upper second molars are generally not initially ban ded or

bracketed, to minim ize extrusion of these teeth. If they

require banding, an archwire step can be placed behind

the first molar to avoid extrusion.

• If the tipper first mo lars require expa nsion, an attem pt is

made to achieve bodily movement rather than tipping, to

avoid extrusion of the palatal cusps. This is best

accomplished with a fixed expander, sometimes

combined with a high-pull headgear.

F i g .  5 .2 9

  I f the up per p a lata l bar is p laced 2 mm aw ay f r om

th e pa late, to ng ue forces can ass is t in ver t ica l con t ro l o f th e

molars .

• If palatal bars are used, they are designe d to lie away

from the palate by approxim ately 2 mm so that the

tongu e can exert a vertical intrusive effect (Fig. 5.29).

• When headgears are used in high-an gle cases, either a

combination pull or a high-pull headgear is used. The

cervical pull headgear is avoided.

• In som e cases, an upp er or lower poster ior bitep late in

the molar region is helpful to minimize extrusion of

molars.

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ANCHORAGE CONTROL IN THE LATERAL

(CORONAL) PLANE

In most cases, no special care is needed to maintain lateral

anchorage control. However, attention needs to be paid to

inter-canine width in all treatments, and molar crossbites are

important in certain treatments.

In ter-can ine wid th

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Upper and lower inter-canine width should be kept as close as

possible to starting dimensions for stability, and care should

be taken to ensure that crowding is not relieved by

uncontrolled expansion of the upper and lower arches.

Molar crossbites

Care is needed to avoid arbitrary correction of molar

crossbites by lipping movements. This allows extrusion of

palatal cusps and unwanted opening of the mandibular plane

angle in treatment of high-angle, and even routine, Class 11/1

problem s. Whenever possible, molar crossbites should be

corrected by bodily movement.

An assessment of maxillary bone can be made, and if it is

too narrow, early rapid expansion sh ould be considered as a

separate procedure prior to leveling and aligning. If adequate

maxillary bone exists, a fixed qtiadhelix expander can be

effectively used. Minimal molar crossbites can usually be

corrected in the final stage of leveling and aligning using

rectangular wires which are slightly expanded from the

normal form (Fig. 5.30).

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Problem

• . ■ •

F i g .  5 .30 Uppe r mola r expans ion shou ld be car r ied out by

bod i l y m ov em ent r a the r t han t i pp ing . M in im a l m o la r c ros s b i t es

can be cor rec ted us ing rec tangular s tee l w i res which are s l ight ly

ex panded f r om the no rm a l f o rm and w h ic h c a r r y buc c a l r oo t

t o r q u e .

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EXCEPTIONS TO FULL BRACKET

PLACEMENT

i/i

Placement of brackets or bands on a l l poss ible tee th is

recom men ded a t the s ta r t of mos t t rea tme nts . This a l lows for

the ear l ies t poss ible s tabi l iza t io n of a rch form, and a lso h e lps

control the cuspids . However, there a re except ions to ful l

bracket p lacement .

Cases w i t h un eru pte d tee th, or tee th

roo t pos i t ion ing , r e duc ing the t r e a tme n t ne e ds in the

finishing phase.

High-angle deep-bite cases in which the

upper inc isors in ter fere wi th bracket

p lacement on the lower inc isors

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signif icant ly out of the arch form

Such tee th can be le f t unbracketed unt i l adequate space is

p rov ide d fo r the i r move me n t a nd pos i t ion ing (F ig . 5 .31 ) .

Once space is c rea ted, the se tee th can be bracketed a nd l ighl ly

t ied with e las t ic thread to the main archwire . Suff ic ient space

mus t be ope ne d fo r move me n t o f in s t a nd ing t e e th s o tha t

the y do no t fu l c rum a t t he c on ta c t a re a , c a us ing im pro pe r

roo t pos i t ion ing . The c re a t ion o f a de qu a te s pa c e a l lows b od i ly

mov emen t of these tee th in to the arch form an d m ore correc t

These cases a re unus ual , b ut whe n th ey occur , the u pp er

inc isors can be bracketed and the lower inc isors le f t

unbracketed a t the s ta r t of t rea tment . After leve l ing and

al igning have occurred in the upper a rch for 2 to 3 months

a nd the uppe r inc i s o rs ha ve be e n s l igh t ly a dva nc e d , t he lowe r

inc i s o rs c a n the n be b ra c ke te d . Th i s p re ve n t s unne c e s s a ry

e x t rus ion o f pos t e r io r t e e th du r ing the l e ve l ing p roc e dure . In

low-angle deep-bi te cases , a b i tepla te can be placed a t the

in i t i a l bond ing v i s i t , p rov ide d the oc c lus ion a l lows th i s .

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F ig .

  5 .3 1  Tee th w h ic h a re s ign i f i c an t l y ou t o f t he a r c h f o r m s hou ld be l e f t unb rac k e ted un t i l adequ a te space is p rov id ed fo r t h e i r

mo vem ent and p os i t ion ing . The above examp les sho w space be ing c reate d for lo we r canines (Case LB, p. 116) an d upp er ca nines

(CaseTC, p. 192).

RE-LEVELING PROCEDURES

I t i s necessary to repea l leve l ing and a l igning procedures in

many cases when us ing preadjus ted appl iances . Re-leve l ing is

needed when newly erupted tee th a re inc luded for the f i rs t

t ime , o r whe n b ra c ke t a nd ba nds a re re -c e me n te d , e i the r

because of breakage or incorrec t or ig ina l pos i t ioning. During

trea tment , re - leve l ing should be carr ied out as few t imes as

poss ible for t rea tment e ff ic iency, but even experienced

clinicians can fail to place all brackets accurately at their first

a t tempt . During ear ly leve l ing and a l igning, these errors can

be ident i f ied , an d i t is be t te r to repos i t ion b rackets ra ther tha n

ma k ing a rc hwi re be nd s th ro ugh ou t s ubs e q ue n t t r e a tme n t .

Inc o r re c t ly pos i t ione d b ra c ke t s c a n be re pos i t ione d whe n

newly erup ted or poo rly pos i t ion ed tee th a re bracke ted for the

f i rs t t ime, because i l i s necessary to re turn to l ighter a rchwires

to pick up the se tee th . Also, i f seco nd mo lars hav e not b een

banded unt i l a f te r a s tage of t rea tment such as space c losure

or overje t reduc t ion, brackets can be repos i t io ned a t t he

second molar banding vis i t . In th is way, re - leve l ing can occur

wi th ou t lo s s o f t r e a tme n t t ime .

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WIRE SEQUENCING DURING TOOTH

LEVELING AND ALIGNING

H i s to r i c a l b a c k g r o u n d

Round and rec tangular s tee l a rchwires were used with the

s t a nda rd e dge wis e a pp l i a nc e a nd du r ing the e a r ly ye a rs w i th

the preadjus led appl iance . Round s tee l wires were used in

s izes .014, .016, .018, and .020.

Rectangular s tee l wires were ava i lable in a number of s izes ,

w i t h . 0 1 8 / 0 2 5 , . 0 1 9 / . 0 2 5 , a n d . 0 2 1 5 / . 0 2 5 b e i n g t h e m o s t

.014

.016

.018

.020

.019/.025

w

.014

F i g .  5 .32 Round and rec tan gu lar s tee l w i res we re used du r in g

the ea r l y yea rs w i th t he p read jus ted app l iance .

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pop u la r w i re s u s e d w i th the .022 b ra c ket s lo t . Th e a u tho r s

prefer the .022 s lo t over the .018 s lo t , pr imari ly because of

(he r ig idi ty needed in the a rchwire during space c losure with

s l id ing me c ha n ic s .

Th e .014 , .016 , .018 , a nd the n .020 round wi re s e que nc e

wa s us e d by the a u tho rs , fo l lowe d by the .019 / .025

rectangular steel wire (Fig. 5.32), This wire allows for efficient

s l id ing me c ha n ic s , un l ike the l a rge r .0215 / .025 wi re , wh ic h

crea tes excess fr ic t ion during space c losure . Also, the

.01 9/ .0 25 rec tang ular wire sho ws less deflec t ion t han the

m or e f lexible .01 8/ .0 25 wire .

One o f the e a r ly a t t e mpts a t p roduc ing a rc hwi re s w i th

grea ter f lexibi l i ty involved twis t ing together s t rands of very

small s tainless steel wires (l- ' ig. 5.33). These were referred to as

mult is t rand wires . These wires , in s izes .015 and .0175, were

used as in i t ia l wires , pr ior to the use of the .014 round s tee l

wire , in cases with s ignif icant tooth ma la l ig nm ent .

.Oi;

.0175

F i g .  5 .33 Mu l t i s t rand w i res w e re p roduced to in t roduce

greater f lex ib i l i ty . They are current ly used as in i t ia l w i res in

cases w i th s ign i f i can t to o t h ma la l ignm en t .

R e c o m m e n d e d s e q u e n c i n g

The in t roduc t ion o f n i c ke l - t i t a n ium wi re s p rov ide d a pos s ib l e

subs t i tu te for mul t is t rand and s tee l round wires during the

le ve l ing a nd a l ign ing s t a ge s o f t r e a tme n t . One n ic ke l t i t a n ium

wire could be used in place of approximate ly two s izes of

s ta inless s tee l wires . However, g iven the ir h igher cos t , the ir

s ign if i c anc e wa s c ons ide re d que s t iona b le by ma n y c l in i c i a ns .

They were a lso mis take nly used duri ng proc edur es tha t

required the r ig idi ty of a rec tangular s ta inless s tee l wire , such

as comple te a rch leve l ing, overbi te control , space c losure , and

overje t reduct ion with in ter-maxi l la ry e las t ics .

The de ve lopme n t o f c oppe r n i c ke l - t i t a n ium wi re s , r e fe r re d

to as 'hea t-ac t iva ted ' wires , provided wires wi th s ignif icant ly

greater flexibility. As a result, these wires could be used as a

subs t i tu te for three of the t radi t ional s ta in less s tee l wires in

c e r t a in s i tua t ions , wh ic h wa s a s ign if i c a n t imp rov e m e n t .

Ins tead of replac ing wires on a per v is i t bas is during leve l ing

a nd a l ign ing , a c oo la n t c o u ld be a pp l i e d to the he a t -a c t iva te d

nick el- t i ta nium (HAN'T) wire in the a reas w he re ful l bracke t

e nga ge me n t ha d no t be e n a c h ie ve d , a nd the w i re c ou ld be

re ti e d fo r c om ple te e nga ge me n t . The no rm a l wa rm th o f the

ora l cavi ty pro duc ed s ignif icant ac t iv a t ion of the wire- and very

e f f i c i e n t l oo th move me n t . Su rp r i s ing ly , pa t i e n t s d id no t s e e m

to c ompla in o f a dde d d i s c omfor t , p roba b ly be c a us e o f the

l ight forces tha t were in t roduced.

The a rc hwi re s e qu e nc e s ho wn (F ig . 5 .34 ) ha s be e n

e m ploy e d by the a u th o rs . I t ha s s ign i f i ca n t ly re duc e d

chairs ide l ime and increased the eff ic iency of tooth

m o v e m e n t , o w i n g 10 t h e m i n i m i z i n g o f p e r m a n e n t a r c h w i r e

deflec t ion.

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B i a H a a i H a B M

.015 .0175

SEQUENCE A

.014

016

.018 .020

.019/.025

.014

.016

HANT

.019/.025

HANT

.019/.025

.014

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SEQUENCE B

F i g .  5 .3 4

  I n s om e cases, t he au tho rs c an fo l l ow s equenc e B to c om p le te a t r ea tm e n t w i t h v e r y e f f i c i en t m ec han ic s and few a r c hw i re

changes . How ever , in many t re atm ent s i t is necessary to use some wi res f ro m the m ore t ra d i t ion al sequence A, and these are

discussed below.

HE AT-ACTIVATED NICKEL-TITANIUM

(HANT) OR STAINLESS STEEL?

Because of their flexibilily, there are clinical s ilualions where

he a t -a c t iva te d w i re s a re no t r e c omme nde d , o r whe re s ome

s ta inless s lee l wires should a lso be used. These c l in ica l

s i tua t ions a re de s c r ibe d be low :

• Initial wires in cases with severe malalig nirie nt of teet h.

I t i s a service to the pa t ient to p lace a mul t is t rand wire as

the f irst wire in such cases . Th e perm an en t deflec t ion tha t

occurs wi th these wires reduces the overa l l force leve ls and

produces less d iscomfort during the in i t ia l 'experience with

b ra c e s' . A l s o, s om e wi re be nd in g in a dd i t io n t o the n o rm a l

arch form ma y be required , and is eas i ly accom plish ed

with mult is t rand wires .

Fo r c omple te a rc h l e ve l ing a nd ove rb i t e c on t ro l .

While hea t-ac t iva ted wires a re exce l lent for individual

tooth a l ignment , they are not e ffec t ive for comple te a rch

le ve l ing a nd s ubs e que n t b i t e ope n ing . He nc e , t he

trans i t ion from even the rec tangular hea t-ac t iva ted wires

to the rec tangular s ta inless s lee l wire is somet imes

imp oss ib le . A .020 r ou nd s tee l wire is of ten require d

before the rec tangular s ta inless s tee l wire .

For torque control . Rectangular hea t-ac t iva ted wires

c omme nc e the p roc e s s o f to rque c on t ro l , bu t t h i s d i f f i c u l t

too th mo ve m e n t i s be s t c omple te d by us ing a re c t a ngu la r

stainless steel wire.

When us ing lacebacks for cuspid re t rac t ion in c rowded

extrac t ion cases . Th e use of lacebacks min im ize s th e

t ipping of the cuspids in to the extrac t ion s i tes . However ,

wi th prolonged use of f lexible hea t-ac t iva ted wires , some

t ipping can occur . To reduce th is poss ibi l i ty , a .018 or .020

s ta inless s tee l wire should be used as ear ly as poss ible

whe n us ing l a c e ba c ks .

W he n us ing ope n c o i l s p r ing in the a n te r io r o r pos t e r io r

segments to c rea te space for b locked-out tee th . Because of

the ir f lexibi l i ty , the use of open coi l spr ings on hea t-

ac t iva ted wires can cause s ignif icant d is tor t ions in a rch

form. Thus , op en coi l spr ing s sho uld n ot be used unt i l

.018 or .020 round s tee l wires a re in p lace .

• For the t rea tme nt s tages of space c losure and overje t

re duc t ion . Th e ma jo r too th mo ve m e n t s tha t oc c u r du r in g

these s tages of t rea tment require the r ig idi ty of a

rec tangular s ta inless s lee l wire , as opposed to the f lexibi l i ty

of a hea t-ac t iva ted wire .

In s umma ry , t he in t roduc t ion o f he a t -a c t iva te d w i re s ha s

prov ided a benefic ia l subs t i t u te for a nu m be r of t radi t io nal

s ta inless s tee l wires , an d can dramat ica l ly im pro ve th e

e f fi ci enc y o f o r th odo n t i c t r e a tme n t . Th i s s ubs t i tu t ion i s,

however , benefic ia l for in i t ia l tooth a l ignment procedures

only . The f lexibi l i ty of hea t-ac t iva ted wires can ac tua l ly be

detr imenta l in a number of o ther c l in ica l s i tua t ions , as

de s c r ibe d a bove . I t i s impor t a n t t ha t t he o r thodon t i s t

separ a tes the s i tua t ion s tha t require a rchwir e flexibi l ity from

those in which archwire r ig idi ty is needed.

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CLINICAL PROCEDURES IN LEVELING AND

ALIGNING - IMPROVING PATIENT

COMFORT AND ACCEPTANCE

At the s ta r t of t rea tment , every effort should be made to

e ns u re tha t d i s c omfor t a nd inc onve n ie nc e fo r pa t i e n t s a re

min imi zed . This wi l l norm al ly b e the ir f irst experience of

o r thodon t i c t r e a tme n t , a nd the re a re oppor tun i t i e s fo r the

o r thodon t i c t e a m to ma ke i t a good e xpe r i e nc e .

For many cases , the opening wires wi l l be .016

  I

  IANT, but

i f t he re a re ma jo r too th m a la l ign me n i s , a mu l t i s t r a n d .015

wire is preferable . Bends can be in t roduced in to .015

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mult is t rand wires , and these reduce the force appl ied to the

tee th a t the outse t (Case JN, p . 120 and Case DO, p . 208) .

The opening wires should not be t ied in t ight ly . Plas t ic

s l e e v ing s ho u ld be us e d lo ma k e l e ng thy s t re tc he s o f a rc hwi re

more c omfor t a b le .

The pa t i e n t s hou l d be g ive n p rop e r in s t ruc t ion on the us e

of wax and mild an a lges ics (Fig . 5 .3 5) . A go od su pply o f wax

s hou ld be p rov ide d , a nd i t s hou ld be ma de c le a r tha t m os t

discomfort wi l l d isappear a f te r the f i rs t few days .

Archwire ends should be careful ly turned in , and part icular

care is need ed wit h m ult is t ran d wires . Stee l and

  I

 IANT wire-

e nds s hou ld be f l a me d a nd que nc he d , t o a l low a c c u ra t e

turning in , and a lso ease of removal a t the f i rs t adjus tment

a ppo in tme n t . M ola r hooks s hou ld be tu rne d in (F ig . 5 .36A) .

Much can be made of se lec t ing colored modules a t the f i rs t

v is i t , for those pa t ients who l ike the idea of colors . There is a

c o l o r e d m o d u l e c u l t u r e a m o n g s o m e g r o u p s o f y o u n g s t e r s

(Fig . 5 .36H)! Se lf- l iga i ing brackets may be an inevi table

development in the future , but th is wi l l be a concern for

ma ny young e r pa t i e n t s , wh o look fo rwa rd to c ho os in g c o lo rs

at each visit .

F i g .

  5 .35 The pat ie n t shou ld be pro per ly ins t ruc ted on the use

of wax and mi ld ana lges ics .

F i g .

  5 .36A Mo la r hooks shou ld be tu r ned in .

F i g .

  5 .36B Many younge r pa t ien ts look fo rw a rd to choos ing

co loured modules a t each v is i t .

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I t i s correct to have a sen i or ass is tan t m ak e a fo l low -up

phone cal l a few days af ter p lacement o f the in i t ia l app l iances

(Fig . 5 .37) . Th is wi l l show that the p ract ice i s concerned to

kno w th at a l l is go i ng wel l , and i t i s a cha nce to o ffer adv ice

an d en co u rag emen t . Du r i n g t h i s ca l l , t h e p a t i en t o r p a ren t

wi l l o f t en r a i se mi n o r q u er i e s , wh i ch a r e i mp o r t an t t o t h em,

a l t h o u g h t h ey ' d i d n ' t wan t t o b o t h e r t h e d o c t o r ' .

As level ing and al ignment p rogresses , there wi l l be a swi tch

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F i g .

  5 . 3 7

  A f o l l ow -up pho ne c a ll s hou ld be m a de 5 -7 days

a f te r p lac em ent o f t he i n i t i a l app l i anc e .

REFERENCES

1 Mc La ugh l i n R P, Benn e t t J C 1999 An ana l ys i s o f o r t ho don t i c t o o t h

mo v em en t - t h e VTO. R ev is t a Es pana Or t od on t i c a 29 (2 ) : 10 -29

2 Mc La ugh l i n R P, Benne t t J C 1989 The t rans i t i on f r om s t anda rd

edgew is e t o p rea d jus t ed app l i anc e s y s t ems. J ou rna l o f C l i n ic a l

Or t hodon t i c s 23 : 142 -153

3 Ro binson S N   1989 An ev alua t ion of the changes in lower inc isor

pos i t i on du r i ng t he i n i t i a l s t ages o f c li n i c a l t r e a t m en t us ing a

p read jus t ed edg ew is e app l i anc e . U n i v e rs i t y o f Lo ndon MSc t hesi s

in to recta ngular H AN T wires . Th is can typ ical ly fo l low d i rect ly

f rom t h e .0 1 6 ro u n d HAN T in ma n y cases . T h e r ec t an g u l a r

I IANT wires are mo st usefu l and pa t ien t - f r iend ly , and the

swi t ch is t h e re fo re se l d o m ac co m p an i ed b y d i sco mfo r t . An y

b rack e t s wh i ch a r e wro n g l y p o s i t i o n ed sh o u l d b e r ep o s i l i o n ed

at the rectangular I IANT wire s tage, o r ear l ier .

Al t h o u g h t h e re h av e b een man y t ech n i ca l ad v an ces i n

o r t h o d o n t i c s , t h e re is a co n t i n u i n g n eed t o en su re g o o d

p a t i en t co o p era t i o n , i n o rd e r t o r each t r ea t men t g o a l s . Care

an d co n s i d e ra t i o n f ro m t h e o u t se t w i ll p ro v i d e a so u n d b as i s

for t h e t r ea t me n t r e l a t i o n sh i p . T h i s sh o u l d l ead o n t o b e t t e r

co o p era t i o n i n man y cases .

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CASE LB

A female p atient, 11.5 years old, w ith ne ar average MM

angle of 29°, slight Class III skeletal hases (ANB 1°) and a

deep bi le. Lower incisors were retrocl ined and crowded.

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F i g .  5 .38

All permanent teeth were developing, and there was a

possible supernumerary tooth in (he upper right third molar

region. The patient was informed that surgical uncovering of

the upper canine crowns might be needed during treatment.

F i g .

  5 .41

F i g .  5 .4 4

It was planned lo treat the case without extractions. .Mid-sized

brackets were placed wiih a .014 sectional steel upper wire,

and a .016 lower round HANT wire lo comm ence to oth

movements. The patient was asked to wear a sleeping

combination headgear. An upper acrylic removable bite plate

was supplied for full-time wear.

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F i g .

  5 .47

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t .B .

  Beginn ing

11.5 years

5/10/96

SN A

 

7 8

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P o - N

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1

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2 7

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F i g .  5.39

F i g .  5.40

F i g .

  5.42

F i g .

  5.43

F i g .

  5.45

F i g .

  5.46

F ig .  5.48

F i g .  5.49

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After 3 months of t rea tment , a .016 lower s tee l round wire is

in p lace , wi th coi l spr ings to recrea te space for lower canines ,

and proc l ine and a l ign lower inc isors . Brackets adjacent to the

springs are t ied to prevent ro ta t ions .

F ig .

  5 .50

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A sequ enc e of s l ides of the r ight s ide of the t rea tm ent a f te r 10

m o n t h s , 1 8 m o n t h s , a n d 2 1 m o n t h s , s h o w i n g c r e a t i o n o f

upp e r c a n ine s pa c e a nd the n bo nd ing o f a bu t ton a f te r

unc ove r ing . Dur ing t r e a tme n t , l owe r r igh t c e n t ra l a nd bo th

uppe r f i r s t p re mola r b ra c ke t s we re re pos i l ione d .

Fig. 5 .53

Normal .019/ .025 rec tangular s tee l wires in p lace af te r 22

mon ths o f t r e a tme n t . The pa t i e n t wa s a s ke d to we a r l i gh t

Class II e las t ics a t th is s tage . Some lower a rch enamel

redu ct ion w as carr ied out .

Fig. 5 .56

The re c omme nde d s e t t l i ng p ro toc o l wa s fo l lowe d wi th a

sec t ional upp er .014 wire and a .01 6 11 ANT lower wire .

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116

F i g .

  5 .59

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F i g .

  5 .52

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F i g .

  5 .51

F ig .

  5 .54

:

  " ^

:

F i g .

  5 .55

MR v .

" 9

F ig .

  5 .57

F i g .

  5 .58

Fig. 5.60

F i g .

  5 .61

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F i g .

  5 .63

F i g .

  5 .6 4

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Fig. 5 .66

F i g .

  5.67

L.B. Final

15.1 years

1/25/00

F i g .  5 .69

P a l a t a l P l a n e &

P a l a t e C u r v a t u r e

L.B.Begin

! f ) 3 l !

Fig.

  5.72

S N A

S N B

A N B

A-N F H

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W I T S

G o G n S N

F M

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1 t o A -Po

1 t o A -Po

t o M a x P l a n e

t o M a n d P l a n e

7 7 °

7 6 °

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3 9 °

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32 °

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114 °

88 "

M a n d .  S y m p h a s i s

& M a n d . P l a n e

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Fig .  5.73

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CASE JN

A ma le pa t i e n t , a ge d 13 .6 ye a r s a t t he s t a r t o f t r e a tm e n t ,

w i th M M a ng le 31 ° a nd C la s s I de n ta l ba s e s .

Fig. 5 .74

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De nta l ly , t he re wa s a n te r io r a nd pos te r io r c rowding , w i th

large th i rd molars developing. Arch form was assessed as

ovo id . I t was fel t tha t extrac t ion of four pre mo lar s wo uld be

required in order to achieve a sa t is fac tory and s table resul t in

this case . A dec is io n was m ad e to extrac t the f i rs t prem ola rs ;

a l though the s e c ond p re mola r s we re s l igh t ly s ma l l , t he y we re

c ons i s t e n t ly s o a nd the re fo re good upp e r a nd lowe r too th f i t

c ou ld b e a n t i c ipa te d a t t he e nd o f t r e a tm e n t .

Fig. 5.77

Fig . 5 .80

The t re a tme n t wa s ma na ge d a s a ma x imum a nc hora ge c a s e ,

a nd s t a nda rd m e ta l b ra c ke t s we re us e d fo r op t im a l c o n t ro l .

La c e ba c ks a nd be ndba c ks we re us e d in a l l fou r qua dra n t s ,

wi th a lower l ingual a rch and an upper pa la ta l bar to res t r ic t

m o l a r m o v e m e n t d u r i n g t o o t h a l i g n m e n t . U p p e r a r c h w i r e

wa s .016 HANT. Lowe r a rc hwi re wa s .015 mul l i s l r a nd , w i th

offse t ben ds for the buccal ly placed low er can ine s . Th e up per

lef t canine bracket was lassoed with a module .

Fig. 5 .83

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A N

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S N B

A N B

F H

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F i g .

  5 .78

Fig. 5 .79

F i g .

  5 .81

F i g .  5 .82

F ig .

  5 .84

F i g .

  5 .85

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Occlusa l v iews a t the s ta r t of t rea tment show the lower l ingual

arch and upper pa la ta l bar , wi th lacebacks in p lace to control

and then re t rac t the canines .

Sequent ia l v iews of the r ight s ide of the case 2 months , 4

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months , a nd 6 mon ths in to t r e a tme n t . In the uppe r a rc h , t he

ini t ia l .016 HAN T wire was fol lowed by a rec tangular HANT

wire and then a .01 9/ . 02 5 rec tangula r s tee l wire . In the lower

arch, a rec tan gular I IAN T wire was placed af te r 4 m on th s , a nd

c on t inue d in u s e a t 6 mon ths . The lowe r r igh t c a n ine wa s

re t ra c t e d w i th l a c e ba c ks , a nd the uppe r c a n ine s imu l t a ne ous ly

mov e d d i s t a l ly (p . 101) . Th i s p rov ide d a s ma l l a m ou n t o f

a dd i t iona l a nc hora ge du r ing too th l e ve l ing a nd a l ign ing .

After 9 months of t rea tment , upper and lower s tee l

rec tangular wires a re in p lace and space c losure is cont inuing.

Occlusa l v iew a t 9 months . Ful l upper space c losure wil l not

be pos s ib l e un t i l more pa la t a l roo t t o rque o f the uppe r

inc isors has been achieved (p . 284) . During tooth leve l ing

and a l ig ning, i t i s con ven ient lo have a checkl is t w hich

inc lude s l a c e ba c ks , a nc hora ge s uppor t , a rc hwi re s i z e a nd

e nga ge me n t , be ndba c ks , a nd p ro te c t ion . 'P ro te c t ion ' r e fe r s to

protec t ion of the appl iance and archwires in the ear ly s tages

of t rea tment , as wel l as protec t ion of the pa t ient 's sof t t i s sues

from sharp aspec ts of the appl iance , such as d is ta l ends of the

a rc hwi re wh ic h ha ve no t be e n p rope r ly tu rne d in .

F i g .

  5 .89

122

F i g .

  5 .95

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F i g .

  5 .88

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F ig .

  5 .90

F i g .

  5 .91

F ig .

  5 .93

F i g .

  5 .9 4

LEVELING AND AL IGNING

check l i s t

• Lacebacks

• Anch orage suppo rt

• Archw ire s ize and engagem ent

• Bendbacks

• Protect ion

F ig .

  5.96

F i g .

  5 .97

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After 1 year of t rea tm ent , low er seco nd m olar s were b an de d

after sui table separa t ion and upper f i rs t molars were

re ba n de d . R e c ta ngu la r uppe r a nd lowe r HANT wire s we re

placed with lacebacks to prevent extrac t ion spaces reopening

during re- leve l ing and a l igning.

F ig .

  5 .98

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Oc c lus a l v i e ws 12 mon ths in to t r e a tme n t s how the ne e d lo

correc t the pos i t ion of the lower le f t second molar .

R e c ta ngu la r  I IANT wires a re very effec tive in achiev ing too th

movements of th is type in th is region. They give good control

and do not d is tor t in response to mas t ica tory forces .

The c a s e a f t e r 16 mon ths o f t r e a tme n t . Norma l uppe r a nd

lower rec tangular s tee l wires a re in p lace and upper inc isor

to rque i s improv ing . Uppe r a n te r io r t e e th we re t i e d w i th .010

wire l iga tures to obta in ful l express ion of the bracket sys tem

(p .  20) .

After 19 mon ths o f t r e a tm e n t , s e tt l i ng wa s c om me nc e d us ing

.014 round wi re s in bo th a rc he s a nd up -a nd- dow n e l a s t i cs .

The pa t ient was checked a t 2-weekly in terva ls for

a pprox ima te ly 6 we e ks .

F i g .

  5 .1 0 1

F i g .

  5 .1 0 4

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F i g .

  5 .107

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F ig .

  5 .99

F i g .

  5 .100

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F ig .

  5 .102

F ig .

  5 .105

F ig .

  5 .108

F i g .

  5 .103

F i g .

  5 .106

F i g .

  5 .109

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The case after removal of appliances. Active treatment time

was 22 months and conventional retainers were used, with

the lower bonded retainer extended onto the lower second

premolars to prevent lower extraction spaces reopening.

F i g .

  5 .110

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The panoial radiograph confirms that there is adequate space

for the developing third molars, and that the upper canine

root positions are favorable, relative to the second prem olar

roots, owing to the 8° of tip in the canine brackets.

F i g .

  5 .113

During the treatment period, considerable Class

 111

  growth

occurred, with a final ANB angle of

  1

 °. Th e facial profile

shows pleasing balance and harmony.

F i g .

  5 .116

126

F ig .

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SN a t S

J . N .  B e g i n

J . N .

  F i n a l

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F i g .  5 .1 1 1

F i g .

  5 .112

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F i g .

  5 .1 1 4

F i g .

  5 .1 1 5

J.N.Finn

15.7 years

11M/98

F i g .  5 .1 1 7

P a l a t a l P l a n e &

P a l a t e C u r v a t u r e

J . N .

  B e g i n

F i g .  5 .120

SNA   79 •

S N B 7 8  °

A N B 1  *

A-N F H -2 m m

Po-N F H 0 m m

W I T S - 2 m m

GoGn SN 33 °

FM / 25 °

M M 2 8 

1 t o A -Po 4 m m

1 t o A -Po 2 . 5 m m

t o M a x P la n e 1 1 3 °

1 t o

  M a u d

  P l a n e

  97 '

M a n d . S y m p h a s i s

& M a n d . P l a n e

J . N .  B e g i n

F i g .

  5 .1 2 1

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CHAPTER

Arch leve ling and o v erb i te con t ro l

Introduction 131

Extraction treatment  138

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The develop me nt of deep overbite 131

The tooth mo vem ents of bite op enin g 132

Eru ption /extru sion of poste rior teeth 132

Dista l t ippin g of poste r ior tee th 133

Proc lination of incisors 133

Intrusio n of ante rior teeth 133

Light forces du rin g leveling an d align ing 139

Light forces du rin g space closure 141

The development of anterior open bile

  142

Early ma nage me nt of ope n b i tes 143

Management of anter ior open b i te during fu l l

or th odo ntic t rea tmen t 144

C a s e  MP  A maximu m anchorage deep bite  case

with extraction of four first prem olars 146

Case CW   A deep bile non-extraction

treatment 152

Non-extraction treatment

  134

Initial archw ire pla cem ent 134

Th e bite-pla te effect 134

Crea ting the bite-plate effect 135

The impo rtance of second molars 136

Torque issues 136

Bite-op ening curves 137

An tero-po sterior issues and elastics 138

Spacing in non-e xtractio n cases 138

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THE TOOTH MOVE MENTS OF BITE

OPENING

The correc t ion of de ep overb i te involves revers ing the abo ve

proc e s s , a nd i s a c c om pl i s he d by va r ious too th mo ve m e n t s ,

inc luding the fol lowing:

• Eru pt ion /extru s ion of pos te r ior tee th (Fig . 6 .5)

• Dis ta l t ipp ing of pos te r ior tee th (Tig . 6 .6)

• I ' roc l in a t ion of inc isors (Fig . 6 .7)

• In t ru s ion of inc isors (Fig . 6 .8)

• A c om bin a t io n o f two o r mo re o f the a bov e too th

m o v e m e n t s .

Erupt ion /ex t rus ion o f pos ter io r tee th

Th e e rup t ion o f pos t e r io r te e th i s a no rm a l ve r ti c al mo la r

change in a growing individual . I t i s a s table process tha t

a c c o mp a n ie s ve rt i ca l fa ci al de v e lop me n t .

Th e no r ma l e rup t ion o f pos t e r io r t e e th i s a c on t r ibu t ing

fa c to r in a c h ie v ing b i t e ope n ing in de e p -b i l e pa t i e n t s

(Fig 6 .5) . Th e increase in vert ica l fac ia l he ig ht in g row ing

pa t i e n t s a l s o a c c ommoda te s the e x t rus ion o f pos t e r io r t e e th

tha t c a n oc c u r du r ing o r thodon t i c t r e a tme n t , whe n l e ve l ing o f

the curve of Spec and us ing in ter-maxi l la ry e las t ics (Class II ,

(Mass III, and vertical).

However, the extrus ion of pos ter ior tee th in adul ts wi th

a ve ra ge to low ma nd ibu la r p l a ne a ng le s i s no t a s t a b le

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proc e s s . The mu s c u la tu re ge ne ra l ly re s i s ts t h i s e x t rus ion a nd

by the end of t rea tment , or short ly a f te r , the molars re turn to

the i r o r ig ina l ve r t i c a l pos i t ion a nd the ma nd ibu la r p l a ne

re turns to i ts or ig ina l pos i t ion. This may become a source of

pos t -o r thodon t i c r e l a ps e a nd re tu rn o f the de e p ove rb i t e . In

h igh -a ng le a du l t pa t i e n t s w i th we a ke r mus c u la tu re ,

o r thodon t i c e x t rus ion o f pos i e r io r t e e th ma y re ma in s t a b le a t

the e nd o f t r e a tme n t , w i th pe r ma ne n t ope n ing o f the

ma nd ibu la r p l a ne . Thi s i s unde s i ra b le in mos t h igh -a n g le

cases.

F i g .  6 .5 E rup t i on /ex t r us ion o f pos te r i o r t ee t h .

132

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D i s ta l t i p p i n g o f p o s te r i o r t e e th

This is normal ly a s table process in the growing pa t ient , as i t

i s acc om mo dat ed by the increase in vert ica l fac ial he igh t .

However, in mos t average- to low-angle adul t cases , d is ta l

l ipping of pos ter ior tee th is not s table , because i t wi l l be

followed by int rus ion o f thes e teeth to the orig inal vertical

d ime ns ion . Th i s ma y no t oc c u r du r ing o r thodon t i c t r e a tme n t

but wi l l normal ly fol low short ly a f te r , and can be a source of

pos t -o r thodon t i c r e l a ps e o f the de e p b i t e . In the a du l t h igh -

angle pa t ient , the dis ta l t ipping of pos ter ior tee th may lead to

s o m e p e r m a n e n t o p e n i n g o f t h e m a n d i b u l a r p l a n e a n d i s t o

be a vo ide d . Som e t im e s the e qu i l ib ra t ion o f pos t e r io r t e e th

afte r d is ta l l ipping is benefic ia l in these high-angle adul t cases

(Fig. 6.6).

F i g .  6 .6 D is ta l t i pp ing o f pos te r i o r t ee th .

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O

Proc l ina t ion o f inc isors

Nume rous de e p -b i t e c a s e s p re s e n t w i th re t rod ine d inc i s o rs ,

and proc l ina t ion of these tee th conlr ibu tes to b i te op en in g in

the anter ior a rea . In the lower a rch, th is genera l ly cons is ts of

lower inc isor c rowns be ing proc l ined. In the upper a rch, a

c om bina t ion o f c row n p roc l ina t ion a nd roo t t o rque c on t ro l

normal ly occurs , wi th roots moving dis ta l ly in the bone

(Fig. 6.7).

I n t r u s i o n o f a n te r i o r t e e th

33

o

F i g .  6 . 7 Proc l inat io n of inc isors .

In the majori ty of t rea tments for growing pa t ients , in t rus ion

of  anter ior tee th is normal ly not required. As the face grows

vert ica l ly , prevent ing or even res t r ic t ing the normal e rupt ion

of these anter ior tee th wil l essent ia l ly a l low the bi le to 'grow

ope n ' a s pos t e r io r e rup t ion , e x t rus ion , a nd /o r d i s i a l t i pp ing

occur.

This is not t rue in adul t cases , where the muscula ture

resists  the s e  pos te r io r c ha n ge s . The re fo re , b i t e ope n in g in

a du l t s mus t be b rough t a bou t by the p roc l ina t ion o f inc i s o rs

and /or the in t rus ion of ihese tee th . Th e in t ru s ion of ant er io r

tee lh in these adul t cases can be brought about wi th ful l a rch

trea tment , b ut the process occurs s lowly. Therefore , the use of

supplementa l in t rus ion arches , as advocated by Ricket ts or

Burs tone , may ass is t the inc isor in t rus ion process which is

required for these adul t pa t ients (Fig . 6 .8) .

F i g .  6 .8 I n t r us ion o f an te r i o r t ee th .

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a\ NON-EXTRACTION TREATMENT

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Non-extraction treatment generally favors bite opening. This

is because distal tipping of posterior teeth and proclination of

incisors normally occurs in these cases. There are a nu mb er of

mechanical factors that lead to arch leveling and control of

the deep overbite:

In i t ia l archwire p lacement

When flat archwires are placed into dental arches with curves

of Spee, the archwires attempt to return to their original shap e

and this starts the bite-opening process. Also, expression of

the tip in the brackets begins the bite-ope ning process.

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The bite-plate effect

Introducing the bile-plate effect (Fig. 6.9) in deep-bite cases is

helpful in the bile-opening process in three ways:

1. It allows for early placement of brackets on lower incisors,

which begins their movement.

2.  Anterior bite plates can produce an intrusive force on lower

incisors which limits any future extrusion of these teeth.

3 . Anterior bite plates allow for the eruption, extrusion,

and/or uprighting of posterior teeth.

F i g .

  6 .9 T he b i te -p la te e f fec t is he lp fu l i n the b i te -o pen in g

process.

134

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Creat ing the bite-plate effect

There are four methods of c rea t ing the bi te -pla te e ffec t :

1.

 App l iances can be placed on th e uppe r a rch only , w hich

al lows for proc l ina t ion of the upper inc isors (Fig . 6 .10A).

This frees the lower inc isors for p lacement of brackets . This

tech niq ue is he lpful in h igh-a ngle cases , beca use p os ter i or

e x t rus ion i s min imiz e d .

2.  Acrylic rem ova ble ante r ior b i te p la tes can be p laced

(Fig. 6.1 OB). This is par t icular ly he lpful in low-angle deep -

bi te cases , because i t encourages dis ta l l ipping, e rupt ion,

a nd e x t rus ion o f mo la r s . The d i s a dva n ta ge o f the s e

removable appl iances is tha t they are not a lways worn by

the pa t i e n t . A l s o , t oo th move me n t s l e a d  to  improper f i t of

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these appl iances a f te r a re la t ive ly short per iod of t ime.

3.  An adequate subs t i tu te for a removable bi te p la te in low-

a ng le de e p -b i t e c a s e s i s t he p l a c e me n t o f d i re c t bond ing

materia l on the pa la ta l surface of the upper inc isors

(Fig . 6 .11) . Colored adhes ives such as Bandlock

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and can be eas i ly removed from the tooth surfaces a f te r

b i t e ope n ing .

4.

  In average- to h igh-angle cases , the placement of s imilar

colored adhes ives on the occ lusa l surface of the f i rs t molars

is  helpful in b i te op en ing (Fig . 6 .1 2) . This adhes iv e can b e

progress ive ly rem oved as the bi te open s . W hen f irst mo lars

have res tora t ions , i t may be diff icul t to bond to the

occlusa l surface of these tee th . Therefo re , th e seco nd

premolars or second molars can be used in such cases .

F i g .

  6 . 1 0 A

  App l iances may be p laced on th e upper arch on ly .

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F i g .

  6 .1 0 B

  Acry l ic rem ovab le b i te p la te .

F ig .

  6 .11  D i rec t bond ing ma ter ia l on th e pa la ta l aspect o f

upper incisors.

F i g .

  6 .1 2

  B lue co lore d d i rec t bon d in g mate r ia l on the occ lusa l

surfaces of lower f irst molars.

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The impor tance o f second mo la rs

In average- to low-angle deep-bile cases, the earliest possible

banding or bonding of the second molars, especially the

lower second molars, is most beneficial in bite opening.

Inclusion of the second molars provides an excellent lever

arm for eruption or extrusion of the premolars and first

molars, and assists in incisor intrusion (Fig. 6.13). In

numerous cases, the authors have observed tha t complete bi le

opening and leveling of the curve of Spee in the lower arch is

extremely difficult if the lower second molars are not included

(Fig. 6.14).

Torque issues

During early leveling procedures with round wires, torque

changes occur, especially amon g a nterior teeth. These actually

begin to produce favorable torque changes in the case, before

placement of rectangular wires. The flexibility of 1IANT wires

allows for early placement. This allows earlier torq ue control

than was possible when only steel wires were available.

Rectangular steel .019/.025 wires typically follow the

rectangular HANT wires (p. 111). These rectangular steel wires

are normally placed flat, without introducing torquing bends

or any archwire curves. After they have been in place for at

least 6 weeks, torque bends and archwire curves can be added

to rectangular steel wires as necessary. Up to 20° of palatal

root torque can be introduced into the upper wire in the

incisor area, and 10° to 15° of labial root torque can be

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There is a tendency to believe that torque is introduced into

the dentition by rectangular wires only, but this is not so.

introduced into the incisor area of the lower wire (Fig. 6.15).

These torque changes contribute to the bite-opening process.

F i g .  6 .13

  Leve l ing o f the curve o f Spee in th e lowe r arch is d i f f icu l t i f the lowe r second molars are not inc lu ded . Inc lus ion o f t he

second molars ass is ts in inc isor in t rus ion and correc t ion o f the overb i te , together w i th comple te leve l ing o f the curve o f Spee.

- * -

136

F i g .

  6 .1 4

  Lower second molars are not in clud ed in this case,

and compl e te b i te open ing and leve l ing o f the curve o f Spee

have not occurred.

F i g .

  6 . 1 5

  Rectangu lar s tee l w i res are norm al ly p laced f la t .

A f te r the y have been in p lace fo r a t leas t 6 weeks, upper

pa la ta l roo t to rque and low e r lab ia l roo t to rque can be

in t roduc ed in to the w i res , as show n above .

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Bite-opening curves

The authors prefer not to p lace bi te -opening curves in round

wires or to have such curves bui l t in to rec tang ular hea t-

activated wires. The y accept th e fact tha t such wires do no t

comple te the leve l ing of the a rches and the bi te -opening

process. In the great majority of cases after rectangular

stainless steel wires have been in place for 6 weeks, the arches

are norm al ly leve l and a deq ua te bi te op en ing has be en

achieved. I f th is is not so , then bi te -opening curves can be

placed into the rectangular steel wires.

Placing  a  b i t e -ope n ing c u rve in the uppe r a rc hwi re

increases palatal root torque to the upper incisors. This is

beneficial in the majority of cases and it is usually

unne c e s s a ry to a dd a ny a dd i t iona l t o rque be nds to th i s uppe r

wi re ,  bu t i s s ome t ime s ne e de d (F ig . 7 .185 , p . 210 ) .

When bi te -opening or reverse curve is p laced in the lower

rec tangular s tee l wire , the resul t i s proc l ina t ion of lower

inc isors . This is genera l ly not indica ted. Therefore , before

p la c e me n t o f a b i t e -ope n ing c u rve in the lowe r w i re ,

approximate ly 10° to 15° of labia l root torque can be added.

After th is , b i te -opening curves can be placed and the ne t e ffec t

wil l be a re t roc l in ing and in t rus ive force on the lower inc isors

(Fig . 6 .16) .

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  6 .16  I f necessary , b i te -op en ing curves can be p laced in up per an d lowe r rec ta ngu lar s tee l w i re s af te r the w i res have been in

p lace for 1 or 2 mo nth s . The low er w i r e needs to be f la t (no torq ue ) in th e inc isa l reg ion to prev ent p roc l ina t ion o f low er inc isors.

Bo th a r c hw i res a re no rm a l l y f l a t ( no t o rqu e) i n t he m o la r r eg ions , un les s t he re is a need fo r m o la r t o r qu e c hanges . App rox im a te l y

3-4 mm o f reverse curve is ap pro pr ia te i f the second m olars are inc lud ed. I f th e second molars are no t inc lu ded , s l igh t ly less reverse

curve is norm al ly ap pro pr ia te.

F i g .

  6 .17

F i g .  6 .1 8

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Antero-poster ior issues and elast ics

Class II or Class III inter-maxillary elastics are often used to

correct antero-posterior problems, and it is recommended that

rectangular stainless steel wires should be in place when they

are used. Inter-maxillary elastics can contribute to the bite-

opening effect by assisting in the extrusion of molars as the

A/P problem is corrected (Tig. 6.19). They are beneficial in the

treatment of most growing p atients. If possible they should be

avoided in most non-growing and adult high-angle cases.

Spacing in non-extract ion cases

Non-extraction cases normally do not show significant

amounts of spacing. When spaces occur, they can generally be

EXTRACTION TREATMENT

Most of the mechanical treatment procedures described for

deep-bite non-extraction cases also apply to deep-bile

extraction cases. These include the effects of arc hw ire

deflection, tip in the brackets, the use of bite-plate effect, the

banding of second molars, the torquing effect of rectangular

wires, the effect of bite-opening curves in rectangular wires,

and the effects of inter-maxillary elastics.

I

  lowever, there are two other important factors in

extraction deep-bite cases:

• With extraction cases, lower incisors are norm ally

maintained in their position or brought to a more

retroclined position. This makes the bite opening more

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closed without difficulty with the use of tiebacks as described

in the space closure chapter (p. 254) . This can be

accomplished after leveling and bite-opening procedures.

Space closure should not be attempted until full bile

opening and leveling has been achieved.

difficult.

• If space closure is attempted before proper arch leveling

and overbite control, it will lead to bite deepening.

O ne of the great advantages of the preadjusted applian ce

system is the ability to use sliding mechanics. For this reason,

the majority of orthodontists are using sliding mechanics as

opposed to closing loop arches. In order to effectively slide a

rectangular wire through posterior bracket slots, it is necessarv

for these segments to be free of friction. It is therefore

important to complete arch leveling and overbite control

before starting space closure. This will minim ize friction.

When arch wires are in a deflective state due to incomplete

leveling and bite opening, they cannot effectively slide

through the posterior bracket slots during space closure,

because of the friction.

F i g .  6 .19 C lass I I in ter -m ax i l lary e las t ics can co nt r ibu te to the

b i t e -open ing e f f ec t .

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Light forces dur ing level ing and a l igning

If premolars are extracted in deep-bite cases, it is normally to

reduce anterior protrusion or eliminate anterior crowding, or

a combina tion of the two. If there is anterior protrusion

without crowding, it is possible to retract the anterior

segments en masse. Alternatively, the canines can be retracted

alone, followed by retraction of the incisors. If the latter

decision is made, extreme care must be taken not to tip the

cupids distally because this results in extrusion of the incisors

and further bite deepening (Fig. 6.20). For this reason, the

authors prefer to carry out en masse retraction of the anterior

six teeth with a rectangular steel wire after arch leveling and

overbite control.

In cases with anterior crowding, it is necessary to retract

canines at least until there is enough space for proper incisor

attempt to maintain a Class I canine relationship. Therefore,

in certain cases, the canines may be retracted a greater

distance to maintain this Class I position. This may result in

some spacing mesial to the canines (Case |N, p. 123). It has

been observed in many cases that the contact of the lower

canine against the uppe r canine serves to distalize the uppe r

canine. This addition al source of anchorag e is helpful in the

overall management of the upper anterior segment. The upper

arch can then be retracted en masse using rectangular stainless

steel wires.

There is a tendency for incisors and canines to tip mesially

after placement of the opening archwires, due to the built-in

tip features of the pread justed applian ce system. C ani ne -

lacebacks (p. 15) should be used to resist this mesial lipping

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alignment. In the lower arch, this is the authors' preferred

treatment meth od. After crowding has been eliminated in the

lower incisor region and the case has been leveled to the

rectangular steel wire stage, then en masse movement is

carried out. In the upper arch, it is not only important (o

retract canines until crowding is eliminated, but also to

of the canines and to retract these teeth effectively without

distal tipping. Llastic forces should be avoided, because they

can result in excessive distal tipping of the canines. This can

lead to posterior bile opening, and the overall reaction has

been called the 'roller coaster' effect (Fig. 6.20), which

increases overall treatment time.

F i g .  6 .20 Canine e las t ic re t ra c t io n forces shou ld be avo ided

because they can resul t in d is ta l t ipp ing of the canines , leading

to the ' ro l ler coas ter ' e f fec t . Th is inc reases overa l l t reatment

t im e .

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Lacebacks (p . 100) in i t ia l ly compress the periodonta l

l igament space on the dis ta l aspec t of the canine , leading to

s l ight t ipping . This is fo l lowed b y ad eq ua te t im e for

Liprighting, in response to the leveling effect of the archwire.

This uprighl ing occurs wi th a laceback, but i t i s not seen i f

e las t ic cha ins a re used, because they give a cont inuous force

whic h doe s no t a l low t ime fo r r e bound to oc c u r .

The discuss ion thus fa r has assumed a favorable in i t ia l

pos i t ion o f the c a n ine s w i th the c rowns a t s l i gh t o r mode ra te

a n te r io r inc l ina t ion . Howe ve r , i f c a n ine s s how unfa vora b le

angula t ion a t the s ta r t of t rea tment (Fig . 6 .21) , much grea ter

care is needed to ensure good overbi te control . Figure 6 .22

s how s ho w p re a d jus ie d b ra c ke t s on un fa vo ra b ly a n g le d

c a n in e s c a n c a us e unw a n te d e x t rus ion o f inc i so rs a f t e r t he

provides grea ter s tabi l i ty to the a rch form and minimizes

d i s t a l t i pp ing o f the c a n ine s . Howe ve r , whe n c a n ine s a re

unfav orably ang led, it ma y be benefic ia l to avoid br ack et ing

the inc isors unt i l the canine roots have been re t rac ted,

p rov id ing more fa vo ra b le a ngu la t ion o f the c a n ine s lo t s . Th i s

me thod min imiz e s the ine v i t a b le t e nde nc y fo r b i t e de e pe n ing

in such cases . An a l te rna t iv e techn iqu e involves plac in g a

bend in the a rchwire , mes ia l to the canines , to prevent a s l ight

in t rus ive force on the inc isors whi le the canine roots a re be ing

moved dis ta l ly .

In summary, i t i s c lear tha t there a re many fac tors which

can lead to bi te deepening during the in i t ia l leve l ing s tage .

Effec t ive overbi te control requires the use of l ight forces , wi th

m i n i m a l a c t i v a t i o n a n d a d e q u a t e r e b o u n d t i m e . L a c e b a c k s

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i n i t i a l a rc hwi re s ha ve be e n p la c e d . The a u tho rs no rma l ly

prefer to bracket the inc isors tha t a re in reasonably good

al ignment and inc lude them in the in i t ia l a rchwires . This

have proven to be the mos t e ffec t ive way of control l ing canine

pos i t ion a nd mo ve m e n t , a nd he n c e the ove rb i t e , in the s e

cases.

F i g .

  6 .2 1 Unfa vora b le d is ta l t ip p in g o f the lower can ines a t th e

s ta r t o f t rea tmen t . Grea te r ca re and t im e w i l l be requ i red to

ensu re good ove rb i te con t ro l .

+ 4

140

F i g .

  6 .22 Unfavo rab ly ang led can ines can cause unw ant ed ex t rus io n o f the inc isors a f te r

p lacement o f the in i t ia l a rchw ires .

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Light forces during space closure

It is important to use light force levels during the stage of

space closure. Heavy forces can cause the bite to deepen in

two ways:

• The canin es can tip into the extraction sites causing

archwire deflection and binding. The sliding m echanics

then become ineffective, and the overbite deepens.

• Excessive force overpowe rs the incisor torque contr ol of the

rectangular wire (Fig. 6.23), particularly in the upper arch,

causing distal tipping and b ite deepe ning.

A

  small amount of torque added to the upper archwire in

the incisor region, combined with lighter forces, is usually

effective in minimizing these two bite-deepening factors.

The authors have tried various force levels during space

closure and feel that a range of 150-200 gm is most effective.

This minimizes any tendency to unwanted bite deepening,

and allows for efficient sliding mechanics and space closure.

Active tiebacks (pp 256 & 257) are used to deliver a force of

this size.

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F i g .  6.23 Excessive forc e du r in g space c losure can cause dis tal

t i p p i n g a n d b i t e d e e p e n i n g .

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THE DEVELOPMENT OF ANTERIOR OPEN

BITE

An t e r i o r o p en b i t e can d ev e l o p as a r e sul t o f g en e t i c a n d / o r

en v i ro n m en t a l f ac to r s . E n v i ro n me n t a l f ac to r s i n c l u d e f i ng er

an d t h u m b h ab i t s (F i g. 6 .2 4 ) , t o n g u e p o s t u r i n g an d t h ru s t i n g

p ro b l ems , an d r esp i r a t o ry co n cern s r e l a t ed t o co n d i t i o n s su ch

as a l l erg i es , ad e n o i d s an d t o n s i l s , an d mo u t h b rea t h i n g .

Genet ic factors can con t r ibu te to an ter io r open b i le in the

fo l l o wi n g m an n e r . I f p a t i en t s sh o w an ex cess o f an t e r i o r

vertical facial growth relative to posterior vertical facial

g ro wt h , t h ey a r e mo re p ro n e t o an t e r i o r o p en b i t e . T h ese

'h i g h -an g l e ' cases f r eq u en t ly sh o w a s t eep m an d i b u l a r p l an e

angle an d a long lowe r facial heigh t . Such cases are referred to

as skeletal ope n b i tes , and a re mo st d i f ficu l t to t reat

o r t h o d o n t i ca l l y , b ecau se co r r ec t i o n n o rmal l y r eq u i r es

co n s i d e rab l e e ru p t i o n an d t o rq u i n g o f i n c i so r s .

On t h e o t h e r h an d , i f p a t i en t s h av e an av erag e o r sh o r t

lower facial heigh t (average- to low-angle cases) (F ig . 6 .25) ,

a l t h o u g h en v i r o n m en t a l f ac to r s may l ead t o an an t e r i o r o p en

bi le , they are usual ly much easier to t reat . El iminat ion of the

causat ive factors a l lows rap id b i te c losure, s ince s ign i f ican t

e ru p t i o n an d t o rq u i n g o f t h e i n c i so r s a r e n o t r eq u i r ed . S u ch

cases are referred to as den tal op en b i les and can be corr ected

wi th l i t t le d i f f icu l ty by el im ina t ing the en v i r on m en tal factors .

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F i g .  6 .24 Th is pa t i en t had an as y m m et r i c a l den ta l an te r i o r op en b i t e , w h ic h w as re la ted to r i gh t t hu m b s uc k ing ac t i v it y . An te r i o r

open b i t es o f t h i s t y pe a re o f t en no t d i f f i c u l t t o c o r rec t , p rov ided the d ig i t s uc k ing i s d i s c on t i nued .

142

F i g .  6 .25 The above case sho wed a near -average ve r t ica l

s k e le ta l pa t t e rn , and the den ta l open b i t e w as re la ted to t hu m b

s uc k ing .

  I t is norm al ly poss ib le to cor rec t an ter io r op en b i tes o f

t h i s t y pe , p rov ide d the t hu m b-s u c k ing ac t i v i t y is d i s c on t i nue d . I f

t he ope n b i t e i s r e la ted to t ong ue pos tu re , t he p rognos i s f o r

pe rm anen t c o r rec t i on is m ore do ub t fu l .

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Ear ly management of open b i tes

Pat ients w ho prese nt wi th anter io r op en bi tes ma y b enefi t

f rom a n e a rly pha s e o f tr e a tme n t . A nu m be r o f t r e a tm e n t

modal i t ies have been sugges ted for th is ear ly management .

The fol lowing poss ibi l i t ies can be cons idered, and are l is ted in

order of ease of appl ica t ion and t rea tment :

• Finger an d th um b appl iance s , whic h provide a barr ie r , can

be us e d to c o r re c t mi nor p rob le ms . The s e a pp l i a nc e s

normal ly extend forward from the upper f i rs t molars , but

are somet imes a t tached to the lower f i rs t molars .

• Pa la ta l expa ns ion in cases with narro w maxi l las . This

procedure provides space for e rupt ion and re t roc l ina t ion of

inc isors . I t a lso he lps to open the a i rway and encourage

na s a l b re a th ing , wh i l e p rov id ing more room fo r the

• High- pul l facebows and vert ica l chin cups , wh en wor n

faithfully, can limit the vertical eruption of the upper

molars and the upper and lower molars , respec t ive ly .

I lowever , coo pera t ion is a lways the l im it ing lac tor wi th

s uc h a pp l i a nc e s .

• R e mova l o f de c id uou s c a n ine s a nd s om e t im e s p re mola r s

in cases with s ignif icant c rowding and/or protrus ion a l lows

for the e rupt ion and re t roc l ina t ion of inc isors .

• Myo funct ion al therap y ma y benefi t mo re severe cases. It

s hou ld be no te d tha t a s ign if i c an t nu m be r o f ope n-b i t e

cases show improvement as the a i rway increases in s ize

dur ing o r thodon t i c s . The re fo re , on ly a fe w pa t i e n t s r e qu i re

this service.

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t ongue .

• Pa la ta l bars and l ingual a rches can be placed on the

mo lars . These ap pl ian ces serve to reduce the vert ica l

e rup t ion o f the mo la r s .

• Pos ter ior b i te p la tes can be placed on the up per or lower

pos ter ior tee th . However, i f these only pass ive ly rota te the

mandible open (espec ia l ly in h igh-angle cases) , the ir e ffec t

may be minimal , s ince l i t t le pressure seems to be exerted

on the de n t i t i on .

• I f ad en oid s and to ns i ls a re con tr ib ut in g fac tors to anter ior

open bi tes , the ir removal may a id in b i le c losure . Referra l

to an ear , nose and thro a t spec ia l is t is indica ted in such

cases .

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M a n a g e m e n t o f a n t e r i o r  open  b i t e

d u r i n g f u l l o r t h o d o n t i c t r e a t m e n t

S o me g enera l co n s i d e ra t i o n s for t h e man a g em en t o f an t e r i o r

o p en b i t e d u r i n g fu l l-b an d ed o r t h o d o n t i c t r ea t me n t a r e

included in th is sect ion . Whi le non-ex t ract ion t reatment i s

general ly p referred in o r thodont ics , some open-b i te cases may

benef i t f rom ex t ract ions , p r imar i ly to al low for erup t ion and

ret rocl inat ion of incisors . Some possib i l i t ies are as fo l lows:

• If t h e u p p e r an d l o wer a r ch es sh o w c ro w d i n g a n d / o r

pro t rusion , upper and lower b icusp id ex t ract ions can be

co n s i d e red .

• I f the lower arch does no t requ i re ex t ract ion for lower

incisor ret rocl inat ion , and the molars are more than

3- 4 mm Class II , ex t ract ion of upper b ic usp id s on l y can be

g ing ival than norm al (p . 65) . Th is s im ple p roce dure helps

t o ach i ev e b i t e c l o su re a s t r ea t men t p ro cee d s .

• It i s n o t r eco mm en d ed t h a t s eco n d mo l a r s b e b an d ed i n

the ear ly and middle s tages o f t reatment o f open-b i te cases ,

becau se th is can lead to the ex t rusion of the p rem ola rs a nd

f irst mola rs , and fur ther b i le ope n in g . I f seco nd mo lars

n eed t o b e b an d ed fo r i mp ro v ed p o s i t i o n i n g o r fo r t o rq u e

control later in treatment, i t is beneficial to leave curve of

S p ec i n t h e p o s t e r i o r a sp ec t o f t h e l o wer a r ch an d t o s t ep

the archwire up to the second molars in the upper arch .

This wi l l min imize ex t rusion of f i rs t molars and b icusp ids .

• Ap p l i an ces d esc r i b ed ab o v e su ch as t o n g u e ap p l i an ces ,

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considered (Case LJ, p . 18 4) . Th is wi l l a l low for the

ret ract ion and ret rocl inat ion of upper incisors .

• I f the lower arch does no t requ i re ex t ract ion for incisor

ret rocl inat ion , and the molars are less than 3 mm Class I I ,

ex t ract ion of upper b icusp ids i s a concern . I t i s most

d i f f i cu l t t o mo v e u p p er mo l a r s fo rward 4 -7 mm an d k eep

thei r roo ts in an upr igh t pos i t ion . This i s requ i re d for

p ro p er C l ass I I mo l a r o cc l u s i o n . Up p er seco n d mo l a r

ex t ract ion can be cons idere d in such cases , i f goo d th i rd

molars are p resen t . Th is a l lows for easy d is ta l izat ion of f i rs t

mo l a r s , w i t h o u t o p en i n g o f t h e man d i b u l a r p l an e .

• Dur in g bracket p lac em ent o f ope n-b i te cases , the upp er

and lower an ter io r b rackets can be p laced 0 .5 mm more

palatal bars , l ingual arches , poster io r b i te p lates , h igh-pu l l

facebows, and ver t ical ch in cups can be helpfu l in these

cases . Also , tonsi l and adenoid evaluat ion , as wel l as

my o fu n c t i o n a l t h e rap y , can b e co n s i d e red .

• If Cla ss II (Pigs 6.26   &   6.27) or Class III elastics are

r eq u i r ed , t h ey sh o u l d b e a t t ach ed p o s t e r i o r l y t o p r em o l a r s

r a t h e r t h an m o l a r s . T h ese ' sh o r t ' e l a s ti c s mi n i m i ze t h e

extrusive effect on the back of the arches.

• The remo val o f acry l ic f rom th e incisor area o f the u pp er

r e t a i n e r is r eco mm en d ed , a l o n g wi th t h e p l acem en t o f a

smal l h o l e i n t h e an t e r i o r r eg i o n as a r emi n d er fo r t h e

t o n g u e . P o s i t i o n er s can b e co n s i d e red d u r i n g r e t en t i o n ,

because of their bite-closing effect (p. 31 I).

F i g .  6 .2 6 Shor t C lass I I e las tics can be help fu l in ma na gin g

an ter io r op en -bi te Class II cases. Here, Class I I elast ics are carr ied

to hooks on lower second premolar tubes .

F i g .  6 .27 In th is C lass II an ter i or o pe n-b i te case, second

premo lars were ex t ra c ted. Shor t C lass I I mechanics were app l ied

to Kobyashi t ies on the lower f i rs t premolars .

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CASE MP

A ma le pa t i e n t , a ge d 12 .7 ye a rs , w i th C la s s II s ke le t a l ba s e s

( A N B 6 ° ) a n d b i m a x i l l a r y p r o t r u s i o n a n d p r o c l i n a t i o n o n

a n a ve ra ge a ng le pa t t e rn o f M M 27° .

F i g .  6 .28

The pa t ient was in the la te mixed dent i t ion with a l l

pe rm a ne n t t e e th de ve lop ing . The re wa s s om e lowe r a n te r io r

crow ding an d an up per mi dl in e shift of 2 m m to the r ight. It

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3 3

O

146

was fe l t tha t denta l correc t ion could be achieved on a non-

extrac t ion bas is . However , in order to re t rac t the inc isors and

achiev e facial profi le impro vem ent , a dec is ion was ma de to

extrac t a l l f i rs t premolars and manage the case as a maximum

a nc hora ge t r e a tme n t . An uppe r pa la t a l ba r a nd a lowe r l i ngua l

arch were placed a t the s ta r t of t rea tment . Headgear support

was used a t n ight in order to achieve t rea tment goals .

Fig. 6.31

Fig . 6 .34

Too th l e ve l ing a nd a l ign ing p roc e dure s we re c omme nc e d wi th

.016 HANT wi re s , fo l lowe d by re c t a ngu la r HA NI ' w i re s. He re ,

the case is seen with rec tangula r s tee l wires and pass ive

t i e ba c ks in p la c e , p r io r to c om me nc e me n t o f c o r re c t ion o f

overje t an d overbi te , fo l lowed by space c losure .

F i g .  6 .37

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M.P.Beginning

12.7 years

1/13/95

F i g .  6.29

SN A

 / 84 •

S N B

A N B

A N  FH

Po-N

  FH

W I T S

G o G n S N

F M

M M

1

  to

 A-Po

1 t o A -Po

1

  to Max

 P lane

1

  to

 M a n d P l a n e ^

7 8

  '

0  mm

-1 0

  mm

1

  mm

' 3 5 °

2 8 °

2 7 °

1 6

  mm

7

  mm

1 2 5 °

98 •

F i g .

  6.30

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F i g .

  6.32

F i g .

  6.33

F i g .  6.35

Fig.

 6.36

F i g .

  6.38

F i g .  6.39

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The pa t ient was asked to wear a

  ']'

  hoo k type o f he a dge a r

during the evenings and nights , toge ther wi th Class II e las t ics .

In this type of case, a   ']'  ho ok head gear can be he lpful in both

re t rac t ion and in t rus ion of upper inc isors in order to achieve

opt imal fac ia l profi le change .

Fig. 6 .40

During space c losure , the lower l ingual a rch was discont inued

bu t the upp e r pa la ta l ba r r e ma ine d in p l a c e to s upp or t upp e r

a nc hora ge .

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Fig. 6 .43

After the rec tangular wires had been in place for 2 months ,

b i t e -ope n ing c u rve s we re in t roduc e d (p . 137) .

Fig. 6 .46

Lower second molars (p . 136) were banded to ass is t in

correc t ion of the lower curve of Spec

  I

  Iere, the case is seen

afte r 16 months of t rea tment . The lower f i rs t molar bands

we re re pos i t ione d .

Fig. 6 .49

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' -.1

F ig .

  6 .47

Fig.

  6.50

F i g .  6 .4 8

F i g .

  6 .5 1

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O

Normal finishing procedures were followed, and appliances

were removed after 23 months of active treatment.

Fig.  6.52

Normal retention was provided, with the lower bonded

retainer extended onto the second premolars.

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150

A

 very pleasing improvem ent in facial esthetics was ob tained .

Because of the decision to extract first premo lars and man age

th e  case as a maximum anchorage treatment, it was possible

to retract upper and lower incisors to near normal positions.

Fig.  6.55

Fig .  6.58

Considerable downward and forward mandibular growth

took place during treatment, which assisted the treatment

mechanics.

SN a t S

M . P . B e g i n

M . P . F i n a l

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Fig. 6 .53

Fig. 6 .54

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SNA / 82

S N B 7 9

A N B / 3

A - N J _ F H

\  Po-N FH

]  W I T S

' GoGnSN

F M

M M

1 to A-Po

1 t o A - P o

1 t o Max P la ne

1 t o M a n d P l a n e

0

- 1 1

- 4

^ 3 8

' 3 1

- "30

7

4

1 0 8

8 6

m m

m m

m m

m m

m m

Fig. 6 .59

P a l a t a l P l a n e &

P a l a t e C u r v a t u r e

M a n d .  S y m p h a s i s

& M a n d . P l a n e

M.P.Begin

. P . F in a l

M. P. B e g i n

M.P.Final

Fig. 6.62

Fig. 6 .63

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73

CASE CW

A fe ma le p a t i e n t , a ge d 10 .3 ye a rs , w i th C la s s  1  d e n i a l b a s e s

on a n a ve ra g e ve r t i c a l pa t t e rn , bu t w i th a de e p ove rb i l e a n d

lowe r inc i s o rs a t  - 1 APo. Fa c ia l p ro f i l e wa s s l igh t ly C la s s

11 w i t h a h i n t o f m a n d i h u l a r r e t r o g n a t h i s m .

F ig . 6 .64

Intraora l ly , the molars were ha lf a uni t Class II b i la te ra l ly . The

lower mi dl in e was 1 m m to the r ight .

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O

152

Fig. 6 .67

Al l pe rma ne n t t e e th we re de ve lop ing , a nd the two re ma in ing

uppe r p r ima ry s e c ond mola r s we re a bou t to be s he d . The

pat ient 's a rch form was assessed as be ing square . The case was

trea ted on a non-extrac t ion bas is .

Fig. 6.70

Mid-s ized meta l brackets (p . 28) were used in th is case

because of the smal l tooih s ize , and the need to ass is t in

m a i n t a i n i n g g o o d o r a l h y g i e n e . C o m m e n c i n g u p p e r a n d

low er a rch wires were .0 16 HANT.

Fig. 6 .73

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S N A

S N B

A N B

A N F H

Po-N FH

W I T S

G o G n S N

F M

7 8 °

' 7 4 °

4 °

- 3 m m

- 1 0 m m

0 m m

3 3 °

2 4 °

M M / 2 7 "

i  t o A -Po

1 t o A-Po

1 t o Max P lan e

1 t o M a n d P l a n e

5 m m

-1 mm

103 •

89 •

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F i g .

  6 .71

F i g .  6 .72

153

F i g .  6 .74

F i g .

  6 .75

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73

Lower second molars were banded a t th is s tage of the

trea tment , to ass is t in overbi te control .

Fig .  6.76

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o

154

The in i t ia l .016 HANT wires were fol lowed by rec tangu lar

.01 7/ .0 25 HANT wires . Here , the case is seen af te r 3 m on th s

of t rea tm ent , wi th pass ive coi l spr ing s in p lace to ho ld space

fo r [he e rup t ing uppe r s e c ond p re mola r s .

Fig.

  6.79

After 6 months of t rea tment , i t was poss ible to p lace upper

and lowe r rec tangular s tee l wires wi th a squ are a rch form.

Onc e the s e ha d be e n in p l a c e fo r 3 mon ths , a dd i t iona l

a n te r io r to rque wa s a dde d , t oge the r w i th s l igh t b i t e -ope n ing

curves .

Fig.  6.85

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F i g .  6 .77

F i g .

  6 .78

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F ig .

  6 .80

F i g .

  6 .81

F ig .

  6 .86

F i g .  6 .87

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The case af te r 8 months . The pa i ieni was asked to wear l ight

Class II e las t ics (100gm). At th is s tage , i l i s necessary lo awai t

uppe r inc i s o r to rque improve me n t be fo re the buc c a l

occ lus ion and inc isor re la t ionship can be f ina l ly correc ted.

A t 18 mon ths in to t r e a tme n t , uppe r a nd lowe r s t e e l

re c t a ngu la r w i re s a re c on t inu ing a nd u ppe r inc i s o r to r que

changes have taken place , a l lowing correc t ion of the buccal

occ lus ion and anler ior overbi le . Lower pass ive t iebacks and

upper ac t ive t iebacks are in p lace .

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Fig.  6.91

156

Fig . 6 .94

Norma l s e t t l i ng p roc e dure s we re fo l lowe d .

  I

  lere, ihe case is

s e e n imme d ia t e ly p r io r to a pp l i a nc e re mova l .

Fig . 6 .97

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F i g . 6.89

F i g .

 6.90

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F i g .

 6.92

F i g . 6.93

F i g .

 6.98

F i g .

 6.99

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The case af te r appl iance removal . Act ive t rea tment l ime was

2 3 m o n t h s .

Fig . 6 .100

Norma l re t e n t ion p roc e dure s we re fo l lowe d . The ra d iog ra phs

indica te tha t ther e is ad eq ua te space for the dev elop ing th i rd

mola r s .

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Fig . 6 .103

A pleas ing im pro ve m ent in facia l profi le was achieved in th is

case . The pos i t io n of the inc isors in the facia l profi le was c lose

to idea l in te rms of vert ica l pos i t ioning, A/P pos i t ion, and

to rque .

158

Some fa vora b le g rowth oc c u r re d du r ing t r e a tme n t , wh ic h

ass is ted in achieving good overbi te control and reaching the

trea tment objec t ives .

Fig . 6 .106

Fig.  6.109

SN a t S

C . W . B e g i n

C . W . F in a l

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Fig.  6.104 Fig .  6.105

Fig .

  6.107

P a l a t a l P l a n e &

P a l a t e C u r v a t u r e

C.W.Begin

C.W.Final

Fig.

  6.110

S N A

S N B

A N B

A-N FH

Po-N FH

W I T S

G o G n S N

F M

M M

1 to A-Po

1 t o A -Po

1 t o M a x P l a n e

1 t o Man d P lane

7 5 °

7 4 °

1 °

- 5 mm

-9 mm

-2 mm

3 4 °

25 '

2 4 "

5 m m

2 m m

119 •

91 °

M a n d . S y m p h a s i s

& M a n d . P l a n e

C.W.Begin

Fig.

  6.111

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CHAPTER 7

An o v erv iew o f Class II t r eatm en t

In t roduct ion 162

The shift in emphasis from molars to

incisors 162

The concept of ' ideal ' incisor posi t ion in t reatment

planning 162

Posi t ioning of lower incisors in Class I I

cases 178

Control of the A/P posi t ion of lower

incisors 178

Movement of lower incisors in the mandibular

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Planned incisor pos it ion 162

The l imitat ions of or tho don t ics 163

The surgical/non-surgical decision in (Mass II

treatment 163

Identifying severe Class II cases 164

The four- s tage t r ea tm ent p la nn ing process 166

Setting a PIP for up pe r incisors 166

The lower inciso rs 166

The rem ainin g lower teeth 167

The remain ing uppe r teeth 167

PIP com po ne nt s in Class II t r ea tm ent 168

A/P com pone nt 168

Torque com pon ent 169

Vertical co m po ne nt 169

Upper incisor m ov em en t in Class I I cases 170

Mesial mo vem ent of upp er incisors 170

Distal movement of upper incisors in cases with

upper ante rior spacin g 172

Distal movement of upper incisors after upper

premo lar extractions 173

Distal movement of upper incisors in non-

extraction cases wit ho ut spacin g 173

Control of up pe r incisor torq ue 174

Vertical con trol of incisors 177

bone 179

Favorable change in mandibular length or

position 180

Ma ndibu lar growth 180

Augmenta t ion of mandibular pos i t ion wi th

functional applian ces? 181

Favorable condylar reposi t ioning of the

mandible 181

O rtho pe dic vertical con trol of the maxilla? 181

Unfavorable condylar changes , causing reduced

m an dib ula r length 182

Unfavorable condylar reposi t ioning of the

mandible 183

Case LJ An ad ul t Class II dee p bi te case wi th

ext rac t ion of upper f i r s t premolar s and a l l t h i rd

molar s 184

Case TC A non -extr act io n case, Class I skeletal ly

an d mildly Class II den tal ly 192

Case TS A Class 11/1 no n-e xtra ct io n twin blo ck

case 198

Case DO An adu l t Class I I /2 which requi red

m ola r ext rac t ions 206

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INTRODUCTION

The subjec t of Class II t rea tment is extens ive , and an in-depth

discuss io n is bey ond the scope of th is text. Th e purp ose of

th is chapter , therefore , i s to present an overview of th is

subjec t , emphas iz ing the key aspec ts of d iagnos is , t rea tment

p la nn ing , a nd t r e a tme n t me c ha n ic s .

The sh i f t i n emphas is f r om mo la rs to

inc isors

W hen A ngle in t ro duc ed his c lass i f ica t ion in the la te 1920s ,

o r thodon t i c s foc us e d p r ima r i ly on the mola r r e l a t ions h ip a s

Class I, Class II, or Class III . Ko n-ex lrac t io n t rea t me nt and

e xpa ns ion wa s ge ne ra l ly the t r e a tm e n t o f c ho ic e . In the 1940s

T w e e d

1

  m ove d the em pha s is to the lower inc isors , wi th

e x t ra ct ion t r e a tme n t b e c om ing m ore p re va le n t . Th i s wa s

c learly a reac t ion agains t the shortcomings of excess ive non-

The con cep t o f ' i de a l ' i nc i so r po s i t i on i n

t r e a t m e n t p l a n n i n g

W ith the a dve n t o f improve d o r thodon t i c a nd s u rg ic a l

t e c hn iq ue s , e m pha s i s ha s s h i f te d m ore towa rd the u ppe r

inc isors as a s ta r t ing point . Today, i t i s poss ible to base

t re a tme n t p l a nn ing on the pos i t ion o f the uppe r inc i s o rs ,

ins tead of us ing the molars or the lower inc isors as a s ta r t ing

point . At the s ta r t of t rea tment p lanning, i t i s poss ible to

e nv i s ion a n ' i de a l ' pos i t ion fo r the uppe r inc i s o rs . l o r ma ny

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t he e m pha s i s on the lowe r inc is o rs , w i th m in imiz e d e m pha s i s

on the upper inc isors , was due to the fac t tha t surgica l

correc t ion was not ava i lable a t the t ime, nor was improved

fac ia l appearance with funct ional appl iances . The

orthodont is t was re lega ted to dec iding a s table lower inc isor

pos i t ion a nd the n mov ing the uppe r inc i s o rs in to c on ta c t

with the lowers .

I t sho uld a lso be em ph as iz ed tha t in m any Class I

t r e a tme n t s the ma loc c lus ion ma y be c o r re c t e d by too th

a l ignme n t on ly , a c c e p t ing the pos i t ion o f the uppe r a nd lowe r

inc isors in the face . This is so-ca l led ' to oth a l ig nm ent '

o r thodon t i c s , a nd i t c a n be s t ra igh t fo rwa rd us ing the

preadjus ted bracket sys tem.

Howe ve r , t he ma jo r i ty o f o r thodon t i c c a s e s re qu i re c ha nge s

in inc i s o r pos i t ion . In a dd i t ion to ' t oo th a l ignme n t ' , mos t

c a s e s re qu i re more c ha l l e ng ing 'de n tu re -pos i t ion ing '

procedures . For example , a l l malocc lus ions with a Class II or

Class III inc isor re la t ionship wil l require t rea tment p lanning

a nd the n t r e a tme n t me c ha n ic s to a c h ie ve no t on ly p l e a s ing

too th a l ignme n t , bu t a l s o de n tu re pos i t ion ing in the fa c i a l

complex for opt imal fac ia l es the t ics .

c a s e s , t r e a tme n t me c ha n ic s c a n the n be p l a nne d to pos i t ion

the inc isors idea l ly , and subsequent ly to f i t a l l the other tee th

around th is idea l pos i t ion. In other cases , the ' idea l ' inc isor

pos i t ion wil l not be a rea l is t ic goal , and a less than idea l , but

nonethe less acceptable , pos i t ion for the inc isors needs to be

used as a bas is for t rea tment p lanning.

Planned inc i so r pos i t i on

Planned inc isor pos i t ion (PIP) may be defined as :

The intended end-of-treatm ent position for upper incisors.

In some cases , the perce ived idea l upper inc isor pos i t ion

wil l be a rea l is t ic t rea tment goal , and can become the PIP for

tha t case . In o ther cases , the idea l inc isor pos i t ion may not be

a rea l is t ic goal , for various reasons . In such cases , the

perce ived idea l inc isor pos i t ion has to be adjus ted to re f lec t

the l imit ing fea tures of the case , such as lack of coopera t ion

or growth potent ia l . Then a PIP has to be accepted which is

no t idea l , but which is accep table for the case .

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The l imi tat ions of or thodont ics

In some cases, it will become evident during treatment

planning that there are major limiting features, such as

skeletal disproportion, which cannot be resolved by

orthodontics alone. It is important to identify such cases, and

consider a surgical/orthodon tic solution in order to achieve

an acceptable PIP. If there are major limiting features, it is

normally belter not to commence treatment on the basis of

orthodontics alone. In such cases, there is a probability of

adverse facial change, due to an unacceptable end of

treatment incisor position, as a consequence of attempting to

achieve a 'better bite' only.

D r G . W i l l i a m A r n e t t

a

>

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O

n

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1/1

73

m

>

The surgical/non-surg ical decis ion in Class II t rea tm en t

The soft tissue ceph alom etric ana lysis, or STCA, has be en advoca ted by Arnett et al

2

-

3

-

4

  as an aid for orthodontists and surgeons

in treatment plannin g. It recomm ends analysis using a true vertical line (TVL) through subnasa le, with natural head posture . It

H

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may also be used to quantify favorable or unfavorable change in the profile after overjet reduction, and hence has an important

potential role in post-treatment analysis and in research. Ihe STCA includes normal values for many aspects of facial profile and

harmony, but in the following theoretical situations only seven of these will be considered (Fig. 7.1). For reasons of clarity, all

other STCA values will be disregarded in this discussion, and it will be assumed that the upper- and mid- thirds of the facial

profile are close to ideal, and that the upper incisors are well positioned.

TVL

57

  \

Color codes used with

the Arnett soft tissue

cephalometric analysis

Black  = within 1  SD

Green

 =

 within 2  SD

Blue  = within 3 SD

Red  = more than 3 SD

F ig .  7 .1 Only seven measurem ents f ro m the STCA are inc luded he re. The upp er inc isor torq ue is mea sured re la t ive to th e m ax i l lary

occ lus al p lane and the l ow er i nc i s or t o rqu e i s m eas ured re la t i v e t o t he m an d ibu la r oc c lus a l p lane . In t h i s d iag ram , t he f o l l o w i ng a re

pro jec ted to t rue ve r t ica l l ine (TVL) : Sof t tissue 'A ' po i nt , up per l ip ant er io r , low er l ip ante r ior , sof t t issue 'B ' po int , and so f t t issue

pogo n ion . B lac k num bers a re w i t h i n 1 SD o f no rm a l .

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.

Identifying severe Class II cases

Or tho do nt i cs can be rel ied upo n to achieve a go od o ut co m e for mo s t pa t ien ts wi th Class I or mild Class II ske le ta l bases .

I Iowever , i t i s im por tan t to recog nize tho se Class II cases whic h hav e a majo r ske le ta l d isp rop ort ion a t the t im e of assess me nt .

For such indiv iduals , i t wi l l be necessary to cons ider a sur gic a l /o r th od on t ic solut ion (Fig . 7 .2) . Tr ea tm ent o n th e bas is of

o r tho don t i c s a lo ne s hou ld b e d i sc a rde d a s a pos s ib i l it y , un le s s the re i s a r ea l p ros pe c t , i n a g row ing ind iv idua l , o f a c h ie v ing

favorable ske le ta l change with funct ional appl iances .

Th e theore t ica l Class II / l t re a tm ent s i tua t ion s , A, B and C, on t he oppo s i te page sh ow so m e of the pot ent ia l d i ff icul ties .

TVL TVL

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F i g .  7 .2 In the above d iagrams, the d i f fe r en t co lors o f the Arn et t ana lys is he lp to h igh l igh t the areas an d qu an t i ty o f fac ia l

d is pro por t ion . The r igh t ex amp le is no rm al . The center exam ple is a mode ra te C lass

 11/1

 ma locc lus ion wh ich m ay be cons ide red fo r

t re a tm en t by or th odo nt ic s a lone. In the example on the le f t , i t is c lear th a t the sever i ty o f the pro b le m m ay requ ire  a  c o m b i n e d

or t hod on t ic an d surg ica l assessment , and tha t t rea tm ent o n the bas is o f o r th od on t ic t re a tm ent a lone may need t o be d iscarded as a

poss ib i l i ty , unless majo r ske le ta l change can be ach ieved, fo r a gr ow in g in d iv id ua l , w i t h fu nct io na l app l iances (Case TS , pp 198-205) .

S i t u a t i o n A -  or th od on t i c m a s k ing o f a m i ld C la s s I I . If t he unde r ly in g s ke let a l C las s II d i s c re pa nc y is mi ld , i t ma y be

de c ide d to fo l low a t r e a tme n t p l a n ba s e d on o r th odo n t i c s a lon e . Th e o r th odo n t i s t w i l l p rov ide c o r re c t ion by 'ma s k in g ' t he

und erly ing Class II d iscrep ancy with denta l com pen sa t ion . This wi l l involve s l ight re t roc l ina l ion o f up per inc isors an d/ or

p roc l ina t ion o f lowe r inc is o rs . C o od pa t i e n t c oo pe ra t io n w i th C la s s II e l a st i cs a nd /o r a he a dge a r w i l l no rma l ly b e ne e de d in

th i s t ype o f t r e a tme n t . Tre a tme n t s hou ld l e a d to a good de n ta l a nd a n a c c e p ta b le fa c i a l ou tc ome (F ig . 7 .3 ) .

:

57 ,

64

TVL

T, 0

»4

'•-•••

 u

/: ft

8

.

-6

TVL

Color codes used with

the Arnett soft tissue

cephalometric analysis

Black  = within

 1

  SD

Green =

 within 2

 SD

Blue  = within 3 SD

Red  = more than 3 SD

F i g .  7 .3 In the theo re t i ca l s i tua t ion A , goo d

correc t ion has been ach ieved by de nta l

com pens at ion , ass is ted by a smal l am ou nt o f

favorab le growth . Many mi ld C lass I I cases can

be successfully man age d in thi s way, in

g row ing ind iv idua ls .

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Situation B - attempted orthodon tic masking of a more severe Class II skeletal problem . If the unde rlying skeletal

Class II discrepancy is moderate to severe, a treatment plan based on orthodontics alone carries risks. If the orthodontist

attemp ts correction of the bite by 'masking' the Class II discrepancy with d ental co mpe nsation, there is a probability of

over-retraction of the upper incisors and a very unfavorable change in facial profile (Pig. 7.4). This also leaves the upper and

lower incisors in a position which is unsuitable for successful orlhognathic surgery, if this is to be provided later. Further

orthodontic treatment will be required to decompensate the anterior teeth, so that maximum benefit can be obtained from

surgery.

>

-z.

O

<

m

TO

<

O

n

r-

>

TVL

TO

m

>

F i g .  7 .4 In the the oret ic a l s i tua t ion B, an

at tempt has been made to cor rec t a severe

Class I I problem by or thodont ics a lone, and

the re has been un fav o rab le c hange i n f ac ia l

pro f i le . This is c lear ly seen in th e increas ed

num ber o f r ed A rn e t t m eas urem e nts in t he

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r i gh t d iag ram . There has been f l a t t e n in g o f

t he up per l i p , w i t h r educ ed c onv ex i ty , t o g i v e

the ' o r t ho do n t i c l oo k ' w h ic h has been m uc h

cr i t ic ized in the past. The STCA c lear ly shows

th is .

Situation C -   combined orthodontic and surgical correction of a  severe Class II/l malocclusion.  Patients are

understandably anxious to avoid surgery, but for many severe cases, in non-growing individuals, it offers the best possible

outcom e in dental a nd facial terms (Pig. 7.5). If ma ndibu lar advan ceme nt surgery is deemed necessary, the surgeon may

wish to delay this until age 16 or later, to allow m aturation of the lem poro ma ndibu lar joints, so they are able to supp ort

the position of the corrected man dible.

TVL

F i g .  7 .5 The theor et ica l s i tua t ion C is the same

at the s tar t as s i tua t ion B. How ever , th e severe

Class I I problem has been cor rec ted by

c om b ined s u rge ry and o r thodon t i c s . The

favo rable chan ge in fac ia l prof i le is c lear ly seen

in t he b lac k A rne t t m eas urem en ts i n t he r i gh t

d iag ra m . A l t ho ug h pa t i en t s a re anx ious t o

avoid surgery , i t may of fer the bes t poss ib le

outcome in denta l and fac ia l terms for severe

cases , and i t is ap pro pr ia te to i n f or m t he

pat ient o f th is .

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THE FOUR-STAGE TREATMENT PLANNING

PROCESS

o

<

m

<

o

n

r-

>

on

m

>

H

Dur in g tr e a tme n t p l a n n ing , t he th ink ing goe s th roug h fou r

stages:

Stage 1 - se t t i n g a PIP fo r th e up pe r

inc isors

What is the ideal position for the upper incisors in the face in

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te rms of A/P pos i t ion, torque , and vert ica l pos i t ioning? Can

ideal up per inc isor pos i t ion be achieved? If not , can an

a c c e p ta b le inc i s o r pos i t ion be a c h ie ve d by o r thodon t i c s a lone ,

or is it necessary to consider maxillary surgery? In this way, a

PIP is de termined for the case .

F i g .  7 .6 A t the s tar t o f t rea tm en t p la nn ing , i t is necessary to

det erm ine a 'p lanne d inc isor pos i t io n ' , o r P IP , fo r the upp er

incisors. In some cases, the perceived ideal upper incisor

pos i t ion is a rea l is t ic t re a tm ent

  g o a l ,

  a nd can be used as th e PIP.

In other cases, a PIP can be accepted which is not ideal, but

wh ich is acce ptab le for the case.

Stage 2 - th e low e r inc isors

Is i t poss ible to pos i t ion the lower inc isors in good

re la t ionship to the PIP for the upper inc isors? Can the

re qu i re d lowe r inc i s o r pos i t ion be a c h ie ve d by o r thodon t i c s

alone? If not, i t will be necessary to modify the PIP for the

upper inc isors (which may not be feas ible) , accept a t rea tment

goal wi th a less than idea l inc isor re la t ionship , or cons ider

s u rge ry to the ma nd ib le .

F i g .  7 .7 The second s tage o f t re a t m en t p lan n in g concerns the

lowe r inc isors , and how to pos i t ion the m in go od re la t i onsh ip

to th e P IP fo r the upper inc isors . If th is cannot be ach ieved by

or thodont ics a lone, i t w i l l be necessary to modi fy the

  PIP fo r

the uppe r inc isors , o r cons ider ma nd ib u lar surgery .

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Sta ge 3 - t h e r e m a i n i n g l o w e r t e e t h

I

  low can the rest of the lower teeth be positioned to fit the

planned lower incisor position?  I  low is any lower spacing to

be managed? Does this need to be an extraction case to deal

with lower crowding? The dental VTO (p. 227) can be used at

this stage of the planning process, to reach a correct extraction

decision. The primary factors are crowding, curve of Spee, and

midlines. The secondary factors are expansion, distalization of

molars, inter-proximal enam el reduction, and 'E' space. The

orthodontist 's view about the possible amount of expansion

and the acceptable degree of lower incisor proclinaiion will be

variables.

O

<

m

<

o

n

>

c/i

m

>

F i g .  7 .8 T he th i rd t rea tm en t p lann ing s tage concerns low e r

arch crowding or spac ing, and the ex t rac t ion dec is ion . How can

t h e

  res t o f the lower tee th be pos i t ioned to f i t the p lanned

lower inc isor pos i t ion , and w i l l ex t rac t ions be needed?

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Stage 4 - th e rema in in g up pe r te e th

How can the rest of the upper teeth be positioned to fit the

PIP for the upper incisors? How will upper crowding or

spacing be dealt with, and what treatment mechanics will be

needed to correctly position the upper molars and premolars?

The dental VTO will confirm the required tooth mov eme nts

for upper canines an d molars.

F i g .  7 .9 F ina l ly, in the t rea tm en t p l ann ing process, i t is

necessary to dec ide how to pos i t ion the res t o f the upper tee th

correc t ly . How w i l l c rowding or spac ing be dea l t   w i t h ,  and w ha t

t rea tment mechan ics w i l l be needed?

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PIP COMPONENTS IN CLASS II

TREATMENT

-

o

<

m

<

o

-n

n

r~

>

H

33

m

>

For each case, it is necessary to set a PIP as a treatme nt goal

which will result in the upper incisors having correct A/P and

vertical positioning, w ith approp riate torque . Each

orthodontist will have a view about what the exact goals for

the upper incisor position sho uld be for a particular case,

although there is likely to be broad consensus about the

approximate treatment needs. It is beyond the scope of this

text to discuss and define those goals in detail. However,

general comments will be made, based on conventional

cephalom etric values and also on the Arnett analysis.

2

"

4

T h e a n te r o - p o s te r i o r c o m p o n e n t o f P IP i n

C lass I I t rea tment

Traditionally in orthodontics the upper incisor A/P position

has been related to the APo line with a conventional

APo +6mm

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cephalometric value of

 +6

  mm (Fig. 7.10). The Arnett analysis

relates upper incisor position to a true vertical line (TVL), and

uses the term MXI-TVL, which is the linear measurement

from the lip of the upper incisor to the true vertical line. The

male upper central incisor tip is ideally -1 2 mm to the line

and the female is at -9 mm (Fig. 7.11).

F i g .  7 .1 0  I n t rad i t i ona l o r th odo n t i c t rea t me n t p lann in g , uppe r

inc isor pos i t io n has been re la te d to the APo l ine , w i t h no

d i f fe rence in the normals between males and females .

Male

-12mm

Female

-9mm

F i g .

  7 .1 1

  The Arne t t ana lys is re la tes upper inc isor pos i t ion to a t rue ver t ica l l ine (TVL) and requ ires d i f fe r en t idea ls fo r m ales and

females .

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The to rq ue com po ne nt o f PIP in Class II

t rea tment

Traditionally in orthodontics upper incisor torque has been

related to the m axillary plane, with a cephalom etric value of

110° to 115° being a typical goal (Fig. 7.12). The Arnett

analysis relates upper incisor torque to (he maxillary occlusal

plane, and lower incisor torque to the mandibular occlusal

plane, with the male upper central incisor torque being

ideally 58° and the female 57° (Fig. 7.13). More information

on upper incisor torque is given on pages 174-176.

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F ig .

  7 .12 I n t r ad i t i on a l o r t h od on t i c t r ea tm e n t p lan n ing , upper F i g . 7 .13 The A rn e t t ana ly s is r e la tes upper i nc is o r t o rq ue to

incisor to rq ue is re la te d to th e ma x i l lary p lane . the upp er occ lusal p la ne, and has s l ight ly d i f fer en t va lues fo r

m a les and fem a les .

The ver t ica l component of  PIP  in Class II

t r ea tmen t

The Arnett analysis quantifies the vertical positioning of upper

incisors, and requires an overbite of 3mm, with upper incisor

exposure being 4mm below the relaxed upper lip in males

and 5mm in females (Fig. 7.14).

Orthodontic cephalometry has not provided clear goals for

vertical positioning of the upper incisors. The high lip-line is a

contributory factor in Class 11/2 malocclusions, and there is

an acknowledged need to procline and intrude upper incisors

in such cases, to assist in stability.

F i g .

  7 .14 C onv e n t i ona l o r t ho do n t i c ana ly s is does no t p rov ide

c lear goals for ver t ica l upper inc isor pos i t ion. In cont ras t , the

Arnet t analys is quant i f ies inc isor overb i te and inc isor exposure,

w i th l ips at res t .

Male 4mm

Female 5mm

lip  exposure

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UPPER INCISOR MOVEMENT IN CLASS II

CASES

o

<

m

<

O

n

i

-

>

73

m

>

I lav ing decided o n a PIP for a case, con t ro l l ed u ppe r incisor

too t h m ove m ent i s nee ded to ach ieve the goal . It i s helpfu l to

co n s i d e r (h e u p p er a r ch i n i so l a t i o n wh en p l an n i n g t r ea t men t

mechanics to posi t ion the upper incisors a t PIP . I t i s helpfu l

f i rs t to p lan the upper incisor correct ion , and second to p lan

t h e l o wer i n c i so r co r r ec t i o n . T h i s a l l o ws c l ea r an d sy s t emi zed

o rg an i za t i o n o f t r ea t men t mech an i cs .

W h e n p l a n n i n g u p p e r a r c h t o o t h m o v e m e n t s , t h e l o w e r

arch i s re levan t as a possib le source of anchorage, i f Class I I

mech an i cs a r e r eq u i r ed . Al so , p ro p er o v erb i t e co n t ro l i s

nee ded (Ch . 6 ) , so that lowe r incisor posi t ion w i l l no t h in der

u p p e r ar ch i nc i so r mo v em en t . T h ese co n s i d e ra t i o n s ap a r t , t h e

max i l l a ry i n c i so r t o o t h mo v emen t s can an d sh o u l d b e

p l an n ed wi t h o u t r eg a rd t o t h e l o wer a r ch .

In the fo l lowing pages , typ ical t reatment s i tuat ions wi l l be

d i scu ssed , g i v i n g d e t a i l s o f t h e r eco mmen d ed M BT

IM

t r ea t m en t mech an i cs fo r each r eq u i r ed m o v e m en t :

• M es i a l mo v em en t o f u p p e r i n c i so r s .

• D i s t a l m o v e m en t o f u p p er i n c iso r s i n cases wi t h u p p er

an t e r i o r sp ac i n g .

• Di s t al m o v e me n t o f u p p er i n c i so r s a f te r u p p er p re mo l a r

ex t r ac t i o n s .

• D i s t a l m o v e me n t o f u p p er in c i so r s i n n o n -ex t r ac t i o n cases

wi t h o u t sp ac i n g .

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Mesial movement of upper incisors in

Class II treatment

In Class 11/2 cases, the upper incisors are typically too far back

in the face. In the mod ern th ink in g , which i s con cern ed mo re

wi th the incisor posi t ion in the face, the Class I I molar

r e l a t i o n s h i p (wh i ch An g l e em p h a s i ze d ) is s eco n d ary t o i h e

re t ro d i n ed u p p er an d l o wer i n c i so r s . Du r i n g l ev e l i n g an d

a l i g n i n g o f t h e u p p er a r ch , t h e u p p er i n c i so r s mo v e mes i a l l y ,

b r ing ing (hem closer (o the PIP , and the Angle 's c lass i f icat ion

b eco m es C l ass 1 1 /1 . I n ad o l esce n t t r ea t m en t , t h i s en su i n g

Cl ass I l / l case can n o rm al l y b e co r rec t ed b y co n v en t i o n a l

o r t h o d o n t i c s , b u t i n so me ad u l l cases man d i b u l a r su rg e ry wi l l

b e r eq u i r ed .

The requ i red mesial change in upper incisor posi t ion i s

ach i ev ed mai n l y b y t o o t h m o v em en t . I n o r t h o d o n t i c

cephalometry , (he SKA is used (o record (he posi t ion of the

maxi l lary skeletal base, and therefore th is may suggest that

mes i a l mo v emen t o f (h e max i l l a h as co n t r i b u t ed t o t h e

imp rove d A/P posi t ion of (he upp er incisors . Th is i s beca use

'A' po in t , whic h i s a d i f ficu lt cep halo m etr ic p o in t to record ,

lends to fo l low the change in the upper incisor roo t posi t ion

dur ing C lass 11 /2 level ing (Case D O, p . 212 ) . The perceived

change in 'A ' po in t o f ten g ives a g reater skeletal base

d iscrep ancy for the en su ing Class I I / l pat te rn than w as

ev iden t in the s tar t ing Class I I /2 malocclusion .

F i g .

  7 .15  'A ' po in t is d i f f icu l t t o measure accurate ly . I t tends to

fo l l ow c hanges i n pos it i on o f upper i nc is o r r oo t s du r ing upper

arch a lig nm en t o f Class 11/2 cases.

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In practical terms, the opening stages of Class 11/2 cases

ma y be ma na ge d in two wa ys :

1.

  Upper a rch t rea tment may be s ta r ted f i rs t , wi th no

a pp l i a n c e (o r e l s e on ly lowe r mo la r ba nd s ) p l a c e d on the

lower tee th (Fig . 7 .16A). After reaching the rec tangular s tee l

work ing w i re in the uppe r a rc h , t he lowe r a pp l i a nc e ma y

the n be p l a c e d , a nd lowe r l e ve l ing c omme nc e d .

2 .  Upper and lower f ixed appl iances may be placed from the

outse t , wi th an upper acryl ic b i te p la te be ing worn for the

ope n ing fe w mon ths ( f ig . 7 .16B ) , t o f re e the b i l e a nd

pre ve n t da ma ge to the lowe r b ra c ke t s (C a s e DO, p . 209) .

As upper a rch leve l ing occurs , the removable bi te p la te

gradual ly becomes a poor f i t , and can be discarded af te r i t

has served i ts purpose .

Upper a rch leve l ing and a l igning are achieved by

proc e e d ing th rough the no rma l a rc hwi re s e que nc e s . Ope n ing

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wires a re normal ly mult is t rand, because there is of ten a need

for anter ior s tepping to avoid excess force on the upper

inc isors a t the s ta r t . Upper a rch length increases during the

first few mo nt hs , and ben dba cks sho uld b e 1 m m dis ta l to the

molar tubes to a l low this in mos t cases ( l" ig . 7 .16C). The

typica l ear ly changes may be seen on Case DO, pages 208 &

2 0 9 .

F i g .

  7 .1 6 A  Uppe r arch t re at me nt m ay be s tar ted f i rs t in C lass

I I / 2 t r ea tm en t .

F i g .  7 .1 6 B

  A n upp er ac ry l ic b i t e p la te m ay be w o rn i n t h e ea r l y

mo nths of C lass I I/2 cor r ec t io n. (A l tern at ive m etho ds of o ver b i te

control are discussed in Chapter 6, p. 134.)

F i g .  7 . 1 6 C

  Bendbac k s s ho u ld be  1 m m d i s ta l t o m o la r t u bes

dur ing l ev e l i ng and a l i gn ing t o a l l ow a r c h l eng th t o i nc reas e .

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Dis ta l movemen t o f uppe r i nc i so rs i n

c as es w i t h u p p e r a n t e r i o r s p a c i n g

Some Class

 11/1

 cases have upp er incisors which are

demonstrably too far forward in the face. If this is associated

with anterior spacing, it is a relatively routine procedure to

gather up the upper incisors and retract them into the

available space. (The mechanics have been likened to using a

piece of rope to gather up a group of marbles on a

tablecloth!)

Sliding mechanics are used, on a normal working steel

rectangular wire, and active tiebacks achieve the necessary

retraction and space closure, sometim es augm ented by a light

four-link anterior elastic chain. It is necessary to ensure that

good lower arch leveling has been achieved beforehand.

Appropriate anchorage support from an upper palatal bar, a

sleeping headgear, or Class II elastics may be needed. Typical

treatment mech anics are shown d iagramma tically (Tigs 7.17 &

7.18) and may be seen in Case DO, page 209.

F i g .

  7 .17

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F i g .  7 .18

F ig s 7 .1 7

  a n d

  7 .1 8

  I f the re is an t er io r spac ing, s l id ing m echan ics on a .019/ .025 s tee l rec tangu lar w ire may be used to re t rac t incisors

and c lose spaces. Arc hwir e hook s shou ld be c lose to u ppe r la tera l inc isor b rackets , to av o id im p in ge me nt o n t o can ine brackets as the

space closes. Anchorage support can be provided from a palatal bar, headgear, or Class II e lastics.

F i g .

  7 .1 9

  La tera l v iew o f s l id ing mechan ics a f te r upper f i rs t p remola r ex t rac t ions . W i th ou t anchora ge suppor t (A) , rec ip roca l space

c losure norm al ly occurs . W i th anc horage s uppo r t (B) , i t is poss ib le to re t rac t th e s ix an ter io r tee t h in to the space ava i lab le an d

main ta in A /P pos i t ion o f molars .

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Distal  movement o f upper  incisors after

upper premolar ex t rac t ions

Where poss ible , lower premolar extrac t ions a re genera l ly

avoided in Class 11/1 cases , because of the need to mainta in a

mesial posi tio n for lowe r incisor s. The refo re, few Class 11/1

cases a re t rea ted by extrac t ion of four premolars . I f four

prem olars need to be taken, i i i s of ten ap pro pri a te to cho ose

upper f i rs t premolars and lower second premolars , to ass is t

t r e a tme n t m e c ha n ic s . A s ma l l nu mb e r o f c as e s ma y be t r e a t e d

to   a  Class II molar re la t ionship , ' ' fo l lowing extrac t ion of two

upper premolars (Case I .J ,  p .  184).

Sl id ing mechanics a re used to re t rac t upper inc isors a f te r

p re mola r e x t ra c t ions , on a no rma l work ing s t e e l r e c t a ngu la r

wire. Th e retra ction force is deliv ered from active tiebacks . A

s ma l l a moun t o f a dd i t iona l t o rque ma y ne e d to be be n t in to

the ante r ior region of the upp er rec tangular wir e in the inc isor

region, and excess re t rac t ion force should be avoided. In th is

way,  uppe r inc i s o r to rque c on t ro l c a n be ma in ta ine d du r ing

overjet reduction.

Appropr i a t e a nc hora ge s uppor t f rom e i the r a n uppe r

Distal movement of upper incisors in

non-extrac t ion cases wi thout spac ing

In some Class 11/1 cases , i t may be dec ided tha t the t rea imeni

s hou ld be on a non-e x t ra c t ion ba s i s, a nd tha t t he upp e r

buccal segments need to be moved dis ta l ly , to a l low

subsequent re t rac t ion of the upper inc isors toward PIP. I f the

mo ve m e n t i s min ima l (1 -3 m m ) , f ir st mo la r ro t a t ion s o lve s

mo st of the pro ble m (Fig . 7 .2 1) . A head gear an d s l id ing j ig

are he lpful in th is s i tua t ion.

  I

  lowever , when ihe requ ired

mo ve m e n t i s 3 m m or m ore , t h i s be c o me s a c ha l l e ng ing

s i tua t ion for the pa t ient and orthodont is t a l ike , i r respec t ive of

the t r e a tme n t me c ha n ic s in u s e .

There wil l be a requirement to use sophis t ica ted t rea tment

me c ha n ic s to move uppe r mo la r s a nd the n p re mola r s d i s t a l ly ,

us ing one of the many devices ava i lable for th is purpose ,

no rma l ly s uppor t e d w i th he a dge a r . The re a re c l a ims in the

l i te ra ture

6

  tha t th is can be achieved on a regular bas is , but

on ly the mos t c oope ra t ive pa t i e n t w i l l a c h ie ve the p l a nne d

too th m ove me n t s . Typ ic a l t r e a tm e n t me c ha n ic s are s ho wn in

s e que nc e s on pa ge s 194 a nd 195 .

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palatal bar, a sleeping headgear, or Class II elastics may be

needed (Fig . 8 .12, p . 225) , or f rom a combinat ion of these . I t

is  necessary to ensure tha t good lower a rch leve l ing has been

achieved beforehand, so tha t the overbi te is minimal , and

lower inc isors wi l l not in terfere wi th the re t rac t ion process .

Diagrams of typica l t rea imeni mechanics a re shown (Figs 7 .19

& 7.20) an d may be seen in Case IJ on page 184.

Th i s t r e a tme n t a pp roa c h re s u l t s i n a long t r e a tme n t t ime ,

a nd the p l a nne d t re a tme n t goa l s a re no t a lwa ys re a c he d .

The re fo re , i n s ome c a s e s , t he a u tho rs w i l l a ba ndon the non-

e x t ra c t ion c o nc e p t a nd c o ns ide r lo s s o f uppe r s e c ond

m o l a r s .

7

  ' ' This grea tly fac i li ta tes the t rea tm ent m echa nics , an d

there is evidence

1

" tha t uppe r th i rd m o la r s s ubs e q ue n t ly e rup t

in to good po s i t ion in mo re tha n 8 0% of c a s es (C a s e DO,

p.

  21 5) . I f t h i rd m o la r s a re a bs e n t o r poo r ly s i tua t e d , t he n

uppe r b i c us p id e x t ra c t ion ma y be more a pp ropr i a t e .

F ig .  7 .20 Occ lusal v iew of s l id ing mecha nics , used to re t rac t

upper i nc is o rs a f t e r p rem o la r ex t r ac t i ons . W i th anc horage

support from a headgear, a palatal bar, or Class I I elast ics, i t is

pos sib le t o m a in ta in t he pos i t i on o f upp er m o la r s and re t r ac t

the s ix an ter io r tee th in to the avai lab le space.

F i g .  7 .21 C or rec t i on o f upper f i r s t m o la r r o ta t i on c an p rov ide

1-3 mm of favorable d is ta l movement of the buccal sur faces

tow ard s C lass I. The bend back sh ould be 2-3 mm dis ta l to the

end o f t he f i r s t m o la r t ube , o r t he re c an be res t r i c t i on o f

r o ta t i ona l c o r rec t i on .

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Control of upper incisor torque

In June 2000, Fastlighi" presented a discussion on the facial

'tetragon' con sisting of the following four angles:

• Uppe r incisor 10 palatal plane

• Lower incisor to man dibular plane

• Inter-incisal angle

• Maxillary/mandibular plane angle (Fig. 7.22).

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F i g .  7 .2 2

  Fas t l i gh t ' s t e t r agon .

By dividing the tetragon in half,  two triangles are formed

The upper triangle has angles as follows:

• Palatal plan e to occlusal plan e

• Up per incisors to palatal plane

• Uppe r incisors to occlusal plane (Fig. 7.23 ).

F i g .  7 .2 3

  T r i ang le f o rm ed f r om the upper pa r t o f Fas t l i gh t ' s

t e t r a g o n .

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The lower t r iangle has angles as fo l lows:

M a nd ibu la r p l a ne to oc c lus a l p l a ne

Lower inc isors to occ lusa l p lane

Lowe r inc i s o rs to ma nd ibu la r p l a ne (F ig . 7 .24 ) .

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Problem

F i g .

  7 . 2 4  T r i ang le f o rm ed f r om th e l ow er pa r t o f Fas t l i gh t 's

t e t r a g o n .

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Vie wing the de n ta l c omp le x in th i s ma nn e r p rov ide s

e xc e l l e n t i n fo rma t ion on inc i s o r to rque , a nd de mons t ra t e s

tha t d i f fe re n t no rma l s ne e d to be us e d , de pe nd ing on the

underlying ske le ta l pa t te rn (Fig . 7 .25) .

Anter ior torq ue com pe nsa t io n is typica l ly necessary in

high-angle Class  1  cases, and in cases with Class II or Class III

ske le ta l bases , unless i t i s p lanned to use surgery to correc t the

skele ta l pa t te rn as part of t rea tment .

Part of the ski l l in Class II t rea tment p lanning l ies in

balancing the wish to avoid surgery agains t the unfavorable

effect on facial profile which can result from incisor torque

c o m p e n s a t i o n . H o w m u c h c o m p e n s a t i o n o f t o r q u e c a n b e

accepted before i t has to become a surgica l case?

Inc isor torq ue is con trol le d by the ac t ion of (he rec tang ular

.019 / .025 w i re in the .0 22 / .02 8 b ra c ke t s lo t s . The M B T™

bra c ke t s ys t e m ha s be e n de s igne d to re duc e the a moun t o f

wi re be nd ing ne e de d . De s p i t e th i s a dva nc e in b ra c ke t de s ign ,

whe re ne c e s s a ry the o r thod on t i s t n e e ds to a cc e p t the pos s ib l e

need to in t roduce bends in to the s tee l rec tangular wire , to add

or re duc e inc i s o r to rque , a c c o rd ing to the re qu i re me n t s o f

ind iv idua l c a s e s (C a s e DO, p . 210) .

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Class I

M i c h i g a n n o r m a l s

A r n e t t n o r m a l s

- f e m a l e / m a l e

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Class I

l o w a n g l e

176

F i g .

  7 . 2 5  V iew ing the den ta l c om p lex as

te t r agon s d i v ided i n to tw o t r i ang les p rov ides

ex c e l len t i n fo rm at ion on i nc i so r t o rq ue . D i f f e ren t

no rm a ls o r goa l s w i l l be r equ i r ed , depend ing on

s k e le ta l pa t t e rn . The m ax i l la r y and m and ibu la r

t r i ang les s how t y p i c a l an te r i o r t o rque i n v a r i ous

c l in ica l s i tuat ions . These w i l l be refer red to la ter

(p .  179) in the d iscuss ion on lower inc isor torque. I t

is im p or ta n t t o no te t ha t t hes e to rqu e

rec om m enda t ions a re f o r t he l ong ax es o f t he

inc isor te et h, as mea sured cepha lome tr ica l ly . Th is

is in cont ras t to th e torq ue va lues for th e b racket

des igns , quoted e lsewhere in th is book (p. 33) ,

which are re la t ive to the lab ia l sur faces of the

c l in ica l c rowns .

C l a s s

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Vert ical control of inc isors

In day-to-day orthodont ic prac t ice , there is a need to open

de e p a n te r io r b i t e s a nd to c lo s e a n te r io r ope n b i t e s . The

trea tment mechanics for th is were expla ined in the previous

c ha p te r . As we l l a s a t t e m pt in g to a c h ie ve a no rm a l a n te r io r

overbi te , the c l in ic ian should not lose s ight of the des i rabi l i ty

of meet ing goals for upper inc isor exposure re la t ive to the

upper l ip , as proposed by Arnet t .

  I

  lowever , i t needs to be

borne in mind tha t the surgeon has a grea ter abi l i ty than the

orthodont is t to inf luence th is aspec t of correc t ion.

Early in (Mass 11/2 t rea tment , cons iderable upper inc isor

intrus ion occurs during the leve l ing process , as progress ive ly

heavier wires are placed. Later, at the rectangular wire stage, in

Class II /2 and other t rea tments , upper inc isors can be s l ight ly

intruded, e i ther by curve in the a rchwire or by the use of ' ) '

hook he a dge a r , o r  by  a c ombina t ion o f the s e . Uppe r inc i s o rs

may be intruded relative to the lip line if the patient is

prepared to wear a ' ) ' ho ok type of headgea r (Case MP ,

p.  146), a t tached to spec ia l ly soldered hooks on the upper

s teel rec tangular w ire (Figs 7 .26 & 7.27 ) . Th e me cha nics a r e

augm ented i f the upp er a rchwire ha s 2 or 3 m m of curve of

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Spee.

An a t t e mpt ma y be ma de to e x t rude the uppe r inc i s o rs

re la t ive to the l ip l ine in the fol low ing w ay. A s tee l re c tang ular

.019/ .0 25 wire with 2 or 3 m m of ant i -Spe e curve is t ied in to

th e  lower a rch. An upper wire of .014 round s tee l i s then

placed, wi th a 3 m m pos i t ive curve of Spee . U p-a nd- do wn

anter ior e las t ics (50 gm ) can then be expected to p rod uce

s ome uppe r inc i s o r e x t rus ion .

F ig s 7 .2 6

  a n d

  7 .2 7

  Upper inc isors may be in t ruded, re la t ive to

l i p li ne , if t he pa t i e n t is p repa red to w ea r a ' J ' hook t y p e o f

headgear . C are fu l c on tou r ing o f t he m e ta l ' J ' hook s i s r equ i r ed

s o tha t t hey f o l l o w the c o n tou r o f t he c heek s.

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POSITIONING OF LOWER INCISORS IN

CLASS II CASES

Ma nag em ent of the lowe r inc isors is of ten m ore diff icult than

the upper inc isors . I t may he a cha l lenge to devise t rea tment

mec hanics which w il l achieve go od p os i t io n for the lower

inc isors , to coordina te wi th the upper inc isor PIP. for growing

individuals , growth predic t ion is not an exac t sc ience , due to

the va r i a b le d i re c t ion a nd qua n t i ty of ma nd ib u la r g row th .

Despi te th is , i t i s poss ible to adopt a logica l and sys temized

app roa ch to reach lower inc isor t re a tm ent g oals , as .set in

S ta ge 2 o f the p l a nn ing s e que nc e (p . 166) .

Contro l of the antero-poster ior pos i t ion

of lower incisors

In Class II t rea tment , the cha l lenge is normal ly to br ing the

lower inc isors suff ic iently forward to coord ina te them with

the PIP for the upp er inc isors , as de t erm ine d in Stage 1 of the

trea tment p lanning. This is t rue both in Class 11/1 t rea tment ,

and in the second phase of Class 11/2 treatment, after initial

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upper a rch a l ignment has converted the case in to e ffec t ive ly a

Class 11/1 mal occ lu s ion.

In o r thodon t i c t r e a tme n t me c ha n ic s , t he lowe r inc i s o r A /P

pos i t ion re la t ive to the upper inc isors can be changed by three

main fac tors :

1 . M ove me n t o f lowe r inc i s o rs in the ma nd ibu la r bone

(Fig. 7.28)

2.  A chan ge in the length of th e man dib le (Fig . 7 .29 )

3 .  A c ha nge in the A /P pos i t ion o f the ma n d ib le , due to

changes in the pos i t ion of the condyles in the fossae

(Fig . 7 .30) .

Fig. 7 .29

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Movement of lower inc isors in the

mandibu lar bone

The ra nge o f o r th odo n t i c too th mo ve m e n t fo r lowe r inc i s o rs

wi th in the bony h ous in g o f the m a nd ib le i s l imi t e d . M e s ia l

bod i ly mo ve m e n t o f lowe r inc i s o rs is no rm a l ly no t pos s ib l e ,

due to the a na tomy o f the bone in the lowe r inc i s o r a re a (Kg .

7 .31) . Therefore , any mes ia l movement of the lower inc isor

t ips is mainly as a resul t of a change in torque (Fig . 7 ,32) . A

rule of thumb l imit for th is proc l ina t ion is 100° to

mandibular p lane as se t in the (Mass II mandibular t r iangle

(p .  176). As these arbi t ra ry l imits a re exceeded, there comes a

perce ived r isk of ins tabi l i ty , poor es the t ics , or g ingiva l

p r o b l e m s .

Procl ina t ion of lower inc isors from the s ta r t ing pos i t ion is

norm al ly necessary in Class 11/2 cases , and ma ny th um b-

sucking Class 11/1 cases, where the lower incisors are typically

re t roc l ined. I t i s accepted prac t ice to move the lower inc isors

mesially in such cases. In (Mass 11/1 cases with Class

  11

 skeletal

bases , i t i s becoming more acceptable to proc l ine lower

inc i s o rs be yond the t r a d i t iona l 95° to ma nd ibu la r p l a ne a nd

+2  m m t o A P o . C o n v e n t i o n a l o r t h o d o n t i c t h i n k i n g w a s

The re fo re , mode s t p roc l ina t ion ma y be us e d to b r ing lowe r

inc isors in to an acceptab le re la t ion ship with PIP for up pe r

inc isors . Sl ight proc l ina t ion of lower inc isors may be

acceptable for some Class 11/1 cases with a mild Class II

ske le ta l pa t te rn . In th is way, over-re t rac t ion of upper inc isors ,

w i th c ons e que n t lo s s o f uppe r l i p c onc a v i ty ( l e a d ing to poor

fac ia l profi le ) may be avoided.

In Class II t rea tm ent th e reason able l im it to lower in c isor

p roc l ina t ion i s 100° to the ma nd ibu la r p l a ne , i n mos t c a s e s .

Accordingly, in many (Mass II cases the lower incisors can be

p roc l ine d fo rwa rds .

Ge ome t r i c a l ly , e ve r )' 2 .5° o f p roc l in a t ion mov e s the lowe r

inc isor inc isa l edges forward by 1 m m (resul t in g in space

ga ins o f 2 m m for e ve n ' 2 .5° o f p roc l ina t ion ) . C on s e qu e n t ly ,

because of this space gain in (Mass  11 t re a tme n t , l owe r

p re mola r e x t ra c t ions a re no t no rma l ly ne e de d .

The -6° torque fea ture in the MBT™ lower inc isor bracket

is he lpful in prevent ing excess ive lower inc isor proc l ina t ion. A

well -a l igned lower a rch with a .019/ .025 s tee l rec tangular wire

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agains t th is , because of the r isk of g ingiva l recess ion and

relapse.

  I

  lowever , g ingival recess ion or per iod on ta l

d i s a dva n ta ge ha s be e n s hown no t to oc c u r

1 2 1 3

  and re lapse can

be c on t ro l l e d w i th bo nde d re t a ine rs .

t ied in p lace can therefore of ten be used to sup por t Class IK

elas t ics for upper inc isor re t rac t ion, i f the case needs th is .

F i g .  7 .3 1  The range o f mo vem ent o f lower inc isors w i th in th e

bony hous ing is l im i te d .

F i g .

  7 .32 Mes ia l mo vem ent o f low er inc isors is main ly due to

p roc l ina t ion , w i th a change o f to rque .

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Favorable change in the length or

pos i t ion o f the mand ib le

Lower incisor mesial movement, relative lo upper incisor PIP,

will be augmented if there is a favorable change in the length

of the mandible and hence a mesial change in 'B' point. This

greatly assists treatment mechanics and in most cases

enhances the facial profile of the result. Also, less lower

incisor proclination will be needed if'B' point moves forward

during treatment.

An increase in mandibular length is therefore desirable for

most Class II cases, but it is questionable whether there is any

procedure which the orthodontist can follow which will

achieve this. It is a large topic, but it may briefly be discussed

under the following headings:

Mand ibu la r g row th

At the treatment planning stage for a growing individual, it is

necessary to estimate the likely quantity and direction of

mandibular growth, and hence projected changes in 'B' point.

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Generally low-angle cases show more favorable ch ange in 'B'

point than average-angle or high-angle cases (Fig. 7.33). More

favorable late mandibular growth can be expected in growing

boys than in girls.

14

Low MM angle

\ \

uu

High MM angle

\

F i g .

  7 .33 I t is necessary to make an in fo rm ed es t ima te o f the qua n t i t y and d i rec t ion o f m and ibu la r g ro w t h in a g ro w in g ind iv idua l

a t the t rea tmen t p lann ing s tage .

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Augmenta t ion o f mand ibu lar pos i t ion

wi th funct ional appl iances?

The use of a functional appliance in the mixed dentition often

produces a substantial and pleasing change for a young

patient with a Class II malocclusion, with consequent

improvement in the facial appearance. The reason for this

pleasing change is that functional appliances have the

potential to produce dental and skeletal change. They have

the potential to procline lower incisors, retrocline upper

incisors, favorably modify mandibular growth, and restrict

maxillary grow th.

Over the years, there has been much discussion and

research to establish whether functional appliances can

consistently increase the final length of the mandible, beyond

what it would have been without the functional appliance.

This is a difficult topic to investigate, and at present the

research evidence does not confirm that it is possible to

modify the quantity of mandibular growth using functional

appliances.

Despite this, many orthodontists feel that functional

appliances have a useful place in the management of Class

Favorable condy lar repos i t ioning of the

mandib le

In a few cases, the mandible may be positioned distally at the

start of treatment, and then the condyles can be expected to

reposition more mesially into a centered position, as

treatmen t progresses. For exam ple, in some Class II/2

treatments, there is the chance of

 a

  small but favorable mesial

movement of  'B'  point after the case has been converted to a

Class II/l malocclusion (Fig. 7.34), although this is difficult

to confirm with research evidence (Case DO, p. 212).

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11/1 malocclusions, because they produce a substantial early

improvement for the patient (Case'FS, p. 198), and can

reduce the amount of treatment needed in the fixed appliance

phase.

In 1998, Pancherz et al

15

  investigated 98 Class II/l

malocclusions treated with the Herbst appliance, to assess

'effective condylar growth'. This term was used to describe the

summation of the condylar remodeling, glenoid fossa

remodeling, and condylar repositioning changes. In

individuals with anterior mandibular autorotalion, they

found relatively more forward change in chin position. In

individuals with posterior m andib ular au torotation, they

found relatively more backw ard chang e in chin position.

In practical terms, if a  functional appliance is to be used in

a case, it is helpful to use it in the late m ixed de ntit ion . Al this

time, there is plenty of growth available, and it is possible to

move straight into the fixed appliance p hase , as the functional

appliance phase ends. If the functional appliance is

introduced in the early mixed dentition, it can be difficult and

time consum ing to man age the inevitable retention phase

before fixed appliances can be placed.

Some functional a ppliance effects may accrue during the

use of Class II elastics in a fully bracketed fixed appliance

case. For example, this 'functional effect' is frequently seen

when Class II elastics are used in the second phase of

 a

Class 11/2 treatment in a growing individual.

F i g .  7.3 4 Du rin g the o pe ni ng stages of some Class 11/2

t r ea tm e n ts , t he re is a pos s ib l i ty o f f av o rab le m es ia l m ov e m e nt

of 'B ' po int .

Orthopedic ver t ica l contro l of the

maxi l la?

Although this is discussed as a me thod of achieving mesial

movement of 'B '  point, there seems to be little evidence that

this is a useful orthodontic treatment procedure. It is difficult

to achieve vertical control of the maxilla orthodontically.

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Unfavo rable condy lar changes, caus ing a

reduct ion in the length of the mandib le

Effective shortening of the mandible can occur in some cases,

due to changes in the condylar regions of the mandible (Fig.

7.35). In some instances, this will be identified as being due

to idiopathic condylar reso rption. This cond ition is

fortunately rare, but can result in unfavorable downwards and

backwards movement of'B' point in response to changes in

the condylar region. It is predo mina ntly seen in female

patients

16

  (Fig. 7.36).

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F i g .

  7 .35 Id iopath ic condy lar re sorp t ion occurs ma in ly in females . I t is no t we l l unde rs to od, and fo r tu na te l y is ra re . I t can be

u n i l a t e r a l .

  I t causes a reduct ion in the length o f the mand ib le , and th is in tu rn resu l ts in an increase in over je t and anter io r open

bi te .

182

F i g .

  7 .36 Id iopath ic condy lar res orp t ion is fo r t una te ly se ldom seen, and is d i f f icu l t to ma nage . It can resu l t in un fa vorab le

do w n w a rd and backw ard movem en t o f 'B ' po in t du r ing o r a f te r o r tho don t i c t rea tm en t .

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Unfavorable condylar reposit ioning of

the mandible

During initial leveling and aligning of some Class 11/1

malocclusions, the condyles may reposition distally, giving a

substantial and unfavorable change in 'B' poin t. This results

from a situation where centric occlusion and centric relation

are not coincidental at th e start of treatm ent (Fig. 7.37 ).

Roth

17

 has advocated the early use of an acrylic splint to

identify these individuals and establish true mandibular

position before commencing treatment.

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F i g . 7 .3 7  I f c e n t r i c o c c l u s i o n a n d c e n t r i c r e l a t i o n a r e n o t c o i n c i d e n t a l a t t h e s t a r t o f t r e a t m e n t , t h e c o n d y l e s w i l l n o r m a l l y r e p o s i t i o n

d i st a ll y d u r i n g l e v e l i n g a n d a l i g n i n g . T h i s g i v e s a s u b s t a n t i a l a n d u n f a v o r a b l e c h a n g e i n ' B ' p o i n t p o s i t i o n .

REFERENCES

1 Tw eed C H 1966 Cl in ica l o r thod ont i cs . Mosby , St Lou is

2 A rne t t G W, Ja l i c J S, Kim J e t a l 1999 Sof t t i ssue ce pha lo me tr ic

a na lys is : d i a g n o s is a n d t r e a tm e n t p l a n n i n g o f d e n to fa c i a l d e fo r m i t y .

Am e r i ca n Jo u r n a l o f Or th o d o n t i cs a n d De n to fa c i a l Or th o p e d i cs

116:239-253

3 Arne t t G W, B ergma n R T 1993 Fac ia l keys to o r t ho do nt ic d iagnos is

a n d t r e a tm e n t p l a n n i n g - p a r t I . Am e r i ca n Jo u r n a l o f Or th o d o n t i cs

and Dento fac ia l Or tho ped ics 103 :299-312

4 A rne t t , G W, B ergma n R T 1993 Fac ial keys to o r th odo nt i c d iagnos is

a n d t r e a tm e n t p l a n n i n g - p a r t I I . Am e r i ca n Jo u r n a l o f Or th o d o n t i cs

and Dento fac ia l Or thope d ics 1 03 :395-411

5 Be n n e t t J , M cL a u g h l i n R P 19 9 7 Or th o d o n t i c m a n a g e m e n t o f t h e

d e n t i t i o n w i th th e p r e a d j u s te d a p p l i a n ce . I sis M e d i ca l M e d i a , Ox fo r d

(ISBN 1 899066 91 8 ) pp . 233-25 0 . Re pub l ished in 2002 by Mosb y,

Ed inburgh ( ISBN 07234 32651)

6 Giane lly AA 1998 Dis ta l mo vem en t o f the maxi l la ry mo la rs . Am er ica n

Journa l o f Or thod ont ics and Dento fa c ia l Or thope d ics 114 :66-72

7 Graber T M 1969 Max i l la ry second mo la r ext ra ct ion in C lass II

m a l occ lu s io n . Am e r i ca n Jo u r n a l o f Or th o d o n t i cs 5 6 :3 3 1 - 3 5 3

8 Bishara S E, O rth o D, Bu rkey P

 S

 1986 Second mo la r ex t ract ions: a

r e vi ew . Am e r i ca n Jo u r n a l o f O r th o d o n t i cs a n d De n to fa c i a l

Or thoped ics 89 :415-424

9 Wi lson W L , Wi lson R C 1981 Mo du la r o r t hod ont ics m anu a l . De nver :

Rocky M o u n ta i n Or th o d o n t i cs

10 Basdra E K, Stc l l z ig A, Kompo sch G 1996 Extrac t ion o f max i l la ry

second mo la rs in th e t rea tm en t o f C lass I I ma loc c lus ion . A ng le

Or th o d o n t i s t 6 6 ( 4 ) :2 8 7 - 2 9 2

11 Fa st lgh t J 2000 Te tra gon : a v isua l cepha lom etr ic ana lys is . Jou rna l o f

C l i n ica l Or th o d o n t i cs 3 4 ( 6 ) :3 5 3 -3 6 0

12 Ar tun J , Os te rbe rg S K, Kok ich V G 1986 Long- t e rm e f f ect o f th i n

i n te r d e n ta l a l ve ol a r b o n e o n p e r i o d o n ta l h e a l th a f te r o r th o d o n t i c

t r e a t m e n t . Jo u r n a l o f Pe r i o d o n to l o g y 5 7 :3 4 1 - 3 4 6

13 Ruf S, Hansen K, Pancherz H 1998 Does o r t ho don t ic p roc l ina t ion o f

lower inc iso rs in ch i ld ren and ado lescen ts cause g ing iva l recess ion?

Am e r i ca n Jo u r n a l o f Or th o d o n t i cs a n d De n to fa c i a l Or th o p e d i cs

114:100-106

14 Rio lo M e t a l 1974 At las o f c ran io fac ia l g ro w th . Cente r fo r Hu ma n

Gr o w th a n d De ve l o p m e n t , Un i ve r s i t y o f M i ch i g a n

1 5 Pa n ch e r z H , Ru f S , Ko h l a s P 19 9 8 'E f fe c t ive co n d y l a r g r o w th ' a n d c h i n

p o s i t i o n ch a n g e s i n He r b s t t r e a tm e n t : a ce p h a l o m e t r i c

r o e n tg e n o g r a p h i c l o n g - te r m s tu d y . Am e r i ca n Jo u r n a l o f O r th o d o n t i cs

a n d De n to fa c i a l Or th o p e d i cs 1 1 4 :4 3 7 - 4 4 6

1 6 W o l fo r d L M , Ca r d e n a s K 1 9 9 9 Id i o p a th i c co n d y l a r r e so r p t i o n :

d i a g n o s is , t r e a t m e n t p r o to co l a n d o u tco m e s . Am e r i ca n Jo u r n a l o f

Or th o d o n t i cs a n d De n to fa c i a l Or th o p e d i cs 1 1 6 :6 6 7- 6 7 7

1 7 Ro th R 1 9 7 2 Gn a th o l o g i ca l co n ce p ts a n d o r th o d o n t i c t r e a tm e n t

goa ls . In : Ja rabak J R, F izze l l, J A (eds) Tec hn ique and t r ea tm en t w i t h

l igh t w i re app l iances, 2nd edn . Mosby, St Lou is pp . 1160-1223

sca n n e d b y UST te a m

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CASE

An adull female patient, aged 23.1 years at start of

treatment. The skeletal pattern was slightly Class II

(ANB 5°) and low angle (MM 20°)

F i g .

  7 .3 8

The buccal occlusion was Class II bilaterally, with a deep bite

and upper incisor crowding and rotations. All permanent

teeth were present, including unerupted third molars. The

possibility of

 a

 combined orthodontic/orthogna thic surgical

approach was discussed with the patient, but she wished to

avoid surgery. Accordingly, a decision was made to extract all

the third molars and the upper first premolars, and treat the

case to a Class II buccal occlusion.

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F ig .

  7 .41

F i g .  7 .4 4

All the teeth were banded or bracketed except the lower

incisors. Lower incisor separation and enamel reduction were

carried out.

184

F i g .

  7 .47

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L.J. Beginning

23.1 years

6/21/96

Fig.

 7.39

S N A   /  8 2

S N B /

A N B /

A N

  FH

P o - N  FH

W I T S

GoGnSN

F M

7 7

5

3

0

3

3 0

2 0

M M

 / 2 0

1  t o A - P o

1 t o A - P o

6

0

t o

 Max

  P l a n e / 1 1 1

t o M a n d P l a n e / 9 8

m m

m m

m m

m m

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Fig.

 7.45

Fig. 7.46

185

Fig. 7.48

Fig. 7.49

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After 2 months of treatment, upper and lower rectangular

.017/.025 HANT wires are in place, with upper lacebacks to

the canines. A lower right laceback is in place to assist with

midline correction.

F i g .

 7.50

After

  5

  m o n t h s

  of

 t re a tm e n t , l ow e r fi rs t m o la r ba nd s we re

re pos i t ione d . Uppe r

  and

  lowe r re c t a ngu la r H ANT wi res

 are in

p la c e ,

  and

  la c e ba c ks ha ve be e n d i s c on t inue d .

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After  8  m o n t h s  of  t re a tme n t , no rm a l up pe r s t ee l r e c t a ngu la r

wires were placed, wi th pass ive l iebacks

 in the

 up pe r a rc h .

Passive tiebacks (Figs 7.59 and 7.61 ) are  norma l ly p l a c e d  for

be twe e n fou r and six week s . Act ive t iebacks (Figs 7 .58, 7,62,

7 . 6 4 )  may t h e n  be us e d  to  a c h ie ve s pa c e c los u re  an d  overjet

re duc t ion .

186

F i g .

 7.59

scanned by LIST team

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. >

F ig .

  7 .60

F i g .

  7 .61

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7 3

One year into treatment, and upper space closure with torque

control is being achieved with active tiebacks and a steel

rectangular wire.

After 15 mo nths of treatment, uppe r space closure was almost

complete.

F i g .

  7 .62

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188

Norm al settling procedures were followed, and the case is

seen here after 20 months of treatment.

The case after one month of settling.

Fig. 7.65

F i g .  7 .68

F i g .

  7 .7 1

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F i g .

  7 .63

F i g .

  7 .64

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Fig. 7 .66

F i g .

  7 .67

F i g .

  7 .72

F i g .

  7 .73

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The case after appliance removal.

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2H

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Fig.

  7.77

The facial profile shows pleasing balance and harmony.

Predictably, there was little cephalometric change during the

treatment period. The active treatment t ime was 21 months.

Fig.

  7.80

190

S N a t S

L . J . B e g i n

L . J . F i n a l

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Fig .  7.78

Fig .

  7.79

L.J Final

2 5 . 0 y e a r s

5 (26 /98

Fig.

  7.81

S N A

S N B

A N B

A-N FH

Po-N FH

W I TS

GoGnSN

F M

M M

1 to A-Po

1 t o A - P o

1 t o M a x P l a n e '

1 t o Ma nd P lane

' 8 1

' 7 6

'  4

1

• 4

3

' 3 1

2 1

2 2

3

0

1 0 2

9 9

m m

m m

m m

m m

m m

Fig .  7.82

P a l a t a l P l a n e &

P a l a t e C u r v a t u r e

L.J.Final

L.J.Final

Fig.  7.84

M a n d .

  S y m p h a s i s

& M a n d . P l a n e

L.J.Begin

L.J.Final

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CASE TC

Male patient, aged

  11.4 years, with a Class I skeletal

relationship (ANB 3") and

  a

  slightly low-angle pattern

(MM 23°). He was slightly Class II dentally. This

  type of

malocclusion is frequently seen.

The incisor relationship was close to normal, although there

was a midline discrepancy of 2 mm and a lack of space for

erupting upper canines. The molar relationship was 3 mm

Class II on the right and 2 mm Class II on the left. It was

decided to treat to a square arch form.

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F i g .

  7 .89

Radiographs showed all permanent teeth developing

normally.

F i g .

  7 .92

At the start of treatment, the first molars were banded, and

the patient was asked to wear a sleeping headgear. The lower

arch was fully bracketed, and leveling and aligning was

commenced with a .016

 I

 [ANT wire. An upper sectional

multistrand wire was placed for the upper incisors.

F i g .

  7 .95

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T.C.Beginning

11.4 years

3/6/97

SN A / 85 •

S N B / 8 2 '

A N B  3 °

A -N

  FH 0 mm

P o - N  FH 0 mm

W I T S  1 mm

G o G n S N  /

  2 6

 °

F M /  2 0 

M M / 2 3 '

J L

  t o

  A -Po

  4 mm

1

  to

 A -Po

  0 mm

1  to M ax P l a n e / 11 8 °

1

  to

 M a n d P l a n e /

  92 *

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F i g .

  7.90

F i g .  7.91

F i g .

  7.96

F i g .

  7.97

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Occlusal views at the start of trea tmen t.

F i g .

  7 .98

Sequential views after 2 months, 4 months, and 9 months of

treatment. An upper sliding jig was placed on a .020 round

archwire, and Class IJ elastics were worn during the daytime,

with a headgear at night (Fig. 7.102). Upper molars and

premolars moved distally to a Class I relationship, and space

was created for upper canines (Fig. 7.103).

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F i g .  7 . 1 0 1

Occlusal views after 9 months of treatment. A lower lingual

arch was maintained to support lower molars so that mesial

mo vem ent did no t occur in response to the Class II elastics. A

lower steel rectangular wire was in place, with passive

tiebacks.

After 18 months of treatment, the case is seen with upper and

lower rectangular steel w ires, passive lower tiebacks, and

active upper tiebacks. Additional torque frequently needs to

be placed in the anterior part of the upper archwire at this

stage, to achieve palatal root torque of upper incisors and to

correct the buccal occlusion (p. 284).

194

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F i g .  7 .99

HG at n ight

F i g .  7 .100

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F i g .  7 .102

F i g .

  7 .105

F i g .  7 .106

F i g .  7 .108

F i g .

  7 .109

www.allislam.net

The case af te r appl iance removal .

Fig.  7.110

Occlusa l v iews of the case af te r t rea tmeni . Subsequent

de ve lopme n t o f th i rd mo la r s wa s mon i to re d .

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Fig.

  7.113

fac ia l es the t ics sho we d pleas ing ba lan ce and h ar m on y a t the

end of t rea tment , wi th upper and lower inc isors wel l

pos i t ioned in the fac ia l complex.

F ig . 7 .116

scanned by LIST team

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'

F i g .

  7.111

F i g .

  7.112

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F i g .

  7.114

F i g .

  7.115

T.C.FINAL

13.11 years

10 /6 /99

F i g .

  7.117

S N A

S N B

A N B

A -N   FH

Po-N  FH

W I T S

G o G n S N

F M

M M

1 t o A -Po

1 t o A -Po

t o

 Max

  P lane

t o M a n d P l a n e /

8 6 °

8 4 °

2 °

0  mm

3  mm

0  mm

2 8

 °

2 4 °

' 2 7 °

5

  mm

1  mm

1 1 8 °

8 9 °

scanned by UST team

w w w . a l l i s l am. ne t

CASE TS

A female patien t, aged T4.0 years, with (Mass II dental bases

(ANB 7°) and a Class II facial profile.

fife

■ jHP**w

Kk

I

^m

: '

0

F i g .

  7 .1 1 9

Dentally, the patient showed a typical Class II division l

malocclusion, with slightly retioclined lower incisors, and an

increased overjet. Molar relationship was a full unit (Mass II

on the right side and half

 a

  unit Class II on the left side.

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Fig. 7 .122

Occlusally, the patient vyas assessed as havin g an ovoid arch

form. There was a small amount of crowding amongst the

lower incisors. The radiog raph s confirmed that third mo lars

were developing, and were of good size and position.

A

  decision was made to commence correction on a non-

extraction basis, using a twin block appliance. The patient and

parents were informed that consideration might  need  to be

given to the extraction of upper second molars and lower

third molars as treatment progressed.

Fig. 7 .125

At the start of treatment, upper and lower twin block*

appliances were placed for full-time wear.

REFERENCE

"C lark W J 1988 The t w in b loc k t ec hn ique : a f unc t i ona l o r t ho ped i c

app l i anc e s y s t em. Am er i c an J ou rna l o f O r t h odon t i c s 93 : 1 -18 .

s c anned by L I ST t eam

www.allislam.net 

>

S N A 7 8

SNB / 71

A N B /

  7

A N F H

Po-N FH

W I T S

G o G n S N

F M

M M

1 t o A-Po

1 t o A - P o

1

-5

9

3 8

2 5

3 2

9

0

1 t o M a x P l a n e / 1 1 1

1 t o M a n d P l a n e / 9 1

m m

m m

m m

'

'

'

m m

m m

0

0

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F i g .

  7 .1 2 3

F i g .  7 .1 2 4

F i g .

  7 .1 2 6

F i g .

  7 .127

Fig . 7 .129

F i g .

  7 .130

scanned by LIST team

www.allislam.net

O

<

m

71

<

o

Occlusal view of the twin block appliances. These were

designed by Dr Bill Clark.

F i g .

  7 .1 3 1

The patient showed good cooperation with the twin block

appliances and these views show the dentition 16 months

from the start of treatment. The overjet was fully reduced, and

a typical lateral open bite had developed.

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F i g .

  7 .134

F i g .  7 .1 3 7

scanned by LIST team

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Clark WJ 1995 Twin block

functional therapy: applications

in dentofacial orthopedics.

Mosby W olfe (ISBN 0723 42120X).

New edition due in 2002.

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F i g .

  7 .1 3 5

F i g .  7 .1 3 6

F i g .

  7 .1 3 8

F i g .  7 .1 3 9

scanned by LIST team

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Facial photogra phs after 16 mon ths of treatment, together

with progress tracings.

F i g .

  7 .1 4 0

SN a t S

T . S . B e g i n

T . S .

  P r o g r e s s

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After 16 months, the twin block appliances were

discontinued, and upper and lower fixed appliances were

placed. Here, the right side progress is shown 1 month, 3

months, and 8 months after placement of the fixed

appliances. Some enamel reduction was carried out among

the lower incisors early in the fixed appliance phase. .016

HANT wires were followed by rectangular HANT wires and

then steel rectangular working wires. Light Class II elastics

were used to maintain the overjet correction.

F i g .

  7 .1 4 6

Fixed appliances were in place for a total of 12 months. Here,

the case is seen 10 month s into fixed appliances, during the

typical settling phase.

F i g .

  7 .1 4 9

scanned by LIST team

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T.S.Progress

14.11 years

6/20/97

Fig.  7.141

SNA/ 78°

S N B / 7 4 °

AN B 4°

A N F H 0 m m

Po-N FH 0 m m

W I T S 2 m m

G o G n S N 4 0 °

F M /

  27°

M M /  33°

1 to A-Po 6 mm

1 to A-Po 4 mm

1 t o Max P lane 106°

1 t o Ma nd P lane 98°

Fig.  7.142

P a l a t a l P l a n e &

P a l a t e C u r v a t u r e

T.S.Begin

T . S . P r o g r e s s

M a n d .  S y m p h a s i s

& M a n d . P l a n e

T.S.Begin

T . S . P r o g r e s s

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Fig.  7.147

Fig.  7.148

Fig.  7.150

Fig.  7.151

scanned by LIST team

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The case after removal of the fixed appliances.

- •

^ - ^ ^ . . ,

F i g .

  7 .152

Good progress had been made. Extractions were discussed

during treatment planning, but it proved possible to manage

the case on a non-extraction basis. It was finished to an ovoid

arch form.

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F i g .

  7 .155

A

  pleasing improvement in facial esthetics was achieved, and

Figure 7.158 com pares before and after profiles. The ANB

angle changed from 7° to 3° during the treatment period

(Fig. 7.2, p. 164).

F i g .

  7 .158

Cephalometric superimpositions show that favorable

downward and forward mandibular growth had occurred

during treatment, mainly during the twin block phase.

F i g .

  7 .161

scanned by LIST team

SN a t S

T . S .

 B e g i n

T . S . F in a l

www.allislam.net 

F i g .

  7 .153

F i g .

  7 .154

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F i g .

  7 .156

F i g .

  7 .157

T.S.Final

16.0 years

6/30/98

F i g .

  7 .159

SNA / 78 •

S N B

A N B

A N F H

Po-N FH

W I TS

7 5 °

3 °

3 m m

3 m m

3 m m

G o Gn SN / 4 3 °

F M

28 "

M M / 3 6 '

1 t o A - P o

1 t o A -Po

7 m m

4 m m

1 t o M a x P l a n e / 1 1 1 •

1 t o M a n d P l a n e / 9 3 "

F i g .

  7 .160

P a l a t a l P l a n e &

P a l a t e C u r v a t u r e

T . S . B e g i n

T .S .F i na l

F i g .

  7 .1 6 2

F i g .  7 .163

scanned by LIST team

M a n d . S y m p h a s i s

& M a n d . P l a n e

T . S . B e g i n

T .S .F i na l

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CASE DO

An adul t female pa t ient , aged 19.11 years , wi th Class I

de n ta l ba s e s (ANB 3° ) a nd a s l igh t ly low-a ng le pa t t e rn

(MM

  2 3 ° ) .

  Uppe r inc i s o r s we r e re t roc l ine d a t 97° to th e

ma x i l l a ry p l a ne , a nd lowe r inc i s o rs we re re t roc l ine d a t 84

c

t o t h e m a n d i b u l a r p l a n e .

The patient presented with a typical Class II division 2

malocc lus ion. The m ola r re la t io nshi p was 1 m m Class II on

the left and 5 m m Class II on the rig ht side. Th ere wa s an

associa ted midl ine discrepancy of 3 mm.

Fig. 7 .164

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The lower le f t second molar had been a source of chronic

seps is , and was cons idered to have a very poor prognos is . A

decis ion was made to extrac t th is tooth , toge ther wi th the

upper second molars and the lower r ight th i rd molar .

The upp er lef t secon d mo lar was extrac ted to ba la nce the

loss of the lower le f t second molar . The upper r ight second

molar was extrac ted to ass is t t rea tment mechanics , to achieve

a Class I re la t ionship .

Fig. 7 .167

F i g .  7 . 1 7 0

scanned by LIST team

www.allislam.net 

Fig.

  7.165

D.O.Beginning

19.11 years

7/8/96

r-iC— ^———-

/

  Cl

/~S V

IGX  \

Fig.

  7.166

j \

I

 

(

v_

V\  s  r

r/

  ri

4,

^ k

Nl\

?

  s

i \ \

SNA

SNB

ANB

A-N

  FH

V

  Po-N FH

\ WITS

\ GoGnSN

)  FM

^

  MM

1  to  A-Po

1

  to

 A-Po

1

  to Max

 Plane

1  to  Mand Plane.

8 3 °

80

  '

3

 °

2

  mm

1

  mm

0  mm

2 9 °

20°

23°

0  mm

■ 2

  mm

97

 •

8 4 °

»J

>

o

<

m

3

<

m

o

n

n

-1

33

m

>

H

rn

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Fig .

  7.172

Fig.  7.171

207

scanned by LIST team

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*

>

O

<

m

73

<

o

n

r~

>

1/1

1/1

73

m

>

m

2

At the start of treatment, all molars were banded and brackets

were bonded on the remaining teeth. Additionally, an upper

acrylic removable bite plate was provided for full-time wear.

The open ing upper arch wire was .0175 multistrand, with a

bend in the upper left central incisor region to reduce force.

This was replaced 1 month later by a .016 HANTwire. During

the first 2 months, a .016 HANTwire was used in the lower

arch. The lower left first molar band was repositioned at the

second adjustment visit.

F i g .

  7 . 1 7 3

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Sequential views of the right side occlusion  2  months , 3

months, and 7 months into treatment. At 2 months, upper

and lower rectangular HANT wires were placed, and the bite

plate was discontinued. After 7 months, upper and lower

rectangular steel wires were placed to complete correction of

the overbite (p. 111).

Occlusal views of the case after 8 months of treatment. The

patient was asked to wear full-time light Class II elastics to

assist bite opening.

F i g .  7 .176

208

F i g .

  7 .182

scanned by UST team

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F ig .

  7 .174

F i g .

  7 .175

»

>

O

<

m

<

O

T l

n

i

-

>

1/1

H

m

>

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F ig .

  7 .177

F ig .

  7 .180

Fig.

  7 .183

F i g .

  7 .178

F i g .

  7 .181

F i g .

  7 .184

scanned by LIST team

209

www.allislam.net

o

<

m

<

o

n

r—

>

1/1

3 3

rn

>

Reverse curves (p. 137) were added to the rectangular wires

after they had been in place for 2 months. Addition torque

was placed in the upp er incisor region to assist bite openin g.

F i g .

  7 .185

F i g .

  7 .188

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210

Settling was commen ced after 14 mo nths of treatment, an d

.016 HANT wires were used for this. A Kobayashi lie was

placed on the upper right canine, and the patient was asked to

wear right side Class II elastics as necessary to maintain the

buccal occlusion on that side and the midline correction.

A full upper .014 or .016 archwire is used when settling

som e Class II cases (p. 295 ). Such wires can be be nt back

behind molars to control the overjet.

The case after removal of fixed appliances an d I mo nth of

further settling.

F i g .

  7 .194

scanned by LIST team

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F i g .  7 . 1 9 6

www.allislam.net 

>

-z.

O

<

m

PO

<

o

-n

n

>

1/1

1/1

m

>

m

2

Occlusal views of the case after band removal and 1 month of

settling. It was agreed with the patient to monitor the

development and eruption of the three remaining third

molars.

Fig . 7 .197

A subtle but pleasing im prove me nt in the facial profile

occurred as a result of upper and lower incisors being moved

to more appropriate positions in the facial complex. During

treatment the SNA angle increased from 83° to 84° (p. 170).

SNB angle increased by 2° to 82° (p. 181).

F i g .

  7 .200

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212

www.al l is lam.net  

Problem

F i g .  7 .203

Superimpositions confirm that most of the correction was

obtained by dental change, although there was some mesial

movement of pogonion during the treatment period.

SN a t S

D . O. Beg i n

D.O. F ina l

Fig . 7 .206

scanned by LIST team

www.allislam.net

,  >

F i g .

  7 .198

F i g .  7 .1 9 9

SN A

V SN B

0 \  A N B

^ > \  A-N FH

\  Po-N FH

\  W I T S

)  G o G n S N

s~*"^  F M

[  M M

J  1 to

 A-Po

"\ 1 t o A - P o

/  1 t o Ma x P lane

(  1 t o Ma nd P lane

8 4 "

' 8 2 *

2 •

2 m m

2 m m

-3 mm

27 °

- 1 9 °

2 0  '

5 m m

2 m m

1 1 4 °

1 0 6 "

Fig.

  7.202

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Fig.  7.204 Fig .  7.205

P a l a t a l P l a n e &

P a l a t e C u r v a t u r e

D . O . B e g i n

D.O. F ina l

F i g .

  7 .207

F i g .

  7 .208

scanned by LIST team

M a n d .  S y m p h a s i s

& M a n d . P l a n e

D . O . B e g i n

D . O . F i n a l

www.allislam.net

Intraoral photographs taken 19 months after completion of

treatment show that the lower left third molar has erupted

into a less than ideal position.

A lower lingual arch from first molar to first molar was

placed, with a band on the lower left third molar. A section

archwire was used together with a separating m odule to assist

in uprighting the lower left third molar.

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Intraoral photographs after correction of the lower left third

molar.

F i g .

  7 .215

Occlusal views of the case after com plelion of the ortho don tic

treatment. Upper third molars erupted into satisfactory

position (p. 173).

F i g .

  7 .218

scanned by LIST team

.. *

www.allislam.net 

F i g .

  7 .213

F i g .  7 .2 1 4

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F i g .  7 .219

scanned by UST team

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CHAPTER 8

A n o v erv iew o f Class III t r eatm en t

In t roduc t ion 219

Accurate record- taking - displacem ents 219

Mandibu la r p rogna th i sm or maxi l l a ry

ret rognathism? 220

The t iming of Class HI t reatmen t 220

The surgical/non-surgical decision in Class III

t r ea tment 222

The posterior 'squeezing out ' effect of molar

crowding 224

Class III me chan ics 22 5

Lower inc i sor mov em en t in C las s I II cases 232

Dis tal movement and ret ract ion of the lower

inc isors wi th in the ma ndibu la r bo ne 232

Dis ta l movement o f mandibu la r bone - d i s t a l

r epos i t ion ing 233

Dis ta l movement o f mandibu la r bone - r es t r i c t ion

of growth? 233

Mesial movement of mandibular bone - Class I I I

g rowth 234

Case MS A Class I II non -ex trac t ion case wi th

c r o w d i n g 2 3 6

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The four - s tage t r ea tm ent p la nn ing p roces s 226

Setting a PIP for the up pe r incisors 226

The lower incisors 22 6

The r emain ing upp er t ee th 227

The rem ainin g lower teeth 227

PIP co m po ne nt s in C las s I II t r ea t me nt 228

Upper inc i sor movement in C las s I I I

t r ea tment 229

Mesial movement of upper incisors wi thin

the bon e 230

Limits to mesial movement of upper

incisors 230

Mesial movement of maxi l lary bone due to

growth 231

Mesial mo vem ent o f maxi ll a ry bo ne d ue to

or thodon t i c t r ea tment 231

Case KB A C las s HI case t r ea ted wi th ex t r ac t ion

of s econd mo lar s 242

217

scanned by

 UST

 team

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INTRODUCTION

The in t roduc to ry d i s c us s ion in C ha p te r  7  (p . 162) c onc e rn ing

' too th a l ignme n t ' o r thodon t i c s ve r s us ' de n tu re pos i t ion ing '

or thodont ics is re levant to Class III t rea tment . The majori ty of

C la s s I I I o r thodon t i c c a s e s re qu i re de n tu re pos i t ion ing

proce dures to achieve and then m ain ta i n a correc t inc isor

re la t ionship in the fac ia l complex. I t i s beyond the scope of

this text to d iscuss de ta i ls of the Class III p lanning process ,

bu t t he fo l lowing ge ne ra l c omme nts a nd ove rv ie w wi l l

e mpha s iz e ke y po in t s wh ic h c a n be re l a t e d to t r e a tme n t

me c ha n ic s .

Success ful t rea tment of Class III cases depends on

ide n t i fy ing the t rue na tu re o f the ma loc c lus ion , a nd on

e va lua t ing a ny p rob a b le g row th c ha nge s . The fo l lowing a re

re levant to the management of these cases :

• Ac c ura te re c o rd - t a k ing - d i s p la c e m e n t s

• M a nd ib u la r p rog na th i s m o r ma x i l l a ry re t rogna th i s m ?

• The l im ing of Class III t rea tm ent

• Ma king the correc t surgica l /non-su rgica l dec is io n

• The pos te r io r 's que e z in g ou t ' ef fe ct o f mo la r c r owd ing

• Th e use of Class III me cha nics .

Accurate record-taking - displacements

I f t he re i s a ma n d ib u la r d i s p la c e m e n t be tw e e n c e n t r i c r e l a t ion

(C R ) a nd c e n t r i c oc c lus ion (C O) , t h i s ne e ds to be ide n t i f i e d

a nd a c c u ra t e ly re c o rde d a t t he re c o rd - t a k ing a ppo in tme n t .

D i s p la c e me n t s (F ig . 8 .1 ) c a n be a ma jo r f a c to r in de te rmin ing

a surgica l versus non-surgica l dec is ion for some pa t ients .

I t i s therefore essent ia l lo take records with the condyles

centered in the fossae , so tha t t rea tment p lanning can be

ba s e d on the C R pos i t ion o f the ma nd ib le . Th i s w i l l i nvo lve

plac ing a wax bi te (Fig . 8 .2) for (he record-taking process ,

inc lud ing s tudy mode l s , f a c i a l pho tos , c e pha lome t r i c

ra d iog ra phs , a nd , fo r s ome c a s e s , t omogra ph ic ra d iog ra phs . I t

i s t he n ne c e s sa ry to ad jus t fo r t he sl igh t ma nd ibu la r op e n i ng

du r ing fa ci al a n d c e p ha lom e t r i c a na lys i s . The t rue A /P

pos i t ion o f the ma nd ib le , w i th c e n te re d c ondy le s , ne e ds to be

accura te ly es tabl ished in th is way, as a bas is for t rea tment

p l a n n i n g .

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F ig .

  8 .1 Man d ibu la r d i sp lacemen ts a re f reque n t l y fou nd in

Class II I malocclusions. They need to be identif ied and

accura te ly recorded.

F i g .

  8 .2 A wa xb i te is requ i r ed to accura te ly record the A /P

pos i t i on o f the mand ib le , w i th condy les cen te red . In th i s w ay ,

accura te t rea tment p lann ing w i l l be poss ib le , based on records

taken w i th the man d ib le a t the CR pos i t i on .

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Black = wi thi n 1 5D

Green = w i th i n 2 SD

ue = w i th in 3 SD

Red = mo re tha n 3 SD

F ig .

  8 .5 The Ar ne t t ana lysis became ava i lab le in September 1999. I t o f fe rs n ew levels o f sop h is t ica t io n as an a id in d iagnos is and

treatment p lann ing fo r o r thodont is ts and surgeons. I t emphas izes so f t t issue fac ia l measurement , and the numer ica l p r in tou ts are

color coded.

The ana lys is is re la t ed to th e t rue ver t ica l l ine (TVL) and has separa te no rms for males and females . The t re a te d p at i en t s how n here ,

by permiss ion o f Dr Arn et t , had b i -m ax i l la ry surgery to advance th e max i l la and se t back the m and ib le . There was a lso

hydroxyapet i te gra f t ing o f o rb i ta l r ims.

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The su rg i ca l /non -su rg i ca l dec i s ion i n C lass I II t r e a tm e n t

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As with Class II t rea tm ent , i t i s im po rtan t to recognize those

Class III cases which have a major ske le ta l d isproport ion,

e i ther a t the t ime of assessment , or where there is a

probabi l i ty of unfavorable growth. For such individuals , i t

wi l l be necessary to cons ider a surgica l /or thodont ic solut ion.

Tre a tme n t on the ba s i s o f o r thodon t i c s a lone s hou ld be

delayed, or d iscarded as a poss ibi l i ty .

T h e S'l'CA of Arnet t e t a l was discussed in Chap ter 7

(p .

  163). In the fol lowing theore t ica l cons idera t ion of some

aspects of Class  111  t re a tme n t , t he s a m e s e ve n m e a s u re me n t s

wil l be cons idered, for cases where i t i s assumed tha t the

upper- and mid-thirds of the fac ia l profi le a re c lose to idea l ,

and tha t the upper inc isors a re wel l pos i t ioned.

Th e theore t ica l t rea tme nt s i tua t ions , A, B, and C, expla in

the potent ia l d i ff icult ies :

S i t u a t i o n A - a s u r g i c a l /

r equ i r ed , t hen the s u rgeon \

m a les . The s u rgeon w i l l t he

r e a l i g n m e n t o f t h e m a n d i b l

op t im a l f ac ia l an d den ta l re

' ( ' )  64 1

o r t h o d o n t i c c o r r e c t i o n t o a n i d e a l r e s u l t.

v i l l no r m a l l y w a i t un t i l a l l g ro w th has f in is

i r e q u i r e t h e o r t h o d o n t i s t t o d e c o m p e n s a u

e a n d / o r m a x i l l a , w i t h t r a n sv e rs e c o r r e c t i o r

su l t (F ig . 8 .6) .

TVL

. 4 i  i  "  \  \

I f i t i s d e t e r m i n e d t h a t m a n d i b u l a r s u r g e ry w i l l b e

h e d ,  w h i c h m ay be as l a te as 22 y ears o f age i n

' t he i nc i s o r s . C or rec t i on w i l l be ac h iev ed by A /P

o f t he m a x i l l a i f nec es s ary . Th i s s h ou ld l ead to a n

TVL

0

1

  Color codes used wi th

the Arne t t sof t t issue

cephalometric analysis

•  2

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1 •' '

  ' '

T

  3

  < v  J  j

Black  = w i t h i n  1 SD ■ ■

_5 Green =  w i t h i n  2 SD

Blue  = w i th in 3 SD

Red   =  more than 3 SD  ■ ■

-3

F i g .

  8 .6 I f a c om b ined s u rg ic a l and o r th odo n t i c s o lu t i on is us ed to t r e a t t h i s case , a c los e - to - idea l f ac ia l p ro f i l e a nd den ta l

outc om e should be poss ib le . A 6-mm m an dib ula r set -back w i l l resul t in mea surem ents to t rue ver t ica l line (TVL) wh ich are w i th in

1 SD of the ideal .

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Situation B - o rtho don tic m asking of a mild Class III skeletal case. As an alternative to 'A' above, if the underlying

skeletal discrepancy is mild, it may be decided to follow a treatm ent pla n based o n orth od onti cs alone . This will allow

correction to be commenced much earlier, and the patient will be informed of the possibility of late mandibular growth.

The orthodontist will then solve the problem by 'masking' the underlying Class

 111

  discrepancy by dental compensation.

This will involve proclination of upper incisors and/or retrocHnation of lower incisors. Good patient cooperation with Class

III elastics and/or a face mask will normally be needed in this type of treatment. This should lead to an acceptable dental

and facial outcome without the need for orthognathic surgery, which patients wish to avoid (Fig. 8.7).

TVL

TVL

Black = wit hin  1  SD

Green = within 2 SD

Blue = within 3

 SD

Red = more than 3 SD

F i g .

  8 .7 In th is m i ld C lass I II case, a t re atm en t p lan can be based on or t ho do nt i c to ot h mov eme nts to mask the s l igh t

under l y i ng s k e le ta l d i s crepancy . Th is c an l ead to a go od den ta l ou t c om e, and s om e ' im pro v em ent i n f ac ia l p ro f i l e m eas urem ents .

In th is theoret ica l representat ion, the upper inc isors were proc l ined 2° and the lowers were ret roc l ined 8° .

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Situation C - late mandibular growth.

  After orthodontic masking of a  mild Class III malocclusion, late mandibular

growth can occur, especially in males. This is a difficult situation to manage. Sometimes the patient will find the late change

in dental and facial outcome acceptable, and seek no further treatment. However, if mandibular surgeiy is deemed

necessary, there is limited scope for facial improvement from the surgery, because of the dentally compensated teeth

(Fig. 8.8). The incisors will need to be decompensated by orthodontics before surgery, if there is to be an optimal facial

benefit from the surgery.

TVL

TVL

Black = w i t h in   1  SD

Green = wi th in 2 SD

Blue = wit h in 3 SD

Red = more tha n 3 SD

F i g .

  8 .8 In some cases, la te mand ibula r gr ow th occurs af ter th e type of t rea tm en t show n in 'B ' abov e. This is d i f f i cu l t t o

mana ge. If a dec is ion is mad e to car ry ou t man dibu lar surgery , i t is o f t en necessary to pro v ide fu r th er o r tho do nt ic t re am en t to

decom pensa te th e inc isors , be fore the su rgery .

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T h e p o s te r i o r ' s q u e e z i n g o u t ' e f f e c t o f

m o l a r c r o w d i n g

There ha s been discussion of posterior crow ding as a factor in

the development of Class III malocclusions. 'The theory

suggests that a squeezing out effect can occur because of

crowding in the molar regions, which can contribute to an

anterior open-bile malocclusion in a mandible with poor

vertical growth in the ramus area (Fig. 8.9). Alternatively,

good ramus growth can lead to a Class

 111

 malocclusion.

This concept is not well understood, and has not been fully

investigated. However, some carefully selected Class III cases

4

(see Case KB, p. 242) and some open-bite cases

5

  respond well

to a treatment approach involving second molar extractions.

This suggests som e validity to the theory of a squeezing out

effect. It may be an important etiological factor in some cases.

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F i g .

  8 .9 Poster io r c ro wd ing has been d iscussed as a fac t or in the d eve lopm ent o f some C lass I II ma locc lus ions and an ter io r o pe n b i te

malocc lus ions. Poster io r ' squeez ing ou t e f fec t ' can be re l ieved by ex t ra c t ion o f second perm anen t molars in se lec ted cases, wh ich is

he lp fu l to t rea tmen t mechan ics .

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wmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmammmmm

Class III mechanics

Inter-maxillaiy Class 111  elastics (Fig. 8.10) are most helpful in

orthodontic (non-surgical) correction of Class III cases. They

tend to produce lower incisor retroclination, upper incisor

proclination, and A/I' correction of the molar relationship

(Fig. 8.11). All components of the Class III elastic force can

therefore be helpful in reaching treatment goals in average or

low angle cases. With Class II elastics (Fig. 8.12) the vertical

components may be perceived as disadvantageous in higher

angle cases.

F i g .

  8 .10

  In term ax i l lary Class

  III

  elastics.

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F i g .

  8.11

  Th is shows the forc e vec tors invo lve d in the use of

  F i g . 8 . 1 2

  Th is shows the fo rce vec tors invo lved in the use of

Class I II elast ics. In low an gle d eep b ite cases al l fo ur vecto rs are Class I I elast ics. In lo w an gle Class I I cases al l fou r vectors are

helpfu l . Howe ver , in h igh angle Class I II cases w i th an op en b i t e he lpfu l . (The ver t ica l com po ne nt in th e upper inc isor reg io n is

tendency , upp er molar ex t rus io n is cont ra- ind icate d. This can be balanced by curve of Spee in the up per archw ire, and hence

counterac ted w i t h a pa lata l bar (F ig . 5 .29, p . 107) . does no t con t r ib ute to un wa nt ed b i te dee pen ing) . In h igh ang le

Class II cases upper mo lar e x t rus ion shou ld be a void ed. In such

cases sho rt Class I I elast ics can be con side red .

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THE FOUR-STAGE TREATMENT PLANNING

PROCESS FOR CLASS III CASES

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The t re a tme n t p l a nn ing s e que nc e i s s imi l a r t o ihe C la s s I I

method, and the reader may wish to review pages 166 and

167 . Th e four s tages in p lann ing are described be low :

Stage 1 - s e t t in g a PIP fo r th e up pe r

inc isors

This invo lve s de c id ing wha t wou ld be the ide a l pos i t ion fo r

the upper inc isors . Is th is achievable? If not , can orthodont ic

too th move me n t s be us e d to re a c h a pos i t ion wh ic h i s l e s s

than idea l , but acceptable? Or wil l maxi l la ry surgery be

needed to reach an acceptable upper inc isor pos i t ion? In th is

way, a PIP (plan ned inc isor pos i t io n) for th e up per inc isors

can be es tabl ished (Fig . 8 .13) .

F i g .

  8 .13 The f i rs t s tage in C lass I II t re a tm en t p la nn ing

concerns upper inc isor pos i t io n . I t is necessary to de ter mi ne an

idea l pos i t ion and then dec ide whether i t can be ach ieved. I f

no t , a mod i f i ed p os i t i on m ay be app rop r ia te , w h ic h i s less than

i dea l ,  bu t a cceptab le . In th is way a 'p lann ed inc isor pos i t ion ' , o r

PIP,

  i s de te rm ined .

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Stage 2 - th e low er inc isors

Is i t poss ible to pos i t ion the lower inc isors in good

re la t ionship to the PIP for the upper inc isors? Can we achieve

the re qu i re d lowe r inc i s o r pos i t ion by o r thodon t i c s a lone ? In

Class III cases wi th mandibular excess , th is is f requent ly the

key ques t ion, espec ia l ly in growing individuals (Fig . 8 .14) .

Of te n the a ns we r w i l l be ' p roba b ly , p rov ide d g rowth w i l l no t

be unfavorable ' . Al te rna t ive ly , the answer may be 'poss ibly ,

but the re is conc ern ab ou t fu ture grow th, and i t i s preferable

to wai t for th is to express i t se l f (p . 234) .

F i g .

  8 .14 T he second stage o f t rea tm en t p lann in g invo lves

pos i t ion ing o f th e low er inc isors . Th is is f req uen t ly a key

conc ern i n Class III cases w it h m an dib ula r excess.

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Stage 3 - th e rem aining up per te eth

In the discussion on Class II treatment planning (p. 167),

stage 3 of the process concerned (he remaining lower teeth,

followed by stage 4  - th e rem ainin g up per tee th. In Class 111

treatment p lann ing the opposite app lies. It is beneficial to

evaluate (he remaining

  upper

  teeth  at  stage 3. If upper

premolar ex tractions are necessary (usually second premo lars)

then  it is normally logical to extract lower first premolar, in a

Class III case. However, if (he upper arch can be lrea(ed

without extractions, then  a  range of lower arch options needs

to be considered.

The third stage therefore involves deciding how to po sition

the rest of the upper teeth to fit the PIP for the upper incisors.

It normally assists Class III treatment mechanics if upper arch

extractions can be avoided. The dental VTO will confirm the

required movement of molars and canines (Fig. 8.15).

F i g .  8 .15 The th i rd s tage in C lass MM  t r e a t m e n t p l a n n i n g

inv o l v es dec id ing on t r ea tm en t m ec han ic s t o pos i t i on t he res t

of th e up per te et h cor rec t ly to f i t th e PIP for th e up per inc isors .

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Stage 4 - th e rema ining low er te eth

How can the rest of the lower teeth be positioned to fit the

planned lower incisor position (Pig. 8.16)? Does the case

require lower extractions to deal with lower arch crowding, or

to allow sufficient retraction of the lower incisors? Lower

premolar extractions assist in the retraction of lower incisors,

and are helpful to Class 111  treatment mechanics in many

cases.

  The denial VTO

6

  can be used to reach a correct

decision. In some Class III marginal extractions cases, second

molars may be considered (Case KB, p. 24 2).

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F i g .  8 .16 The f ina l s tage of C lass I II t re at me nt p lan nin g. I t is

necessary to assess low er arch c ro wd ing or spac ing, an d dec ide

how to pos i t i on t he res t o f t he l ow er t ee th t o f i t t he p lanned

lower inc isor pos i t ion.

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PIP COMPONENTS IN CLASS III

TREATMENT

For each Class III case, it is necessary to set a PIP as a

t rea tment goal which wil l resul t in the upper inc isors having

correc t antero-pos ter ior and vert ica l pos i t ioning, wi th

a ppro pr i a t e to rq ue (F ig . 8 .17 ) . I t i s be y ond the s c ope o f th i s

text to d iscuss and define prec ise goals . However , each

or thodon t i s t w i l l ha ve a v i e w a bou t whe re the uppe r inc i s o r

s hou ld be p l a c e d , a nd the re s hou ld be b roa d c ons e ns us in

most cases. As with Class II cases, before reaching a decision

about a suitable goal, i t is first necessary to analyze the

exis t ing pos i t ion of the inc isors , us ing e i ther convent ional

c e pha lom e t ry o r the Arne tt a na lys i s . The c o mp on e n t s a re a s

de s c r ibe d fo r C la s s II c a s e s (p . 168) . Th e s a me a p proa c h a nd

va lue s s hou ld be us e d whe n a na lyz ing the p re - t re a tme n t

upper incisor position for Class III cases.

F i g .  8 .1 7

  For each Class

  III

  case , a t t he s ta r t o f t r ea tm e n t

p la nn ing i t is necessary to es tabl ish a PIP wh ich w i l l resul t in

upper inc isors hav ing cor rec t A /P and ver t ica l pos i t ion ing, w i th

a p p r o p r i a t e t o r q u e .

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UPPER INCISOR MOVEMENT IN CLASS

TREATMENT

I laving se t a PIP for a case , control led up per inc isor

m ove me nt wi l l be needed to reach the goal . It is he lpful to

p la n the uppe r inc i s o r too th move me n t s in i s o l a t ion , a nd

the n c ons ide r the lowe r too th m ove m e n t s . Th e lowe r a rc h

may be dis regarded a t th is s tage , except as a poss ible source of

anchorage when us ing Class III e las t ics . In the fol lowing

pa ge s , r e c omme nde d M B T™ me c ha n ic s w i l l be de s c r ibe d fo r

uppe r inc i s o r too th move me n t s in C la s s I I I t r e a tme n t

s i tua t ions .

In mild Class III cases , wi th a no rm al maxi l la but

ma nd ibu la r e xc e s s , t he p re - t re a tme n t uppe r inc i s o r pos i t ion

may be c lose to the PIP. In th is s i tua t ion, the case may require

re la t ive ly l i t t le movement of the upper inc isors . However , in

many Class III cases , there wil l be a requirement to move the

upper inc isors mes ia l ly . In some maxi l la ry defic iency Class III

cases , i t can be a cha l lenge to achieve the required mes ia l

movement wi thout excess ive proc l ina t ion. I f a Class III case

requir es mes ia l mov em en t of up pe r inc isors , i t can be

achieved in two ways :

1.

  B y p roc l ina t ion a nd m e s ial mo ve m e n t o f up pe r inc i so rs

within the ava i lable bone (Fig . 8 .18) . Many Class III cases

re qu i re me s ia l move me n t o f uppe r inc i s o rs , l o ke e p pa c e

wi th the g rowing ma nd ib le . W he n uppe r inc i s o rs a re

proc l ined forwards , each 2 .5° of proc l ina t ion crea tes

a ppro x ima te ly 1 m m of s pa c e pe r s ide , o r 2 m m in to t a l .

Fo r th i s r e a s on uppe r p re mola r e x t ra c t ions a re no t

advisable in many (Mass III cases . I f upper premolars a re

extrac ted i t can be diff icul t or imposs ible to proc l ine upper

inc isors .

2 .

  By mes ia l m ov em en t of the maxi l la ry b on e (Fig . 8 .19) as a

re s u l t o f no rma l g rowth o r o r thodon t i c p roc e dure s .

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F i g .

  8 .1 8

  Mes ia l mo vem ent o f upper inc isor c rowns by

p roc l ina t ion .

F i g .

  8 . 1 9

  Mes ia l mo vem ent o f upper inc isor c rowns by mes ia l

mo vem ent o f the m ax i l la ry bone, as a resu l t o f g r ow th or

o r thodon t i c p rocedu res .

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Mesial movement of upper incisors

wi th in the bone

During (ooth leveling with the opening wires, there is a

tendency for upper incisors to move mesially due to bracket

tip, as previously discussed. In Class III cases, this is normally

beneficial, and moves the upper incisors towards PIP.

Likewise, at the rec tangular HANT and the rectan gular steel

wire stages, the A/P expansion and torque effects tend to

produce beneficial changes for most Class III cases. This can

be further augmented by the use of Class III elasiics. Because

of these spontaneous tooth movements during loolh leveling

and aligning, the early management of the upper arch in mild

Class III cases is norma lly straightforward.

Limits to mes ia l movement of upper

incisors

There are clear clinical limits which have to be observed when

moving upper incisors mesially. Problems can develop in

seemingly easy treatments, and the risks lie in two areas:

F i g .

  8 .20 Excess ive pro c l in a t io n o f uppe r inc isors bey ond 120°

to the m ax i l la ry p lane shou ld be avo ided as a gen era l ru le ,

a l tho ugh the re is i nd iv idua l va r ia t ion .

Excessive proclination. It is necessaiy to avoid excessive

proclination of (he upper incisors, otherwise un esthetic

appearance and inadequate function will result. As a

general rule, proclination of the upper incisors beyond

120° to the maxillary plane should be avoided, although

there is individual variation (Fig. 8.20). In some cases, less

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proclination than 120" may be appropriate. Gingival

recession and long clinical crowns can result from excessive

proclination.

Failure to fully achieve a positive overjet. This can be due

to the forward position of the lower incisors, or other

reasons, and the resulting bite can be difficult to manage

(Fig. 8.21). If this is allowed (o persist, then there is a risk

of enamel damage and/or root resorption. Accordingly, it

is unwise to attempt to correct a Class

 111

  incisor

relationship by orthodontic procedures alone, unless it is

clear from the outset that full correction can be achieved,

and a near normal overjet obtained.

F i g .

  8.21 It is unw ise to att em pt to co rrect a Class III incisor

re la t ion sh ip by or th odo nt ic s a lone , un less i t is c lear tha t a

nor ma l over je t can be ach ieved . A pers is ten t edg e- to- edg e b i te

can be assoc ia ted w i th roo t resorp t ion and/or enamel damage.

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Mesia l movement of max i l lary bone due

t o g r o w t h

Maxillary growth cannot be relied on as a useful factor in

correction of Class III maiocclusions. Generally in this type of

case, maxillary growth will not be favorable or helpful in

reaching the PIP for the upper incisor.

Mesia l movement of max i l lary bone due

to or thodont ic t rea tment

In growing individuals who have maxillary deficiency,

consideraiion can be given to treatment procedures which will

encourage orthopedic change within the maxil lary bo ne

(Fig. 8.22). These can include rapid maxillary expansion, and

the use of reverse headgear, but there is much controversy and

uncertainty surrounding the effect and stability of this type of

treatment. However, there is som e evidence in the literature

7

that favorable mesial change in the maxilla can be produced,

thereby assisting in mesial movement of the upper incisors

toward PIP.

F i g .  8 .22 I f f av o ra b le o r thop ed ic c hang e can be ac h iev ed in

th e max i l la , th is assists in mes ia l mov em en t of u ppe r inc isors

towards PIP.

'  :. .

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LOWER INCISOR MOVEMENT IN CLASS III

CASES

Dis ta l movement of the lower inc isors can be achieved by

d is ta l move m e n t o f the t ee th w i th in the ma nd ib u la r bon e , o r

by d i st a l move m e n t o f the ma n d ib le   itself,  when there is a

d i s p la c e me n t . Unfa vora b le me s ia l move me n t o f the lowe r

inc isors can occur because of mandibular growth. Each of

these poss ibi l i t ies wi l l be reviewed in turn and recommended

MBT™ mechanics wi l l be described for lower inc isor tooth

move me n t s in C la s s I II t r e a tme n t s i lua l ion s .

Dista l movement and ret rac t ion of the

lower inc isors wi th in the mandibular

bone

In most non-surgical Class III treatments, i t is helpful to

re t rac t and re t roc l ine the lower inc isors (Fig . 8 .23) . This can

c ompe ns a te fo r mi ld ma nd ibu la r p rogna lh i s m o r mi ld

ma x i l l a ry re t rogna lh i s m, a nd he nc e ma s k the unde r ly ing

s kele ta l d i s c repa nc y . Th e a na tom y o f the ma n d ib u la r b on e in

the lower inc isor region places l imits on what should be

a t tempted. Retrac t ion and re t roc l ina t ion beyond a f igure of

a pprox ima te ly 80° t o the ma nd ibu l a r p l a ne (F ig . 8 .24 ) i s

undes irable , because of the r isk of dehiscence and lack of

bone support for the over-re t rac ted inc isors . Also, denta l

esthetics and function will be adversely affected. The figure

o f 80° c ompa re s w i th the M ic h iga n no rma l

1

  of a pp rox ima le ly

9 5 " .  Al though 80" i s a good ru le o f thumb , in s ome c a s e s a

l imit of 85° may be appropria te , and a case-by-case

a s s e s s m e n t i s r e c o m m e n d e d .

The requ ired re t rac t ion an d re t roc l in a t ion of the lower

inc isors is normal ly achieved with the ass is tance of Class III

e las t ics , and t rea tment mechanics a re eas ier in cases where

lowe r t e e th ha ve be e n e x t ra c t e d . Lowe r f i r s t p re mola r

extrac t ions a re mos t favorable in ass is t ing lower inc isor d is ta l

mo ve m e n t , bu t l o s s o f lowe r s e c ond mo la r s c an a l s o be

con s idere d (Case KB, p . 242 ) .

If the lower a rch is managed on a non-extrac t ion bas is ,

Class III mechanics can be used to produce some re t rac t ion

an d re t ro c l ina t i on of the lower inc isors . This can pro du ce

d i s t a l l i pp ing o f the lowe r p re mola r s a nd mola r s , wh ic h in

turn reduces the ava i lable space for the lower th i rd molars

(Case MS, p . 241) . Early removal of lower th i rd molars can be

c ons ide re d in s ome c a s e s .

A non-e x t ra c t ion a pp roa c h to C la s s II I t r e a tme n t m a y no t

achieve suff ic ient lower inc isor movement for the needs of the

case.

  C or re c t ion o f the ma loc c lus ion ma y be pos s ib l e , bu t no t

over-co rrec t ion. Thus , there is no pr ovis io n in the result for

any la te growth changes , which occur re la t ive ly frequent ly in

Class III cases , espec ia l ly among male pa t ients .

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F i g .

  8 .23  Ret rac t ion and ret r oc l i na t ion of lowe r inc isors is

helpfu l in mos t non-surg ica l C lass I I I ! t reatments .

F i g .  8 .24 As a gene ra l r u le , r e t r ac t i o n and re t r oc l i na t i on o f

l ow er i nc i s o r s bey ond 80° t o t he m and ibu la r p lane i s

undes i r ab le .

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Dista l movement of mandibular bone -

d is ta l repos i t ioning

In many Class III cases, there is a mesial displacement of the

man dible at the start of treatment. As treatmen t progresses,

the  mandible repositions distally, to a position with the

condyles centered in the fossae. This favorable change can be

predicted at the treatment planning stage, and is a useful

adjunct to distal movement of the lower incisors within the

facial complex.

Dista l movement of mandibular bone -

res t r ic t ion of growth?

In the past, much attention was given to the use of orthopedic

devices, such as chin caps (Fig. 8.26), to restrict mandibular

growth in Class III cases with m andib ular progn athism.

8

is lam.net 

F i g .

  8 .25 In many C lass I II t rea tme nts , a mes ia l ma ndib ular

d i s p lac em ent is ev iden t a t t he s ta r t o f t r ea t m e n t . As t he

m and ib le r epos i t i ons d i s ta l l y du r i ng t r ea tm en t , and c ondy les

beco me cen tered in the fossae, lower inc isors mov e d is ta l ly in

the f ac ia l c om p lex .

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Clinical experience and research evidence   combine to suggest

that there is little advantage in using orthopedic measures to

attempt to restrict the final length of the mandible.

Accordingly, (he authors have ab ando ned the use of chin caps

and similar devices.

F ig .  8 .26 C l in icians have achieved l i t t le success w i th ch in caps an d

in Class I II cases . The au thor s ha ve ab an do ned th em .

o the r o r tho ped ic dev ic es , i n ten ded to r es tr i c t m a nd ib u la r g ro w t h

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CASE MS

A male patient, aged 13.11 years, with a slight Class III

skeletal pattern (ANB -1°) and MM average (2!>°). Lower

incisors were ret rocl ined at 84° to the mandihular plane.

There was a mild Class III facial profile.

O

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3

Molar relation ship was slightly C lass III bilaterally, and there

was a Class III incisor relationship, with lower incisors

crowded and retroclined. There was mild uppe r anterior

crowding with (he left first premolar in crossbite. Good-sized

third molars were developing in satisfactory positions. Second

molar extraction was considered and discussed, but after

discussion with the family, treatment proceeded on a non-

extraction basis.

www.al l islam.net  

Problem

F i g .  8 .27

F i g .  8 .30

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Standard metal brackets were used for optimal control. The

upper arch was fully set up with a .016 HANTwire. Bracketing

of lower incisors was delayed to allow separation and enamel

reduction. In this way, proclination of lower incisors during

alignment could be restricted. Sectional .015 multistrand

wires were used in the lower arch.

F i g .  8 .33

F i g .

  8 .36

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.

  ;

M.S.Beginning

1 3 . 1 1 y e a r s

6/7/96

F i g .

  8 .28

SNA

SN B

AN B

A-N FH

Po-N FH

W I TS

G o G n S N

F M

8 7 "

8 8 °

-1 °

1 m m

7 m m

-3 mm

' 2 4 °

19 °

M M / 2 5 °

1 to A-Po

1 to A-Po

t o Max P lane /

t o Mand P lane

3 m m

1 mm

1 1 2 °

8 4 °

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F i g .

  8 .34

F i g .

  8 .35

F i g .

  8 .37

F i g .

  8 .3 8

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Here , the case is seen af te r 10 months of t rea tment . Upper

and lower rec tangular

  I

  IANT wires a re in p lace , wi th a .036

' jockey ' wire (p . 82) to ass is t upper a rch expans ion. I t would

have been he lpful to have inverted low er can ine brack ets

when se t t ing up th is case , to ass is t torque control .

Lower second m olars had erup ted suff ic ient ly to pe rm it

band ing at th is s tage . Th e .01 9/ .0 25 lowe r HANT wire is

effec t ive in producing early correc t ion, and th is wire does not

pe rma ne n t ly d i s to r t due to ma s t i c a t ion , a s c a n ha p pe n wi th

steel wires in the lower second molar region.

After 13 m on ths of t rea tm ent , th e lower f irst mo lar ban ds an d

several brackets were repo s i t ione d, and rec tangu lar H ANT

wires were cont in ued in the upp er and lower a rch es .

F i g .  8 .42

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Normal uppe r and lower s tee l .01 9/ . 02 5 rec tang ular wires

we re us e d , w i th s ome uppe r a rc hwi re e xpa ns ion to ma in ta in a

correc t bucco-l ingual molar re la t ionship .

F ig .

  8.45

F i g .

  8 .48

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F i g .  8 .43 F i g .  8 .44

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F i g .

  8 .4 6

F i g .  8 .47

F i g .

  8 .49

F i g .

  8 .5 0

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73

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Frontal and buccal view after appliance removal. Active

treatment time was 26 months.

F i g .

  8 .51

A

  good dental result was obtained, but the panoral

radiograph shows impaction of lower third molars. The

patient was referred to a surgeon to discuss extraction of third

molars. With hindsight, the third molars could have been

extracted earlier in the treatment. This could have helped the

Class

 111

  treatment mechanics and avoided difficult

impaciions.

A  pleasing mild Class III profile. Little growth occurred during

treatment. There is som e risk of relapse from late ma ndibu lar

growth. Extraction of second molars could have produced a

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result where slight late growth could be more easily managed,

and where surgical extractions could have been avoided.

F i g .

  8 .57

Fig. 8.60

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P a l a t a l P l a n e &

P a l a t e C u r v a t u r e

M . S . B e g i n

M.S.Final

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Fig .

  8.55

S N A

S N B

8 6 °

8 8 °

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A N B ,

A N F H

Po-N FH

W I TS

G o G n S N

F M

M M

1 to A-Po

1 to A-Po

t o M a x P l a n e

/

t o M a n d P l a n e

■ 2 °

1 m m

7 m m

-4 mm

2 5 °

2 0 °

27

  °

5 mm

3 mm

1 1 5 °

8 9 °

Fig .  8.58

SN a t S

M.S.Begin

M.S.Final

Fig .  8.62

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M a n d .

  S y m p h a s i s

& M a n d . P l a n e

M.S.Begin

M.S.Final

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CASE KB

n

This fe ma le pa t i e n t wa s a ge d 13 .4 ye a rs a nd s h ow e d a

s l i g h t l y h i g h - a n g l e p a t t e r n ( M M 3 1 ° ) a n d m i l d C l a s s   III

d e n t a l b a s e s ( A N B 1 ° ) . T h e r e w a s p l e a s i n g b a l a n c e a n d

ha rmony to the fa c i a l p ro f i l e .

Molar re la t ionship was Class I , but there was a mild Class III

inc isor re la t ionship , wi th reduced overbi te . Lower inc isors

were crow ded and re l roc l ined, and there was s l ight upp er a rch

c rowding .

The fol lowing fea tures con tr ib ute d to the extrac t ion dec is io n

in this case:

• A goo d, or ma yb e s l ight ly flat p rofi le

• Sl ight ly high ang le pa t te rn

• An te r io r ope n b i t e t e nde n c y

• S l igh t t o mo de ra te a n te r io r c rowdin g .

Ther e was not suff ic ient c r ow din g to jus ti fy p rem ola r

e x t ra c tions w i th ou t r i s k ing unw a n te d p ro f i l e c ha nge . On the

o the r ha nd , non-e x t ra c t ion t r e a tme n t c ou ld l e a d to a n te r io r

b i t e -ope n ing .

The pan ora l radio grap h confi rm ed tha t a l l tee th were

de ve lop ing , i nc lud ing good-s i z e d th i rd mo la r s in good

dev elop me nta l p os i t io ns . I t was fe lt tha t the up pe r inc isors

Fig. 8 .63

Fig. 8.66

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shou ld be torq ued from 10 7° to a figure near to 115 °, but

tha t the vert ica l and A/P pos i t ions were sa t is fac tory . Thus , the

upp er and lower inc isor PIP could be c lose to the s ta r t ing

pos i t ion , bu t w i th s ome to r que c ha nge . A de c i s ion wa s m a d e

to re l ieve lower a rch crowding by extrac t ion of lower second

molars, and to use Class III elastics to align and retract the

lower f i rs t molars and premolars . Balancing extrac t ion of

uppe r s e c ond mola r s wa s p l a nne d ( i t wou ld ha ve be e n

diff icul t to man age th is Class III case if up per pre mo lars had

be e n e x t ra c t e d ) . The pa t i e n t a nd pa re n t s we re in fo rme d o f the

poss ible need to upright lower th i rd molars a f te r e rupt ion.

All tee th were banded or bracketed with s tandard meta l MB1""

brackets and .0 15 mu lt is t ran d wires were placed. Th e pa t ient

was referred for extrac t ion of a l l secon d pe rm an en t m ola rs .

Fig. 8 .69

F i g .

  8 .72

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K.B. Beginning

13.4 years

8/18/95

F i g .  8.64

S N A 7 7

S N B /  76

A N B

A N  FH

Po-N

  FH

W I T S

G o G n S N

F M

M M

1  to  A -Po

1

  to

  A -Po

1

  to Max

 P lane

t o Mand P lane /

1

- 5

-8

- 3

3 7

2 8

3 1

5

2

1 0 7

8 6

m m

m m

m m

0

'

"

m m

m m

F i g .  8.67

F i g .  8.68

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F i g .

  8.73

F i g .  8.74

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23

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1/1

1/1

23

m

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After

  1

 mon th, up per and lower .019/.025 HANT wires were

placed with Kobayashi ties on lower canines. The patient was

asked to wear full-time Class III elastics (75 gm).

After 4 months of treatment, a lower .016 HANT wire was

placed, and triangular elastics were used to close the anterior

open bite.

F i g .

  8 .78

After 7 months of treatment, a lower rectangular HANT wire

was resumed, and the patient was asked to wear a cross elastic

on the left side molars. Subsequently, upper and lower steel

rectangular wires were used to correct the anterior torque, and

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244

the incisor relationship was overcorrected. Normal settling

procedures (p. 294) were followed. An upper removable

acrylic wraparound retainer and a lower bonded retainer were

supplied.

F i g .

  8 .81

Active treatment time was 18 months. The case is seen here

after appliance removal.

F i g .

  8 .84

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F ig .

  8.76 F i g .

  8 .77

^

F i g .  8 .7 9 F i g .  8 .8 0

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F i g .  8 .82 F i g .  8 .83

F i g .  8 .85

F i g .

  8 .86

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At the end of treatment, there was good facial balance. The

A/I' position of incisors was unchanged relative to APo, and

torque measurements were close to normal.

Fig.

  8.87

Superimpositions suggest that some distal movement of

molars occurred, and that there was typical counter-clockwise

rotation of the occlusal plane in response to the Class III

elastics.

SN a t S

K . B . B e g i n

K . B . F i n a i

Occlusal photographs and panoral radiograph taken at the

end of treatment.

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Occlusal ph otograp hs taken 1 year after treatme nt a nd

panoral radiographs taken 7 months after treatment.

Subsequently all third molars erupted into good position.

This does not always happen, and third molar uprighting is

needed in some cases. (Case DO, p. 215)

246

Fig.  8.96

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. <'

K.B. Final

1S.4 years

9/9/97

Fig .  8.88

S N A

7 7

SN B 76

A N B 1

v  A-N FH

\  Po-N FH

)  W I T S

^  G o G n S N

F M

M M

1   t o A -Po

1 to A-Po

1 t o   Max P lane

t o M a n d P l a n e /

-5

-11

- 2

3 8

2 9

' 3 1

5

2

1 1 3

9 1

m m

m m

m m

m m

m m

Fig .  8.89

P a l a t a l P l a n e &

P a l a t e C u r v a t u r e

K.B.Begin

K.B.Final

M a n d .

  S y m p h a s i s

& M a n d . P l a n e

K.B.Begin

K.B.Final

Fig. 8.91

Fig .

  8.92

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Fig. 8.97

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F i g .

  8 . 9 8

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CHAPTER 9

Space c losure and s l id ing mechanics

Introduction  -  the need for efficient space

closure 250

Methods  of  space closure  252

Closing loop archwires 252

Sliding mechanics with heavy (ex-edgewise)

forces 252

Elastic cha in 254

Sliding me cha nics with l ight forces 25 4

Alternative mechanics for spaces resistant to

closure 258

Ob stacles to space closure 259

Anchorage balance during s pace  closure  260

Reciprocal space closure 260

Space closure in maximum anchorage cases -

crowding 260

Space closure in maximum anchorage cases -

protrus ion 261

Space closure in minimum anchorage cases -

' burning anchorage ' 262

Cas e  NH An adult first prem olar extraction case,

with a mi ld Class III skeletal prob lem 26 4

Case MO'T A first prem olar extraction case

  272

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INTRODUCTION - THE NEED FOR

EFFICIENT SPACE CLOSURE

Although .space c losure is som et im es n eede d in n on-

extraction cases, the subject is gen erall y discu ssed relative to

prem olar extrac t ion cases . Space c losure is carr ied ou t in the

s a me ma nne r in bo th g roups , a nd a l though the s ub je c t o f

orthodont ic extrac t ions has been controvers ia l in the pas t , i t i s

now accepted tha t extrac t ion of four prem ola rs is benefic ia l in

som e cases. The 7 m m of space provi ded in each qu adr ant

may be used to benefi t the pa t ient in one or more of the

fol lowing ways :

• Rel ie f of c row ding, to achiev e s table a l ign m en t of the

dent i t ion

• Retract ion of up per anter ior tee th to correc t the overjet in

Class 11/1 cases

• Retraction of lowe r incis ors to assist cor rect ion of Class III

cases

• Retrac t ion of upp er and lower inc isors to impro ve fac ia l

profi le or occ lus ion in bimaxi l la ry proc l i i ia t ion cases

• Mes ia l mo vem ent of mo lars , increas in g space for th i rd

mola r e rup t ion .

In ma x imum a nc hora ge c a s e s , mos t o f t he s pa c e w i l l be

used to re l ieve crowding (Fig . 9 .1) or to re t rac t inc isors

(Fig. 9.2).

Howe ve r , i n min imum a nc hora ge c a s e s , whe re c rowding o r

p ro t rus io n i s min ima l , l e ss tha n 7 m m of s pa c e in e a c h

quadrant wi l l be needed for re l ie f of c rowding or inc isor

re t rac t ion. In these cases , there wil l be a need to c lose the

res idual spaces by mes ia l movement of f i rs t and second

mola rs , p rov id ing more s pa c e fo r e rup t ion o f th i rd mo la r s

(Fig. 9.3).

R e c ip roc a l s pa c e c los u re o f p re mo la r s pa c e (F ig . 9 .4 ) w i l l

be appropria te in many cases , espec ia l ly where res idual spaces

are small. But in other cases it is necessary to vary the

t re a tme n t me c ha n ic s a nd to c on t ro l t he a nc hora ge ba la nc e ,

e i ther to re t rac t inc isors (Fig . 9 .5) or to mes ia l ize molars

(Fig. 9.6).

Consequent ly , in an eff ic ient or thodont ic prac t ice , there is

a need for a re l iable method of space c losure , which wil l

a l low c on t ro l o f a nc h ora g e ba la nc e .

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l l

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  -  fit

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F ig .  9.4 Reciprocal space c losure.

F i g .  9 .5 Inc isor re t r ac t io n.

F i g .  9 .6 M es ia l m o la r m o v em ent .

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^ s a a n n M n i H i

APo APo

F ig .

  9 .1 Premoiar ex t rac t i on spaces may be used to re l ieve cro wd ing an d ach ieve s tab le a l ignm ent o f the den t i t ion .

APo APo

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F ig .  9 .2 Incisors and can ines may be re t rac ted in to prem oiar e x t rac t ion spaces, thereb y im pro v ing th e ba lance o f the fac ia l p ro f i le in

cases wi th excessive prot rus ion .

APo APo

F ig .  9 .3 Mes ia l mov em ent o f m olars may be needed to c lose res idua l space in min i mu m a ncho rage cases. Th is w i l l p rov ide more

space fo r e rup t ion o f th i rd molars .

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METHODS OF SPACE CLOSURE

• Clos ing loo p archw ires

• Sl id ing me chanic s wi th heavy forces

• Elastic chai n

• Sl id ing me chan ics wi th l ight co nt i nu ou s forces

( r e c o m m e n d e d ) .

Closing loop archwires

Edward Angle favored a non -extra c t ion app roa ch 10 a l l cases

and space c losure mechanics were not normal ly needed. Later ,

however , c los ing loop archwires became part of t radi t ional

edgewise mechanics , as described by Tweed.

1

  liach

rec tangular s tee l wire typica l ly had four loops - two omega

loops and two c los ing ( teardrop) loops - and had lo be

individual ly made for each pa t ient . There was a l imited range

of ac t ion before the om ega l oo p came in to contac t wi th the

mola r tube .

Clos ing loop archwires were f lexible , because of the loops ,

but appl ied a heavy space c losure force in the extrac t ion s i tes .

There was therefore a need for extra t ip , ro ta t ion control , and

to rque c on t ro l du r ing s pa c e c los u re w i th the s e me c ha n ic s ,

and th is was achieved by plac ing individual bends in the wire

for each tooth . These bend s cou ld be se lec t ive ly removed or

reduced la te r in the t rea tment .

The re we re d i s a dva n ta ge s to th i s me thod o f s pa c e c los u re .

A lot of wire bend ing t im e was needed , and the forces were

he avy ; s l id ing me c h a n ic s we re poor , a nd th e me c h a n i s m ha d

only a short rang e of ac t iva t ion. Clos in g loop archw ires

(Fig . 9 .7) are therefore no t reco m me nd ed for rou t ine spac e

Sl id ing mechanics wi th heavy

(ex-edgewise) forces

A wide ra nge o f t r e a tme n t me c ha n ic s wa s e va lua te d du r in g

the 19 70s , in the ear ly days with the preadjus ted bracket

s ys t e m. A t t e mpts we re ma de to a pp ly t r a d i t iona l e dge wis e

fo rc e l e ve l s (500-600 gm) to the ne w b ra c ke t s . I t wa s found

tha t heavy space c losure forces (for example us ing s tee l

Ple tcher springs on .018/ .025 s tee l wires ) caused unwanted

t ip,

  ro ta t ion , a nd to rque c ha nge s (F igs 9 .8 -9 .11 ) .

When these heavy forces were used for space c losure , there

was therefore a need for extra l ip , ro ta t ion control , and torque

c on t ro l . Th i s a dd i t io na l c o n t ro l c ou ld b e a c h ie ve d by

de s ign ing e x t ra t i p , ro t a t ion , a nd to rque in to the b ra c ke t s .

This was the back gro und lo the 'extrac t ion ser ies ' or

' t r a ns l a t ion s e r i e s ' b ra c ke t s de ve lope d by Andre ws .

2

  However,

such brackets re ta ined the extra fea tures through to the end of

t re a tme n t (un l ike s t a nda rd e dge wis e , wh e re a nc ho r be nds , for

example , could be adjus ted in the f ina l s tages) . Cases t rea ted

with extrac t ion ser ies bracke ts an d heavy forces therefore

p la c e d he a v ie r de ma nds on a nc hora ge e a r ly in the t r e a tme n t ,

an d often had over-correc ted too th pos i t ion s a t th e end of

t rea tment (Fig . 9 .12) .

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helpful in c los ing a smal l amount of res idual space , espec ia l ly

in adults .

~I Normal space closure

I Too rapid space closure

F i g .

  9 .7 C los ing loop archwires wer e par t o f t r ad i t ion a l

edgewise t re a tm ent mechan ics . They we re ind iv idua l ly m ade

for each pat ien t , and had a l imi ted range o f ac t ion before the

omega loop came in to con tac t w i th the mo la r tube .

F i g .

  9 .8 Too rap id inc isor re t rac t ion can leave the inc isors w i t h

inadequa te to rque .

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.-A

  ,

Normal space closure

Too rapid space closure

2   Too rapid space closure

F i g .  9 .9 Too rap id s pace c los u re a ls o a l l ow s un fav o rab le t o r qu e

e f fec t s on upp er and l ow er m o la r s . The m ov em en ts s ho w n a re

no t f av o rab le f o r p roper f unc t i ona l c hew ing m ov em ents , and

m o la r s i n t h i s pos i t i on r equ i r e add i t i ona l t o rque to r eac h i dea l

pos i t i on .

F i g .  9 .10 In response to to o rap id space c losure, the re is an

inc reas ed tendenc y fo r r o l l i ng i n o f t ee th ad jac en t t o ex t r ac t i on

sites.

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F i g .  9 .11 U n w a n ted e f f ec t s o f ov e r - r ap id s pac e c losu re i nc lude

low er m o la r t i pp ing , w i t h ex t r us ion o f t he d i s ta l c us ps ,

espec ia l ly in h igh -ang le cases . A lso, excess ive sof t t issue b ui ld -up

can occur , which somet imes prevents proper space c losure, or

causes re-opening of ex t rac t ion space.

F i g .  9 .12 Th is pa t i en t w as t r ea ted us ing upper c an ine b rac ke ts

w i t h  11 ° o f t ip , leav ing the upp er canine roots in c lose

prox im i t y t o t h e p rem o la r r oo t s .

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Elastic chain

Elastic chain is not recommended for closure of large spaces,

because of force level issues. For example, 'C-l' chains

stretched from first molar to first molar, initially generate

400 gm of force in the upper arch and 350 gm of force in the

lower arch. This places them in the force range just below

closing loops and steel Pletcher coil springs. In a first

premolar extraction case, for example, over-stretched chain

links in the extraction sites (Fig. 9.13) will cause rotation of

adjacent teeth. Under-stretched chain links in the extraction

sites (Fig. 9.14) will not produce any space closure.

Flastic chain is useful for dealing with one or two minor

spaces towards the end of treatment (p. 295) and light chain

can be helpful in preventing spaces from opening late in the

treatment, when finishing .014 wires are in place.

Sl id ing mechanics wi th l ight forces

In 1990 , a  m e t h o d  of c on t ro l l e d s pa c e c los u re  was  d e s c r i b e d '

u s ing s l id ing me c ha n ic s . Th i s

  has

  proved effec t ive

  and

  re l iable

for many years , and has s e e n w ide s p re a d a c c e p ta nc e by

c l in i c i a ns . The a u t h o r s r e c o m m e n d  the  fo l lowing t e c hn iq ue :

•  A r c hw ir e s .  R e c ta ngu la r 019 / .02 5 s t ee l w i re s ( 'wo rk ing

wires ' ) (Fig .

 9.1 5) are

 r e c o m m e n d e d w i t h

 the .022

 s lot ,

because th is s ize

 o f

  wire g ive s good ove rb i t e c on t ro l wh i l e

a l lowing f re e s l id ing th rough

  the

 buc c a l s e gme n t s . T h inn e r

wires tend  to  give less overbi te  and  to rque c on t ro l . Th ic ke r

wires somet imes res t r ic t f ree s l id ing of  m o l a r s and

p r e m o l a r s .

•  S o l d e r e d h o o k s .  The a u t h o r s c o n t i n u e  to  prefer  0.7

soldered brass hooks . Soft s ta in less s tee l  0.6  s o lde re d

h o o k s  can be a  useful a l te rna t ive ,  and s o m e a du l t pa t i e n t s

prefer

  the

 a p p e a r a n c e

  of

 the s e .

 The

 m o s t c o m m o n h o o k

p o s i t i o n s  are 36 mm or 38 mm  ( u p p e r )  an d 26 mm

( lowe r ) , me a s u re d a long  the l ine of the arch (Fig . 9 .16) .

Th e a u th o rs f ind tha t  the 26 mm  lowe r hook pos i t ion f i t s  a

h igh pe rc e n ta ge of cases, but  the re  is grea ter variabi l i ty  in

h o o k p o s i t i o n s  in the upp e r a rc h , due to too th s i z e

va r i a t ion a m on g upp e r l a t e ra l i nc i s o rs . The re fo re ,  a  wide r

ra nge  of  upp e r hoo k s i z es ne e ds  to be s toc ke d .

F i g .

 9.13

  Over-s t re tched e las t ic cha ins can cause unwanted

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ro ta t ions .

F i g .

 9.14

  Under-s t re tched e las t ic cha ins w i l l  not  achieve space

closure.

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Passive tieba cks. Before starting space closure, it is

recommended that the rectangular steel .019/.025 wires be

left in place for at least 1 month with passive tiebacks

(Fig. 9.17). This allows time for torque changes to occu r o n

individual teeth and for final leveling of the arches, so that

sliding mechanics can proceed smoothly when active

tiebacks are placed.

Active tiebacks using elastom eric m odu les. In daily

clinical practice, these are simple, economical, and reliable.

Placement is not difficult and can be delegated routinely,

with few complications. Active tiebacks using elastomeric

mo dule s are preferred for space closure in mo st cases, even

though nickel-titanium springs have been shown to be

more reliable and effective,

1

  as discussed below.

Force levels. Elastic tiebacks were originally described

1

using an elastomeric module, of the type used to hold

archwires on to brackets, stretched to twice its normal size.

This was found to give a force of 5 0- 10 0 gm, if the mo dule

was pre-stretched or 'worked' before use. If used direct

from the manufacturer, without  pre-stretching, the force

may be 2 00- 30 0 gm greater.'

5

 The force delivered by the

elastic module varies with the type of module used, pre-

stretching before use, and the amount of stretching when

placed. It has been reported that different clinicians have

successfully used different types of module, with different

pre-streiching and different amounts of stretching when

placed in the mouth.

6

  Despite these variations in technique

and force levels, there is widespread acceptance that elastic

tiebacks achieve good space closure. It therefore seems that

3 6 - 3 8 m m

.019/.025

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F i g .

  9 .15

  Rec tangular .019/ .025 s tee l 'w or k in g ' w i res are

r e c o m m e n d e d .

F i g .  9 .16  The mos t com mo nly used hoo k pos i t ions .

F i g .  9 .17  Passive t iebacks are recomm ende d at the t i me of p lace men t of re c tangu lar .019/ .025 stee l w i res . These are used for a t leas t

1 month to a l low torque changes to occur on ind iv idual teeth. Later , ac t ive t iebacks are used for space c losure.

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precise force levels are not essential for clay-to-clay success,

and tha i adequate space c losure occurs in mos t cases ,

provided the genera l concep t is fo l low ed.

Tr a m po l in e e f fe c t. C l in ic a l e xpe r i e nc e ha s s how n tha t

space c losure can cont inue for severa l months in pa t ients

who have fa i led to present for normal adjus tments , even

whe n the e l a s tome r ic modu le i s i n poor c ond i t ion a nd

apparent ly de l ivering very l i t t le force .

  I

  low can th is

cons is tent c l in ica l experience be expla ined? One can

specula te tha t there may be a ' t rampol ine effec t ' which

occurs during mas t ica t ion, and which can resul t in an

in te rmi t t e n t pumping a c t iva t ion .

T y p e o n e a c t i v e t i e b a c k ( d i s ta l m o d u l e ) . T h e . 0 1 9 / . 0 2 5

rec tan gular s tee l a rchw ire is p laced , wi th m od ul es or wire

l iga tures on a l l brackets (Fig . 9 .18) . The e las tomeric

m od u le i s a t t a c he d to the f ir st o r s e c ond mo la r hoo k . A

.010 l iga tu re is u s e d , w i th one a rm be ne a th the a rc hw i re

(F ig . 9 .19 ) . Th i s ma k e s the a c t ive t i e ba c k mo re s t a b le , a nd

helps to keep the l iga ture wire away from the gingiva l

tissues.

Typ e two a c t ive t i e ba c k (m e s ia l m od u le ) . Th i s fo l lows the

s a me p r inc ip le a s the type one , bu t t he e l a s tome r ic modu le

i s a t t a c he d to the s o lde re d h oo k on the a rc hw i re . The

.01 9/ .0 25 rec tan gular stee l a rchw ire is p laced w ith

e las tomeric modules or wire l iga tures on a l l brackets ,

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F i g .

  9 .1 8

  Before p lac ing the type one ac t ive t ieback , th e .019 / .025 rec tan gu lar s tee l a rch w ire is p laced , w i t h e las tome r ic mod u les o r

w ire l iga tures on a l l b rackets .

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F ig .

  9.19

  The com ple te d type one ac t ive t ieback . It is he lp fu l to carry one arm o f the l ig a tur e w i re ( i) under the arc hw ire . An

e las tomer ic modu le is s t re tched to tw ice i ts unstre tched s ize ( i i ) .

256

F i g .

  9 .2 0

  A typ e one ac tive t ieback jus t be fo re p lac eme nt .

F i g .

  9 . 2 1

  A lowe r type one ac t ive t ieba ck. Th is shows m in im al

ac t iva t ion o f the e las tomer ic , and s l igh t ly more s t re tch ing cou ld

be used.

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except the premolar brackets (Fig. 9.22). A .010 wire

ligature is attached to the first or second molar hook, with

several twists in the wire, and then attached to

 an

elastomeric module on the archwire hook. Finally, a

normal module is placed on the premolar brackets to cover

the tieback wire and the archwire (i

;

igs 9.23 & 9.24). With

the type one and type two tiebacks, the elastomeric

modules are normally stretched to twice their resting size

for activation. If oral hygiene is good, adjustment visits

may be less frequent; they may be re-activated after 4 to 6

weeks, and remain in place for two visits. If oral hygiene is

poor, the elastomeric modules may deteriorate and require

replacement at eveiy visit. In some cases, in the final stages

of space closure, it may be helpful to use two modules, or

to augment the tieback with a 10- or 12-link elastomeric

chain from molar to molar.

Active tiebacks using a

  nickel-titanium coil spring.

Nickel-titanium springs can be used, instead of elastomeric

modules, if large spaces need to be closed, or if there are

infrequent adjustment opportunities (Fig. 9.25). Recent

work by Samuels et al

7

  has recomme nded that the opt imal

F i g .  9 .2 2

  Be fo re p lac ing t he t y pe tw o ac t i v e t i ebac k , t he . 019 /.025 rec tangu la r s tee l a r c hw i re is p lac ed , w i t h e las tom er i c m odu les o r

w i re l igatures on a l l brackets , except the premolar brackets .

F i g .

  9 .2 3  The c om p le ted t y pe tw o ac t i v e t i ebac k . Th is f o l l o w s the s am e p r inc ip le as t he t y p e one ac t i v e t i ebac k , bu t t he m odu le is

a t t ac hed an te r i o r l y . The f i na l e las tom er ic m odu le ( e) is p lac ed a f t e r t he a r c hw i re and the t i eba c k . I t s t ab il i zes t he t i ebac k w i re and

helps to d i rec t i t away f rom the sof t t issues .

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F i g .

  9 . 2 4  Type tw o ac t ive t iebacks (mes ia l mod ules ) in uppe r

and low er arches . The e las tomer ics are s t re tched max imal ly in

th is ph ot og rap h - ideal ly , in mos t t rea tme nts , s l ight ly less

s t retch ing is ap pro pr ia te. For f ina l space c losure, i t is somet imes

he lpfu l to p lace tw o e las to mer ic mo dules . See a lso F igure 9.98,

p. 275.

F i g .  9 . 2 5

  A l t h o u g h n i c k e l - t i t a n i u m s p ri n gs p r o d u c e m o r e

cons is tent space c losure th an e las tom er ic mod ules , the a utho rs

cons ider the ease and s impl ic i ty o f the modules make these

pre fe rab le i n m os t t r ea tm en ts . N i c k e l - t i t an ium s p r ings m ay be

usefu l in cases wh ere a large a mo un t of space c losure is

requ i r ed , o r w here t he re a re i n f r equen t ad jus tm en t

o p p o r t u n i t i e s .

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force for space closure is 150 gm w hen using nickel-

titanium coil springs as the force for space closure. The

150gm springs were found to be more effective than

lOOgm springs, but no more effective than 200gm springs.

This work confirmed their earlier findings" that nickel-

titanium springs produce more consistent space closure

than elastomeric modules. It suggests the use of light

closed coil nickel-titanium springs (344-150 and 346-150

3M llnitek) to give a force of 150 gm. Springs should not

be expanded beyond the manufacturers recommendations

(22 mm for the 9 mm springs, and 3 6 mm for the 12 mm

springs).

Nattrass et al

6

  confirmed that force decay with

elastomeric chains is rapid in the first 24 hours and is

affected by environm ent and tempe rature. Force decay did

not occur to the same extent with nickel-titanium springs.

Although the research evidence favors the use of nickel-

titanium coil springs for more rapid space closure, the

authors continue to use elastomeric modules for space

closure in most cases. If spaces are closed too rapidly,

incisor torque can be lost, and requires several months to

regain at the end of space closure. Elastomeric modules are

easy to use, economical, and work well in most clinical

situations. Although coil springs can close all the space

without requiring replacement at mon thly visits, this is

largely a theoretical advantage, because it is preferable to

lake out th e wires to check and sh orten them every 1 or 2

months during space closure.

Alternat ive mechanics for spaces resistant

to c losure

In a few cases, it may be found that spaces are slow or

difficult to close with the normal mechanics. If no obstacles

to space closure are evident (see below), alternative

mechanics may be considered. Tiebacks with two modules

may help, or a looped archwire can be made. A useful

alternative in difficult space-closure situations is the Hycon®

device from Edenta. This has been used successfully by one of

the authors for 4 years in selected cases.

The device consists of

 a

  centimeter segment of

 21

 x 2 5

rectangular wire, to which is soldered a 7 mm screw device.

The rectangular segment is placed in the do uble o r triple lube

on the molar, and bent over dislally. The screw is provided

with a large head, lo which a ligature wire can be loosely

connected . The ligature wire is then extend ed forwards and

tied to the archwire hoo k. The developer of the Hycon® device

was DrWinfried Schiitz, a German orthodontist, and he

suggests thai a small screwdriver be used twice per week to

turn the screw one full turn (1/8 mm) in a clockwise

direction. Thus, approximately

  1

  mm of space closure is

accomplished per month (Case NH, p. 268). This device

provides a veiy short-acting but strong force that essentially

overcomes any frictional concerns. If overdone, however, it

will lead to significant archwire deflection, which should be

avoided. The I lycon® device, like palatal expanders,

distraction osteogenesis screws, and so me mo lar distalizing

devices, requires diligent patient cooperation to ensure

success.

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Obstacles to space closure

In a lmos t a l l cases , space c losure is easy and proceeds

une ve n t fu l ly . On ly ra re ly a re p rob le ms e nc oun te re d . I f i t

app ears tha t space is not c los in g as i t sho uld (ab out 1 m m per

month typica l ly) , the spaces should be careful ly measured a t

successive visits . If they are n ot re duc ing , or if wir e is not

appearing gradual ly from the dis ta l of the molar tube , then

poss ible obs tac les should be eva lua ted before resort ing to

different mechanics :

• In a d e q ua te l e ve l ing . The work ing rec t a ngu la r w i re s ne e d

to be in place for at least 1 m o nt h wi th pass ive ties (p .

2 5 5 ) ,  to ensur e pro per leve l ing and freedom from pos t er io r

torque pressure . Also, i t i s important not to a t tempt

overbi te correc t ion us ing reverse curve in the lower

a rc hwi re a t t he s a me l ime a s a t t e mpt ing s pa c e c los u re .

Overbi te control should be achieved before space c losure .

• Da m ag ed bra cke ts . Lower f irst mo lar brackets can be

dam age d an d part ly c losed dow n by excessive bi t in g forces .

As a s ho r t - t e rm me a s u re , t he w i re ma y be th inn e d in tha t

area , but i t i s be t te r to replace the molar a t tachment . The

us e o f f i r s t mo la r non-c onve r t ib l e lube s i s r e c omme nde d ,

as these are not suscept ib le to damage in the same way as

f i r s t mo la r c onve r t ib l e tube s , a nd the y ha ve o the r

a dva n ta ge s (pp 53 & 54) .

• Inc o r re c t fo rc e l e ve l s . Fo rc es a bov e the re c o mm e nd e d

levels can cause l ipping and fr ic t ion, and thus prevent

s pa c e c los u re . Ina de qua te fo rc e ma y s ome t ime s be a c a us e

o f s low- o r non-s pa c e c los u re in a du l t t r e a tme n t . Fo rc e

levels need to be in ba lance with a rchwire s ize and

.019 x.025

.016 x.022

+47%

)

F i g .  9 . 2 6

  Force levels need to be in ba lan ce dur ing space

c losure and s l id ing mechanics . A .019/ .025 s tee l rec tangluar w i re

is r ec om m en ded in t he . 022 s lo t .

3 i

F i g .  9 .2 7

  Space c losure can be pre ven ted by in ter feren ce f rom

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s t i f fness . I f they are not in ba lance , a rchwire deflec t ion and

un wa nte d fr ic t ion can occur . I t has been show n tha t

archwire deflec t ion causes fr ic t ion

8, 9

. Also, recent research

in Japan

1 0

  ha s me a s u re d th e a m ou n t o f de f l e c tion o f

rec tangula r a rchw ires in response lo typica l space c losure

force . I t has been shown tha t on average 47% more

de f l e c t ion oc c u rs w i th a .016 / .022 wi re c ompa re d w i th a

.019 / .025 wi re (F ig . 9 .26 ) .

• In t e r fe re nc e f rom o pp os in g t e e th (F ig . 9 .27 ) . Th i s c a n

prevent lower space closure, and it is necessary to carefully

check th e occ lu s ion. In the pas t th is was of ten re la ted to

vert ica l bracket-pos i t ioning errors in the upper a rch. The

use of gauges has reduced these errors , and in terference is

s e ldom a n obs ta c l e now.

opp os ing tee th . I n t h i s i l l us t r a t i on , t he b rac k e t on t he upper

prem olar is p laced too far g ing iva l ly , an d the pr em olar c row n is

prevent ing fu l l c losure of lower space.

Sof t t i s s ue re s i s t a nc e . G ing iva l ove rg rowth in the

extrac t ion s i tes can prevent space c losure , and can cause

space to re -op en af ter appl ia nce rem oval (Fig . 9 .1 1,

p .

  25 3) . I t c a n a l s o be a p rob le m wh e n c los ing a n uppe r

mid l ine d i a s t e ma . C a re i s ne e de d to ma in ta in good o ra l

hygiene and avoid loo rapid space c losure , as these can

contr ibute to loca l g ingiva l overgrowth. In a few cases ,

local surgery to sofl t issue may be indicated.

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ANCHORAGE BALANCE DURING SPACE

CLOSURE

Reciprocal space closure

If anchorage has been properly plan ned and controlled during

earlier stages of treatment, reciprocal space closure can be the

method of choice in many cases. Theoretically, this leads to a

50:50 movement of incisors and molars (Fig. 9.28), which is

clinically acceptable in many cases, especially if (he spaces are

small.

Space c losure in m ax im um anchorage

cases - cro w di ng

Most of the premolar extraction space is used to relieve

crow ding in these cases. This require s careful anc hora ge

control early in treatment (Case NI I, p. 266), but then the

space closure stage is normally minimal, because the available

space has mainly been used to relieve crowding.

F i g .  9 .2 8 Rec iprocal space c losure. This is the me th od o f choice in man y cases.

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260

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..  -f

Space c losure in maximum anchorage

cases - pr otr us ion

Space closure is important in these cases. Good anchorage

control is needed at the space closure stage in order to achieve

incisor retraction into th e available extraction sp ace. First

prefholars are normally chosen for extraction. Second molars

are included in the set-up if possible. In this way, six anterior

teeth are balanced against six larger posterior teeth, giving a

theoretical advantage in anchorage balance (Pig. 9.29). Palatal

bars and lingual arches may be used during the alignment

stage, to restrict mesial movement of molars, and the palatal

bar may be continued into the space closure stage. If patient

cooperation is available, a headgear may also be considered,

sometimes with Glass 111 elastics (Pig. 9.30).

uu uuu

F i g .

  9 .30 I n m ax im u m anc horage c as es , l ow er a r c h re t r a c t i on

may be sup po r ted by C lass I II e las t ics t o u pp er mola rs , w o rn

s im u l taneous l y w i t h a headgear .

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F i g .  9 .29 Spac e c losu re i n a m ax im u m anc ho rage c as e w i t h p ro t r u s ion .

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poss ibi l i ty of the a lveolar bone becoming narrow. Light Class

II e las t ics ( lOO gm ), worn jus t a t n ight , can sup po rt mes ia l

move me n t o f the lowe r mo la r s du r ing s l id ing me c ha n ic s . The

tor qu e of + 17° for up pe r centra l inc isors and +10 ° for upp er

la te ra l inc isors seems to be c l in ica l ly he lpful in mainta ining

the A/P pos i t ion of the upper labia l segment , aga ins t the 10-

to 1 2- ho ur Class II e las t ic force . Th e m olar s rece ive a 24-h our

mes ia l iz ing force , which is grea ter in the low er a rch, du e to

the light Class II elastics.

If careful t re a tm ent m ech anic s a re fol lowed af te r extrac t ion

of second premolars , i t i s poss ible to c lose space mainly by

mes ia l movement of f i rs t and second molars , increas ing

a va i l a b le s pa c e fo r th i rd mo la r s , a nd ma in ta in ing the pos i i ion

of the lower incisors in the facial profile.

F i g .

  9 .3 1  Spac e c los u re i n a m in im um a nc horage c ase - ' bu rn ing anc hora ge ' .

t o

o

m

Space c losure in minimum anchorage

cases - 'b ur nin g an cho rage '

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n The se are cases wh ere there is only mild crow ding or

m

pro t rus ion , bu t whe re e x t ra c tion o f p re mola r s i s ne e de d to

Q

  achieve pro per t rea tm ent goals . It i s necessary to c lose

£ re ma in ing s pa c e s ma in ly by me s ia l mo ve m e n t o f mo la r s ,

•*> ther eby incr easin g ava ilab le spac e for third mo lars an d

3>

  protec t ing facial profi le . Secon d prem olar s may be chos en for

S extrac t ion in th is type of case , and secon d mo lars a re

i /i nor ma l ly not ban de d or bracketed . The th in kin g beh ind th is

a ppro a c h i s ba s e d on the ma the ma t i c a l ba l a nc e o f two mo la r

tee th aga ins t e ight anter ior tee th during s l id ing mechanics .

log ic a l ly , ma in ly me s ia l mo la r move me n t c ou ld be e xpe c te d

(F igs 9 .31 & 9 . 32 ) .

2 In th is type of case , i t i s correc t to co m m en ce t rea t me nt

3>  soo n af te r extrac t ion of secon d prem olars , to avoid the

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F i g .

  9 .3 2  ' Be fo re ' and ' a f t e r ' r ad iog ra phs o f a s ec ond p rem o la r ex t r ac t i on c ase . M es ia l m ov em ent o f l o w e r f i r s t m o la r s has c rea ted

space for second and th i rd molars .

262

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w w w . a l l i s l am. ne t

REFERENCES

1 Tweed, C H 1966 C l in ica l or thodont ics . Mosby , St Louis

2 The ' A ' C ompany S t ra igh t -W i re App l i anc e . An e igh t pag e des c r i p t i v e

brochure. 'A ' Company , San D iego, CA, USA

3 Benn et t J C , Mc Lau ghl in R P 1990 Con t ro l l ed space c losure w i th a

p read jus t ed app l i anc e s y s t em. J ou rna l o f C l in i c a l O r t hodo n t i c s

24 : 251 -260

4  Samuels R H, Rudge

  S

  J , Mai r L H 1993 A com par iso n of t he ra t e o f

s pac e c los u re us ing a n i c k e l - t i t an ium s p r i ng and an e las t ic m odu le : a

c l i n ic a l s t udy . Amer i c a n J ou rna l o f O r t hod on t i c s and D en t o f ac ia l

Or t hoped i c s 103 : 464 -467

5 Nat t rass C, I re land A J, Sherr i f f M 1997 An in ves t igat ion in to t he

p lac emen t o f f o r c e de l i v e ry s y st ems and t h e i n i t i a l f o r c es app l i ed by

c l in ic ians dur ing space c losure. Br i t ish Journal o f Or thodont ics

24:127-131

6 N at t rass C, I re lan d A J , Sherr i f f M 1998 The ef fec t o f en v i ro nm en ta l

f ac t o rs on e las t omer i c c ha in and n i c k e l t i t an ium c o i l s p r i ngs .

Eu ropean J ou rna l o f O r t hod on t i c s 20 : 169 -176

7 Samuels R H, Rudge S J , Mai r L H 1998 A c l in ica l s tudy of space

c los u re w i t h n i c k e l - t i t an ium c los ed c o i l s p r i ngs and an e las t i c mod u le .

Ame r i c an J ou rna l o f O r t hodon t i c s and D en t o f ac ia l O r t ho ped i c s

114 : 73 -79

8 Pizzoni L, Ravn hol t G, Mels en B 1998 Fr ic t ion al forces re la t ed to se l f -

l i ga t i ng b rac k e t s . Eu ropean J ou rna l o f O r t hodon t i c s 20 : 283 -291

9 O'Rei l ly D , Dowl ing P A. Lage rs t rom L, Swar tz M L, 1999 An ex v iv o

I nv es t i ga t i on i n t o t he e f f ec t o f b rac k e t d i s p lac emen t on t h e

res is t anc e t o s l i d i ng . B r i t i s h J ou rna l o f O r t h odon t i c s 26 : 219 -227

10 O uchi K, Kog a M, Wa tan ab e K, I ss ik i Y, Kaw ada E 2001 The ef fec t s o f

re t rac t i o n f o r c es app l i ed t o t he an t e r i o r s egmen t on o r t h odo n t i c a r c h

w i res - c hanges i n w i re de f l ec t i on w i t h w i re s i z e . P res en t ed t o

s ou t he rn C a l i f o rn ia c om pon en t o f Edw ard H Ang le Soc ie t y . I n pres s.

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s c a n n e d b y U S T t e a m

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CASE NH

A 3 0 - y e a r- o l d m a l e p a t i e n t w i t h s e v e re a n t e r i o r c r o w d i n g

on m i ld C la s s 11 de n ta l ba s e s (ANB 5° ) . He h a d C la s s I

buc c a l s e gme n t s , a nd th i rd mo la r s ha d be e n p re v ious ly

extrac ted.

D

m

n

>

F i g .  9 . 3 3

There was a h igh-angle pa t te rn (MM angle 35°) . Lower arch

form was checked w ith t ransp aren t a rch form cards , and

assessed as approximate ly ovoid .

The up per r ight centra l inc isor was recorded a t 12 mm (o

APo line an d low er left central in ciso r at 5m m to APo line. It

was dec ided tha t the t rea tmen t goal wo uld b e to re t ract an d

al ign inc isors to a p lanned inc isor pos i t ion (I ' l l ' ) of

a pprox ima te ly 7m m to APo in the uppe r a nd 3 m m to APo in

the lower.

Trea tment mechanics were required to a l ign upper inc isors

approximate ly to the s ta r t ing pos i t ion of the upper le f t centra l

inc isor , or a l i t t le more dis ta l ly . In the lower a rch, the

objec t ive was to a l ign the lower inc isors to the s ta r t ing

pos i t ion of the lower r ight centra l inc isor . I t i s des i rable to

t rea t as many cases as poss ible wi thout extrac t ions , but in th is

case there was a need to make space avai lable for lower

F i g .  9 . 3 6

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inc isor a l ign men t and re t ra c t ion. Suff icient space cou ld not be

ob ta ine d f rom e xpa ns ion o r f rom e na me l re duc t ion . A

decis ion was therefore made to extrac t a l l f i rs t premolars , and

to t rea t th is h igh-angle case as a maximum anchorage case ,

us ing an upper pa la ta l bar and a lower l ingual a rch to support

too th move me n t s du r ing l e ve l ing a nd a l ign ing s t a ge s .

Bendbacks were used to ensure tha t the ends of the a rchwire

were com forta ble in the mo lar a rea , and to he lp co ntro l

me s ia l move me n t o f the a n te r io r l e e lh . (B e ndba c ks a nd

la c eba c ks a re no rma l ly c on t inu e d th rou gho u t to o th l e ve ling

and a l igning, unt i l the rec tangular s tee l a rchwire s tage , in

most cases.) Upp er and low er ovo id .0 16 IIANT wires were

placed. Standard .022 meta l brackets were used for opt imal

c on t ro l , a nd ba nds we re p l a c e d on a l l mo la r s a nd p re mola r s .

The ins tanding lower inc isors were not bracketed a t th is s tage ,

because no space was avai lable to pos i t ion them in the l ine of

the arch. Rubber s leeve was used for pa t ient comfort

m e a n t i m e .

F i g .  9 . 3 9

F i g .  9 .42

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f

>-  \  -

£

"www.allislam.net  

•  , *  . . .  j  -  •

; . .  j . .  • . . :  .

F i g .

  9 .34

S N A

\ SN B

V \ A N B

\ A-N FH

\

  Po-N

  F H

\ W I TS

)  G o G n S N

f  FM

( MM

\ 1 t o A -Po

- / 1 t o A -Po

7 7

7 2

5

- 3

- 1 5

3

4 2

3 2

3 5

1 2

5

) 1 t o M a x P l a n e ' 1 1 5

' 1 t o M a n d P l a n e /

9 4

m m

m m

m m

m m

m m

F i g .

  9 .35

F i g .

  9 .37

F i g .

  9 .38

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F i g .

  9 .40

F i g .

  9 .41

F i g .

  9 .43

F i g .

  9 .44

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■ • • '

Occlusa l v iews of the case a t the s ta r t of t rea tment . A lower

l ingual a rch and an upper pa la ta l bar were used a t the outse t

o f t r e a tme n t fo r a nc hora ge c on t ro l .

Sequ ential views at early adju stm en t v isits . At the first

adjus tment v is i t , the a rchwires were removed. The lower was

checked, and the ends were re -f lamed to re -soften them for

new bendbacks . Upper and lower lacebacks were s l ight ly

t ightened, to remov e the 1 mm or so of s lack wh ich typica l ly

develops be tween adjus tments in the ear ly s tages of t rea tment .

An uppe r .019 / .025 HANT wi re wa s p l a c e d w i th be ndba c ks .

The end s of the HANT' wire were f lamed and q ue nc he d before

placement .

At th is s tage , the case se t -up can b e c lear ly seen. As the up pe r

incisors start to level, a 0.5 mm vertical adjustment to the

upper r ight centra l inc isor bracket can be seen (Fig . 9 .52) .

This tooth was eventua l ly to be res tored and the s l ight

extrus ion was to fac i l i ta te the res tora t ive procedure . Double

uppe r mo la r tube s we re p l a c e d to a l low he a dge a r s uppor t .

Norma l c a n ine b ra c ke t s a re in u s e w i th -7° uppe r a nd -6°

lower torque . Cons idera t ion could be given to us ing 0°

-c.^

F i g .

  9 .45

F i g .  9 .48

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torque brackets in th is type of case to ass is t in keeping the

canine roots in cancel lo us bon e . At sub seq uen t v is its , the

lower .016 HANT wire was replaced w ith a .01 6 rou nd s tee l

wire and open coi l spr ings to recrea te space for lower inc isors .

Brackets adjacent to the open coil were tied with wire ties to

prevent ro ta t ions .

lhe c a s e a f t e r 9 mon ths o f t r e a tme n t . Uppe r l a c e ba c ks we re

d i s c on t inue d a nd the upp e r re c t a ngu la r HANT wi re wa s

replaced with a s tee l .01 9/ . 025 r ec tangu lar wire wi th soldere d

hooks and pass ive t iebacks . Enough space had been crea ted

for a l ignment of the ins tanding lower inc isors , and these were

bracketed. A lowe r .016 1IANT ovoid a rchw ire was used w ith

l a c e ba c ks a nd be ndba c ks to s t a r t mov ing the m in to the l i ne o f

the arch. I t i s not correc t to a t tem pt th is before en ou gh space

has been crea ted, as there is a r isk of prod  i na t ion a nd the n a

need for torque correc t ion la te r .

F i g .  9 .51

Fig. 9 .54

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F i g .

 9.46

F i g .

 9.47

HttBH^MHI

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F i g . 9.52

F i g .

 9.53

F i g .

 9.55

UST team

www.allislam.net

Sequent ia l v iews of the case a f ter 10 m on th s (Fig . 9 .56 ) , 13

mo nth s (Fig . 9 .57 ) , and 18 m on th s (Fig . 9 .5 8) .

At the 7-m onth ad jus tm ent v is i t , a rec tangu lar .0 19 / .02 5

IIANT lower wire (ovoid sh ape ) had been placed, and a t th e

10-m onth adjus tm ent v is i t , a rec tan gular .01 9/ .0 25 stee l lower

wi re (ovo id s ha pe ) w a s pos s ib l e , w i th s o lde re d hoo ks a nd

pass ive t iebacks . At th is s tage , cons idera t ion was given to

producing an individual ized arch form (1AF) for th is pa t ient ,

but it was fel t tha t th e nor ma l ovo id form was ve iy c lose to

the s ta r t ing lower a rch, an d could therefore be used. N orm al

space c losure was carr ied out wi th ac t ive t iebacks , but

diff icul ty was experien ced in c los ing the upp er r ight pre in olar

space . This is unu sual . In a lm os t a l l t rea tm ent of chi ldre n, t he

spaces wil l c lose uneventful ly us ing s l id ing mechanics and

act ive t iebacks . In a few adul t t rea tments , i t may be found tha t

spaces a re s low or d i ff icul t to c lose with the normal

mechanics , and there may be a need to use a rec tangular wire

with space-c los ing loops or a

  1

  Iycon® device.

Sequent ia l v iews of the r ight s ide showing space c losure with

the Hycon® device . No obs tac les to space c losure were evident ,

and a l te rna t ive mechanics such as t iebacks with two modules ,

o r a loope d a rc hwi re we re c ons ide re d . A de c i s ion w a s ma de to

use the I Iycon® device from Eden ta . This ha s been used

successfully by one of the authors for 4 years in selected cases.

Sequent ia l occ lusa l v iews showing space c losure .

Approximate ly   1  mm of s pa c e c los u re c a n be a c c ompl i s he d

per mo nth . This device prov ides a very short - ac t ing bu t s t ron g

force tha t essent ia l ly overcomes any fr ic t ional concerns . I f

overdone , however , i t wi l l lead to s ignif icant a rchwire

deflec t ion, which should be avoided. The Hycon® device , l ike

pala ta l expanders , d is t rac t ion os teogenes is screws , and some

molar d is ta l iz ing devices , requires d i l igent pa t ient

coopera t ion to ensure success .

Fig. 9.56

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The f ina l se t t l ing s tage of t rea tment , a f te r 20 months . Finishing

and de ta i l ing was not a separa te and lengthy s tage of mechanics

in th is case ; as a resul t of goo d early t rea tm ent m an ag em en t ,

only careful se t t l ing was needed before proceeding in to

re tent ion. A .016 round HANT wire was used in the lower a rch,

with ovoid arch form. In the upper a rch, a .014 round sec t ional

wire was place d from lateral inc isor to lateral incisor . Tee th h ad

been extracted, and therefore figure-8 ligature wires were

placed across the extrac t ion s i tes to hold them c losed.

The .014 s e t t l i ng w i re s we re a c c ompa n ie d by the us e o f

l ight vert ica l t r iangular e las t ics and good se t t l ing occurred. In

cases with accura te bracket p lacement , few e las t ics need to be

used in th is way. I t was dec ided to keep a l l bands and

brackets on the tee th during se t t l ing, so tha t i f unwanted

changes occurred, these could be correc ted. The pa t ient was

seen a t approximate ly 2-week in terva ls during the se t t l ing

phase. Elastics were worn full t ime for the first 2 weeks, then

at night for a period of 2 weeks.

F i g .

  9 .65

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Fig . 9 .57

Fig .

  9.58

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Fig . 9 .66 Fig . 9 .67

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www.allislam.net

Fig. 9.69

Fig .  9.70

Fig. 9.72

Fig.  9.73

N.H. Final

32.9 years

3/28/00

A-N

Po-N

SN A

SN B

A N B

F H

FH

W I T S

G o G n S N

FM

M M

Z 7 8

/ 7 3

/-  5

-2

-13

4

/ 4 1

/ 3 1

Z 3 3

m m

m m

m m

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Fig .  9.75

P a l a t a l P l a n e &

P a l a t e C u r v a t u r e

N.H.Begin

N.H.Final

Fig.

  9.78

Fig .

  9.79

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1 t o A -Po

1 t o A-Po

1 t o M a x P l a n e

1 t o M an d P lane .

7

3

104

' 91

m m

m m

M a n d .

  S y m p h a s i s

& M a n d . P l a n e

N.H.Begin

N.H.Final

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CASE M O T

A fe ma le f i rs t p re m ola r e x t ra c t ion c a s e , a ge d 11 .6 ye a rs a t

the s t a r t o f t r e a tme n t , w i th C la s s

  11

  s ke le t a l ba s e s (ANB 7° )

on a n a ve ra ge a ng le pa t t e rn (M M 28° ) .

Fig .  9.80

Denta l ly , there was anter ior and pos ter ior c rowding with a

lack of space for perm an ent c anine s . Th ere was uppe r an d

lower inc isor c row ding with rota t ion s . Arch form w as assessed

as ovo id. It was felt that fou r first pr em ola rs sh ou ld be

extrac ted in order to achieve a s table resul t wi th good profi le

and hea l thy periodonta l t i s sues .

Fig .

  9,83

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Fig. 9 .86

After f i rs t premolar extrac t ions , the f i rs t molars were banded,

and s tandard meta l brackets were placed in the lower a rch.

C om me n c e m e n t o f uppe r a rch b ra c ke t ing wa s de la ye d un t i l

a f te r e rupt io n of the upp er second prem olar s . Th e in i t ia l

lower a rchwire w as .016 IIANT , an d he re the case is seen af te r

2 months of t rea tment wi th .020 round s tee l wires in p lace .

Lower lacebacks were placed to control and s l ight ly re t rac t the

canines .

Fig. 9.89

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M.O. Beginning

11.6 years

3/7/97

F i g .

  9.81

A - N

Po-N

S N A

S N B

A N B

F H

F H

W I T S

G o G n S N

8 6 °

7 9 °

'.

  7 °

4

  mm

-5

  mm

0  mm

3 6 °

F M

 /

  2 7

 •

M M

1 t o A - P o

1  t

1

  to

  M a x

> A-Po

Planer

1  to  M a n d P l a n e

28

 •

7  mm

3  mm

111

 •

9 4 "

F i g .

  9.82

F i g .  9.84

F i g .

  9.85

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F i g .  9.87

F i g .

  9.88

F i g .

  9.90

F i g .

  9.91

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■ ■ ■ M M

u>

>

n

m

n

i

-

O

c

m

>

D

A lower lingual arch and an upp er palata l bar were p laced to

suppor t anchorage dur ing the ear ly s tages o f too th al ignment .

Wh en u p p er seco n d p remo l a r s were c l o se t o fu l l e ru p t i o n , t h e

s ix u p p er an t e r i o r tee t h were b rack e t ed an d a . 0 1 6 HA NT wi re

was p laced wi th passive co i l sp r ings to p ro tect the long buccal

spans of the archwire. Lower lacebacks were d iscont inued at

t h is s t age , a s t h e can i n es were b e g i n n i n g t o m o v e aw ay f rom

the lateral incisors.

Sequent ial v iew of the r igh t s ide o f the t reatment af ter 7

mo n t h s , 1 1 mo n t h s , an d 1 5 mo n t h s o f t r ea t men t . A t 7

mo n t h s , u p p er an d l o wer r ec t an g u l a r  I  IANT wires are in

p lace, and the upper can ines have ret racted a l i t t le away f rom

the la teral incisors , as the lower can ines have moved d is tal ly .

This is accep tab le dur ing too th level ing and al ign ing , a nd

p ro v id es a smal l am o u n t o f ad d i t i o n a l an ch o rag e .

Subsequent ly , upper and lower s teel rectangular wires were

p laced , wi th l igh t Class I I e las t ics dur ing space closure. Passive

F i g .

  9 .92

F i g .  9 .9 4

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t iebacks were p laced to main tain the space closure.

After 2 years o f act ive t reatment , set t l ing was commenced .

Here, the case is seen p r io r to app l ian ce rem oval . Ligh t

t r iangular e las t ics we re used in the mo lar and pre mo lar

reg ions and the pat ien t was checked at 2 -weekly in tervals .

F i g .  9 .9 7

F i g .

  9 . 1 0 0

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Fig. 9 .95

Fig. 9 .96

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F ig .  9 .98

Fig. 9 .99

J

F i g .

  9 . 1 0 1

F i g .  9 .102

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The case after appliance removal. Active treatment time was

slightly extended lo 27 months because of delays early in the

treatment whilst awaiting the eruption of premolais.

Normal retention, with lower retainers extended onto the

lower second prem olars. The post-treatmen t radiographs

suggest there is adequate space for eruption of the third

molars, and confirm a good relationship between the upper

canine roots and upper second premolar roots.

Post-treatment facial profile was pleasing, and the

cephalomelric measurements were close to normal.

F i g .

  9 . 1 0 6

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F i g .

  9 .109

F i g .

  9 .112

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M . O . B e g i n

M . O . F in a l

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F i g .  9 .1 0 4

Fig.

  9 .105

F i g .  9 .1 0 7

Fig .

  9 .1 0 8

S N A 8 5 °

S N B Z 8 1 •

A N B /  4 °

A - N F H 2 m m

Po-N FH O m m

W I T S 0 m m

G o G n S N   /  34 °

F M 2 6 "

M M 2 8 °

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u

Fig.  9.110

P a l a t a l P l a n e &

P a l a t e C u r v a t u r e

M.O.Begin

LVJ..O .•'::••-vi I!

F i g .

  9 . 1 1 4

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1 t o A -Po 6 m m

1 t o A -Po 3 m m

1 t o M a x P l a n e 1 1 3 °

1 t o M a n d P l a n e / 9 2 °

M a n d .

  S y m p h a s i s

& M a n d . P l a n e

M.O.Begin

M.O.Final

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Problem

Finishing the case

CHAPTER 10

Introduction

  280

Horizontal considerations  282

Co ordin at ion of tooth f it 282

Establishing correct tip of the anterior and

poster ior tee th 283

Providing adequa te inc isor torqu e 284

Man agem ent of too th s ize d iscrepancies 285

Con tro l l ing ro ta t ions 285

M aintai ning the closure of all spaces 286

Horizonta l overcorrec tion 286

Vertical considerations  288

Correct crown lengths, marginal ridge

re la t ionships , and contact poin ts 288

Final m ana gem ent of the curve of Spee 288

Vertical overcorrection - deep-bite and open-bite

cases 289

Dynamic con s idera t ions

  2 9 1

Establishing centric relation and checking

funct ional mo vem ents 291

Check ing for t emporo ma nd ibu la r jo in t

dysfunction 292

Cephalometric and esthetic considerations

  293

The final stage of finishing - settling the

case 294

Finishing to ABO requirements 296

Case MB A high angle non-extraction

  case

  which

required upper incisor torque and lower incisor

enam el reduction 298

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Transverse considerations  289

Arch form  289

Archwire coordina t ion 289

Establ ish ing poster ior torque 290

Transverse overcorrection 291

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INTRODUCTION

During th is las t s tage of t rea tment , f in ishing and de ta i l ing, i t

i s important to cont inue to focus on t rea tment goals . As

stated at the outset, in the preface, these are as follows:

Condyles in a sea ted po s i t ion - in centr ic re la t io n

Relaxed hea l thy muscula ture

A 's ix keys ' (-lass I occlusion

Idea l func tiona l m ove me n t s - a mu tua l ly p ro te c t e d

occlus ion

Periodonta l hea l th

Best possible esthetics.

Pa t ients t rea ted with the s tandard edgewise appl iance

re qu i re d a s ign i f i c a n t a moun t o f w i re be nd ing du r ing the

finishing stage of treatment (Fig. 10.1). In the earlier s tages of

t rea tment , the tee th were moved in to a reasonable pos i t ion

wi th in e a c h a rc h a nd the a rc he s we re b rough t in to c lo s e

p rox imi ty to one a no the r . The n the t e d ious work o f de ta i l i ng

began, and the bes t wire benders achieved the bes t resul ts .

The re fo re , d i s c us s ing f in i s h ing a s a n inde pe nde n t s t a ge wa s

a ppropr i a t e , be c a us e i t wa s a l e ng thy a nd c ha l l e ng ing s t a ge .

Because of the bui l t - in fea tures of the preadjus ted

a pp l i a nc e (F ig . 10 .2 ) , a nd the ma jo r e mpha s i s on b ra c ke t

p la c e me n t , mov ing t e e th to the i r f in i s he d pos i t ions be g ins a s

soon as the brackets have been placed and the f i rs t a rchwires

tied in. There is a gra du al flow tow ard t he finishing stage,

with less work required a t the end. Finishing and de ta i l ing, as

described in the auth ors ' fi rs t boo k, is therefore n o lon ger a

s e pa ra t e a nd l e ng thy s t a ge o f me c ha n ic s , bu t more a

re wa rd ing ou tc ome fo r good ma na ge me n t o f the c a s e , e a r l i e r

in the t rea tment .

F i g .

  10.1

  I t was dif f ic ult to achieve ideal results using t he

standard edgewise t rea tment sys tem because o f the la rge

amoun t o f ted ious de ta i l i ng w h ich w as requ i red .

F i g .  1 0 .2

  T he in t roduc t ion o f the p read jus ted b racke t system

in the 1970s made achievement of ideal results easier.

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Problem

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For example, the m ore closely the appliance matches the

mechanics of the orthodontist, the less work is required in

finishing. The better the brackets are placed and repositioned

as needed, (he less work is required in finishing. The greater

the attention paid to accurate arch form and archwire

coordination, the less work is required in finishing. The less

that force levels overpower the appliance system, moving

teeth to inappropriate positions, the less work is required

during finishing. And [he list goes on! In other words, there is

a gradual and progressive movement toward finishing, rather

than an abrupt, clearly defined treatment stage (Fig. 10.3).

Therefore, probably the greatest advantage of the preadjusted

appliance is thai il lets us redefine finishing and detailing as:

Th e conection  of enors made prior to  finishing and  detailing

over correction a s needed an d settling o f the case.

This chapter will review and summarize the horizontal,

vertical, and transverse factors that allow the orthodontist to

arrive at a well-finished case. The too th mo vem ents during

finishing and detailing are minor, and are difficult to record

with photographs. Therefore, the chapter relies on text, raiher

than illustrations, to explain the necessary procedures.

During the closing stages of treatment attention needs 10

be given lo the following considerations:

• H o r i z o n t a l

• Vertical

• Transverse

• Dynamic

• Cephalom etric and esthetic.

F i g .

  1 0 . 3

  Fu r the r im prov em ents i n t ec hn ique hav e bec om e

poss ib le us ing the MBT™ bracket sys tem and HANT wi res .

F in ish ing and de ta i l in g are no longe r a separate and leng thy

s tage of mechanics , prov id ing the case has been wel l managed

ear l i e r i n t he t r ea tm en t .

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HORIZONTAL CONSIDERATIONS

1/1

-z.

o

H

I

m

n

>

t /1

Coordinat ion of tooth f i t

A

 major finishing consideration in the horizon tal plane is the

coordination of tooth fit in the anterior and posterior areas.

The authors find that the anterior and posterior teeth fit well,

with little or

  no

  adjustment, in approximately 2 0% of cases

(Fig. 10.4). However, in approximately 60% of cases

(Fig. 10.4), as the finishing stage approaches, it becomes clear

that the crowns of the upper anterior teeth do not occupy

enough space, relative to the crowns of the lower anterior

teeth. The evidence may be seen in the following situations:

• Cases where poster ior space closure is difficult in the up per

arch while maintaining the correct amount of overjet

(3-4 mm).

• Cases where the overjet is correct, but th e buccal segmen ts

remain in a slight to moderate Class

 11

  position.

/ 20%

20 %

  /

60%   1

1  " "

~2  Ma ndibu lar excess 60%

"2   M axi l lary excess 20 %

t z m

  G o

°

d

 fit 2o%

Tooth s ize coord inat ion

Fig .

  10.4 Tooth size coordination.

• Cases where complete space closure in the upper anterior

segment is difficult w hile attem pting to main tain the

correct amount of overjet.

In approximately 20% of cases (Fig. 10.4), the authors find

an excess of upper anterior tooth substance, relative to the

lower. In these cases, the crowns of the teeth in the upper

anterior segment are disproportionally larger than the crowns

of the teeth in the lower anterior segment, and the patient

shows some excessive overjet when the posterior segments are

in a Class

 1

  relationship. This is seen in the following

situations:

Upper and lower

teeth do not fit'

Torque

Tooth size

Fig ,

  10.5

In patients with large upper incisors

In some Class III cases where upper incisors are proclined

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forward and lower incisors are retrodined.

These patients can be easily managed during finishing by

carrying out some ename l reduction in the upper a nterior

segment and then closing the residual space.

The challenge, then, is dealing with the 60 % of cases that

show a relative shortage of tooth mass in the u pper anterior

segment. In the horizontal plane, this difficulty relates

primarily to the factors of tip in the anterior teeth, incisor

torque, and tooth size (Fig. 10.5). Each of these will be

discussed below.

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Establ ishing correct t ip of the anter ior

and poster ior teeth

T ip  is on e of the s t reng ths of the preadjus ted appl ia nce ,

espec ia l ly when twin brackets wi th adequate width are used.

Nearly full expression of the bracket tip is expressed with

re la t ive ly l i t t le e ffor t , and t ip bends are normal ly not needed.

W i th t he s t a nda rd e dge wis e a pp l i a nc e , howe ve r , s e c ond

order ( t ip) bends were placed in the a rchwires for two

reasons . Firs t , to properly move tee th re la t ive to the 0° of t ip

in the bracket and, second, to compensa te for the heavy forces

used to mov e tee th . Therefore , u nless overp ow ering forces a re

us e d du r ing t r e a tme n t w i th the p re a d jus t e d a pp l i a nc e , t he re

should be l i t t le need to modify the l ip measurements

ob ta in e d by Andre ws in h i s s tudy o f the non -o r tho don t i c

no rma l mode l s . Th i s ha s be e n the c ho ic e o f the a u tho rs , a nd

on ly minor t i p mod i f i c a t ions we re ma de whe n de ve lop ing the

MBT™ appliance system, relative to (he research figures.

Bracket t ip is on e of the ma in fac tors tha t inf luen ce the

a m ou n t o f s pa c e oc c up ie d by e a c h too th . Th i s in tu rn

influences the way the upper tee th f i t wi th the lower tee th .

When us ing anter ior brackets wi th prec ise ly Andrews ' or ig ina l

t ip measurements , a to ta l of 40° of t ip is p laced in the upper

anter ior segment , and only a to ta l of 6  °  in the lower anter ior

segm ent (Fig . 10.6) . The resul t ing 34 ° of ' t i p d i ffe rent ia l '

he lps to increase the s ize of the upper anter ior segment and

de c re a s e the s i z e o f the lowe r a n te r io r s e gme n t . Th i s he lps t o

a c h ie ve impro ve d too th f it w i th in the 60% grou p de s c r ibe d

a bove .

The shape of inc isor c rowns needs to be assessed during

finishing. Tipp ing inciso r cro wn s, wh ich are barrel or

t r iangular shaped, wi l l have l i t t le e ffec t on the arch length

occupied (Fig . 10.7) . However , barre l -shaped crowns are

fortunate ly ra re . Triangular-shaped crow ns wil l norm al ly be

reshaped to a more rec tangular form, by the or thodont is t , for

es the t ic reasons . So crown shape is se ldom an issue , except a t

Total 40"

Total 6

3° 0° 0" 0

D

  0" 3°

F i g .  10 .6 The t i p d i f f e re n t i a l be tw een upper and l ow e r

an te r i o r s egm ents he lps t o ac h iev e im prov ed to o t h f i t w i t h i

t he 60% g roup o f pa t i en t s w here t he c row ns o f t he upper

an te r i o r t ee th do no t oc c upy enough s pac e , r e la t i v e t o t he

c row ns o f t he l ow er an te r i o r t ee th .

Triangular

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t he t r e a tme n t p l a nn ing s t a ge .

W he n de s ign ing the M B T

IM

  uppe r p re mola r b ra c ke t s , t he

t ip was s l ight ly modif ie d , re la t ive to the research f igures . Ih e

chan ge was from 2" to 0° of t ip . This was to he lp too th f it ,

a nd t o pos i t ion the uppe r p re m ola r c rowns in a s l igh t ly m ore

upr igh t pos i t ion , w h ic h i s mo re towa rd a C la ss  1 pos i t ion

from a starting (Mass II malocclusion. The MBT

IM

  lower

bicusp id b rackets have 2° of t ip , wh ich is the research f igure ,

and th is inc l ines the m to ward a Class I pos i t ion from a

s tar t ing Class II re la t ionship .

Molar t ip of 5° in the upper and 2° in the lower is

required. These t ip va lues pos i t ion the molar cusps para l le l to

the occ lusa l p l ane , w hich is correc t . This t ip is achieved by

us ing MBT™ 0° brackets on a l l molars , and plac ing the bands

para l le l to the cusp t ips (p p 66 & 67) . This pos i t io nin g a l lo ws

the molars to se t t le in to an idea l Class I re la t ionship .

Parallel sided

Barrel shaped

F i g .  10 .7 The shap e of inc isor crown s needs to be assessed

dur ing f i n i s h ing and s e t t l i ng .

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Providing adequate incisor torque

Torque c on t ro l i s t he we a kne s s o f the p re a d jus t e d a pp l i a nc e

sys tem, and any sys tem which is based on the edgewise

bracket . There a re three fac tors , and because of these , there

does not seem to be a s ingle se t of torque va lues tha t wi l l

solve the needs of a l l pa t ients :

1

Approximate ly a 1-mm segment of rec tangular s tee l wire is

placed in a bracket of about the same dimens ion. This is

required to carry ou t a ra ther d i ff icult to oth m ov em en t ,

wh ic h invo lve s mov ing a n e n t i r e po r t ion o f the roo t

through a lveolar bone (Fig . 10.8) .

A lul l -size wire is no rm al ly not used becau se such wires do

not s l ide e ff ic ient ly through the pos ter ior bracket s lo ts . In

order for s l id ing mechanics to be effec t ive , the authors use

a .019 x .025 wire in the .022 s lo t . This reduc es the

effec t iveness of the rec tangular wire , re la t ive to torque

control (Fig . 10.8) .

3 .  The uppe r a nd lowe r a n te r io r to rque ne e ds o f pa t i e n t s va ry

greatly.

With mos t Class I and Class II pa t ients , ther e is a ten den cy

for upper inc isors to be re t roc l ined and lower inc isors to be

procl ined. In Class III cases , the oppos i te tendency occurs .

Because the m ajority of pat ien ts are eith er Class I or Class II

in ma ny p ra c t i c e s , t he ge ne ra l t e nde nc y in o r thodon t i c

a pp l i a nc e s i s t o p l a c e a dd i t iona l pa la t a l roo t t o rque in the

upper inc isor brackets and addi t ional labia l root torque in the

lower inc isor brackets .

W he n de s ign ing the M B T™ s ys te m, the a u tho rs c hos e to

add an addi t ional 10° of pa la ta l root torque to the upper

centra l inc isor brackets , an addi t ional 7° of pa la ta l root

to rque to the upp e r l a te ra l i nc i s o r b ra c ke t s , a n d a n a dd i t ion a l

5° of labia l root torque to the lower inc isor brackets . This

addi t i onal to rque , re la t ive to the research f indings, i s he lpful .

A .019/.025 rectangular wire

with 2 mil radii will have 10°

of slot play in  the .022 slot

Up

 t o 20

r

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However, it i s f requent ly necessary to a lso add tor que be nd s

to the rec tangular s tee l wire in the inc isor regions . In mos t

Class II cases and many Class I b imaxi l la ry protrus ive cases , i t

i s be nef i ci a l t o a dd a n a dd i t iona l a m ou n t o f pa la t a l ro o t

to rque to the uppe r a rc hwi re (up to 20° ) a nd a n a dd i t iona l

1 0 - 1 5 "

  of labia l root torque to the lower a rchwire (Fig . 10.9) .

In genera l , the torque fea tures in the MBT™ brackets , and

a ppropr i a t e to rque be nds in the a rc hwi re s , whe re ne c e s s a ry ,

he lp to ma ke the uppe r a n te r io r s e gme n t b igge r a nd the lowe r

a n te r io r s e gme n t s ma l l e r , t hus improv ing too th f i t w i th in the

6 0 %

  grou p (C a s e T C , p . 194) .

10°to 15°

F i g .

  1 0 .8

  The pread jus ted app l ian ce is no t e f f ic ien t a t

con t ro l l i ng to rque ow ing to the sma l l segmen t o f rec tangu la r

s tee l w i re and a lso ow ing

  to b ra c k e t

  ' s lop ' . I t is f requent ly

necessa ry to a dd to rq ue b ends t o the rec tangu la r s tee l w i res in

the inc isor reg ions.

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Management of tooth size discrepancies

Tooth s ize i s actual ly the ' seven th key ' lo normal occlusion .

I t i s c l ea r t h a t t h e An d rews ' n o n -o r t h o d o n t i c n o rm al mo d e l s

had balanced too th s ize. I f no t , there would have been ei ther

sp ac i n g i n o n e a r ch o r c ro wd i n g i n t h e o p p o s i n g a r ch .

As s taled abov e, i t i s co m m on to see a lack of too th ma ss

in the upper an ter io r segment relat ive to the lower an ter io r

segm ent . To oth s ize d iscrepa ncy f requently con t r ibu te s to the

s i t u a t i o n . T h e mo s t co m m o n an t e r i o r t o o t h s ize d i sc r ep an cy

consis t s o f smal l la teral incisors in the upper arch and /or large

lateral incisors in the lower arch . In the buccal segments ,

smal l upper seco nd prem olar s f requent ly con t r ibu te to the

too th s ize d iscrepancy .

Evaluat ion of too th s ize d iscrepancy can be carr ied ou t by

using the Bol ton analysis .

1

  T o o t h s i ze d i sc r ep an cy m ay b e

corrected ei ther by reducing too th mass in one arch wi th

in ter -prox imal enamel reduct ion (usual ly the lower incisors)

an d / o r b y ad d i t i o n o f t o o t h mass wi t h r e s t o ra t i v e ma t e r i a l s i n

the op po sin g arch (usual ly the upp er la teral incisors) .

I t i s more common to f ind an excess o f too th substance in

the lower arch. If the Bolton analysis confirms this, i t is often

advisab le to carry ou t in ter -prox imal enamel reduct ion in the

lower an ter io r reg ion in the in i t ia l s tages o f t reatment (Case

MS,  p . 2 3 6 ) . On l y mi n i m al am o u n t s o f t o o t h m ass sh o u l d b e

remo v ed f ro m t h e u p p er an t e r i o r seg men t , ea r l y i n t r ea t men t .

As the f in ish ing s tage of t reatm ent i s app roa che d , th e relat ive

too th mass in the upper an ter io r segment can be evaluated . I f

there i s an excess o f upp er a n ter io r too t h mas s as a resu l t o f

l o wer t o o t h mass r ed u c t i o n , t h en s t r i p p i n g p ro ced u res can b e

carr ied ou t in the upp er an ter io r segm ent . I f ena me l reduct io n

i s d o n e i n t h e u p p er a r ch t o o ea r l y in t r ea t m en t , sp ac i n g may

resu l t , which can on ly be corrected by the add i t ion of

b o n d i n g mat e r i a l .

Contro l l ing ro ta t ions

Rota t ion con t ro l is an im por tan t aspect o f f in ish ing and

d e i a i l i n g . F o r t u n a t e l y , t h e i n -o u t co mp en sa t i o n b u i l t i n t o t h e

p read j u s t ed ap p l i an ce , co m b i n e d wi t h co r r ec t b r ack e t

pos i t ion ing , i s m ost effect ive in con t ro l l i ng ro tat i ons . Th e

most obvious example of th is i s the 10° o f ro tat ion thai i s

i n t ro d u ce d i n t o t h e b rack e t s o f th e u p p er m o l a r s , an d t h e 0 °

of ro tat ion p laced in the lower molars . Th is com bin at i on i s

most benef icial in a l lowing the upper molars to occlude

prope r ly in a Class I pos i t ion w i th the lower m ola rs .

I t can b e benef icial in C lass I an d C lass II cases to p lac e

u p p e r p re i n o l a r b r ack e t s ap p ro x i m at e l y 0 : 5 m m l o t h e mes i a l .

T h i s a l l o ws t h e b u cca l cu sp s o f t h e u p p er p remo l a r s t o ro t a t e

d is tal ly toward a Class I pos i t ion , and th e palatal cusp s o f

these teeth lo ro tate mesial ly so that they occlude more

accurate ly in to the fossae of the lower arch . I f an te r io r teeth

show ro tat ion at the beg inn ing of t reatment (F ig . 10 .9) , i t i s

benef icial to p lace the b racket s l igh t ly in the d i rect ion of the

ro tat ion to aid in thei r correct ion (p . 61 ) . Also , i i i s benef icial

to p lace lower can ine brackets s l igh t ly to the mesial . Th is

ro tates the mesial aspect lab ial ly and prov ides bet ter con tact

wi th the d is la l aspect o f ihe lower la teral incisors .

F i g .  10 .9 Ac c ura te b rac ke t pos i t i on ing a t t he s ta r t o f

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t r ea tm en t c an as s i s t i n r o ta t i on c on t ro l du r i ng t he f i n i s h ing

stages.

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  M ain tain ing the c losure of al l spaces

-n It is importan t to keep spaces closed durin g the finishing

stage of treatment, particularly in extraction cases. This can be

I accomplished with passive wire tiebacks (Fig. 10.10) whe n

rectangular wires are in place, and with lacebacks from molars

to cuspids when light wires are in use. In extraction cases,

during the settling stage, figure-8 ligature wires (Fig. 10.11)

,-, should be placed across the extraction site to keep them

r$ closed. Also, in any othe r areas where space closure was

sornewha! difficult, figure-8 ligature wires or light elastic

thread should be used to maintain space closure during

settling. Carrying out these simple procedures eliminates the

troublesome problem of spaces opening in the finishing

stages of treatm ent.

F i g .

  10 .10 Spaces may be kept c losed a t the rec tang u la r w i re

stage by using passive wire t iebacks.

Hor izonta l overcorrec t ion

It is often necessary to consider horizontal overcorrection of

Class II and Class III cases. During the finishing stages of

treatment, it is important to fully correct the A/P position of

the dentition using methods such as Class II or Class III

elastics, or headgear, for example. After correction has been

completed, then these methods of tooth movement can be

discontinued or worn on a part-time basis. The patient may

then be observed for a period of 6  to 8 weeks. If the case

appears to b e stable, the appliances can be removed. If not,

these cases can be horizontally overcorrected.

In Class II cases, the anterior teeth can be brought to an

edge-to-edge position and held for approximately 6 to 8

weeks (Fig, 10 .12). After this, elastics can be discon tinued or

worn at night only, to see how the ca.se is settling.

A Class HI case can be horizontally overcorrected by

producing 2-3 mm of additional overjet, and this may then

be held or observed in a similar manner to Class II cases.

Even if these overcorrection techniques are carefully

followed, problem s can occur during retention. These can be

due to late aberrant growth, or to re-established tongue or

finger habits, for example. These concerns need to be

explained to patients, and observation at regular intervals

during retention is in their best interest.

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F i g .

  1 0 . 1 1 Wh e n t r e a t i n g p r e m o la r e x t r a c t i o n cases , f i g u r e - 8

l iga tu re wi res shou ld be p laced across the ex t rac t ion s i te dur ing

the se t t l ing s tage to p revent spaces f rom open ing .

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F i g .

  1 0 . 1 2 A

  a n d

  B

  Th is low- ang le Class 11/1 ma locc lus ion was mana ged w i th ou t head gear , bu t inc lude d the ex t rac t ion o f uppe r

second perma nen t mo lars . Standard meta l b racke ts we re used. The case is seen here be fore t re a tm en t , and a f te r p lacem ent o f in i t ia l

. 0 1 5 m u l t i s t r a n d u p p e r a n d l o we r a l i g n i n g w i r e s .

F i g .  1 0 . 1 2 C

  a n d

  D

  Upper an d lower rec tangu la r s tee l w i re s an d Class I I e las tics we re used fo r ov er je t cor re c t ion . W he n f in ish ing th e

case, a .014 rou nd w i re was used in th e upp er a rch , w i t h l ig h t C lass I I mechan ics to ensure over cor re c t ion o f the o ver je t and

o ve r b i t e .

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F i g .

  1 0 . 1 2 E

  a n d

  F

  He r e t h e ca se is se e n p r i o r t o b a n d r e m o va l , a f t e r a sm a l l a m o u n t o f se t t l i n g h a s o ccu r r e d w i t h t h e a p p l i a n ce s i n

p lace . F ina l ly , the case is seen 18 mo nths a f te r band re mo va l , w i t h go od se t t l ing an d imp rove d ora l hy g ien e.

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VERTICAL CONSIDERATIONS

C o r re c t c r o w n l e n g t h s , m a r g i n a l r i d g e

re la t i onsh ips , and con tac t po in ts

Correct ion of ver t ical crown po si t ion s , marg inal r idge

re l a t i o n sh i p s , an d co n t ac t p o i n t s sh o u l d b e co mp l e t ed d u r i n g

the rectangular HANI 's tage of t reatment . I f th is i s no t done,

t h ese co r r ec t i o n s mu s t b e m ad e d u r i n g t h e f i n i sh i n g an d

detai l ing s tage of t reatment , shor t ly before b racket removal .

This does no t ensure s tab i l i ty o f ver t ical too th posi t ions . I t i s

much bet ter fo r s tab i l i ty to a l low these relat ionsh ips to be

correct for 1 to 2 years before bra cket rem ova l. Correct b racke t

plac em ent a t an early stage is cri t ical for stabil i ty.

The chap ter on bracket p lacement (p . 62) d iscusses in

detai l the technique used by the au thors fo r p roper ver t ical

b racke t p l acem en t . T h e ch ar t s h av e b een u sed fo r 6 y ea r s an d

have proven to be most ef fect ive. They have reduced the need

for b racket reposi t ion ing by approximately 50%, and have

enhanced the ef f ic iency of t reatment and the s tab i l i ty o f

results.

As d iscussed ear l ier , uppe r can ine s and lower f i rs t

p remolars f requent ly have long and po in ted cusps, and for

su ch t ee t h t h e b rack e t p o s i t i o n i n g sh o u l d b e ap p ro x i mat e l y

0 .5 m m m o re g i n g i v a l . T h i s wi ll m i n i m i ze t h e n e ed o f se t t l i n g

or detai l ing bends at the end of t reatment (F ig . 10 .13) .

The poste r io r f igures on the b ra cket - posi t io n ing char ts

( p .  63) are based on averages , fo r teeth wi th no rm al marg inal

r idges , in correct posi t ion . However , fo r poster io r teeth wi th

cu sp h e i g h t s wh i ch v a ry f ro m t h e n o rm, o r wi t h ab n o rmal

marginal ridges, bracket posit ions may need to be sl ightly-

modif ied to accommodate these d i f ferences . The need for th is

can easi ly be observed at the rectangula r I IAN T stage of

t reatment . Brackets can then be reposi t ioned to correcl the

marg inal r idges at that l ime.

I t is so m et i m es n ecessa ry t o mak e m i n o r a r ch w i re b en d s i n

the f in ish ing s tages o f t reatment , to correct improper ver t ical

b racke t p o s i t i o n , b u t t h ese p ro ced u res a r e so m ew h at u n s t ab l e

F i n a l m a n a g e m e n t o f t h e c u r v e o f S p e e

Low-angle cases

In most average- to low-angle cases, i t is beneficial to level the

en t i re curve of Spee. This sho uld i nclud e p lace m ent o f

b rack e t s o r b an d s o n seco n d m o l a r s t o co m p l e t e t h e p ro cess .

I f the curve of Spee i s no t fu l ly corrected in these cases , the

lower incisors wi l l be posi t ioned more g ing ival ly on the

palatal surface of the upper incisors . Th is may make i t

d i f f icu l t o r impossib le to complete f inal space closure in the

upper arch and to keep these spaces closed . I f the b i le i s

opened proper ly and the curve of Spee i s level , i t i s then

possib le to complete space closure in the t ipper arch wi th

stab i l i ty . Upper b i te-p late retainers should be considered in

cases t h a t sh o w a t en d en cy fo r b i t e d eep en i n g d u r i n g

reten t ion . This type of re lapse can be accompanied by spacing

in the upper arch and /or crowding in the lower arch .

High-angle cases

I  l i g h -an gl e cases wi t h o p en -b i t e t en d en c i es m u s t b e h an d l ed

carefu l ly . In these cases , i t i s impor tan t to leave some curve of

Spee in the back of the arch , par t icu lar ly in the second molar

area. This a l lows th e b i te to remain closed an ter io r ly . I f the

back of the curve of Spee is leveled in such cases, there is a

great r i sk o f an ter io r open b i te . For pat ien ts near the end of

the g rowth per iod , i t may be d i f f icu l t o r impossib le to c lose

t h i s an t e r i o r o p en b i t e .

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near the end of treatment. It is far better to correct vertical

bracket posi t ions much ear l ier in t reatment .

-:v

F i g .

  10.13 Cor rec t ver t ica l bracket po s i t ion ing w i l l m in im ize

the need fo r de ta i l i ng bends a t t he end o f t r ea tm en t .

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V e r t i c a l o v e r c o r r e c t i o n - d e e p - b i t e a n d

open-b i te cases

I t i s benef icial to in t rodu ce som e overco rrect ion in deep-b i le

and op en- b i le cases . Th is p rocess beg ins wi th in i t ia l b racket

p l acem en t . B racke t s o n t h e an t e r i o r t ee t h can b e p l aced

0 .5 m m mo re g in g i v a l i n o p en -b i t e cases an d 0 .5 m m mo re

incisal in deep-b i te cases (p . 65) . Th is g reat ly ass is ts in th e

o v erco r r ec t i o n p ro cess .

In deep-b i te cases , level ing of the curve ofSpee wi th f la t

s teel rectangular archwires normal ly resu l t s in ef fect ive b i te

opening , p rov ided the second molars are included . I f b i te

opening i s no t ach ieved using f la t rectangular s teel wires , then

bi te-opening curves can be p laced . This can be done as la te as

the f in ish ing s tage of t reatm ent , bu t i t i s norm al ly c om ple ted

ear l ier . Toward the end of t reatment in deep-b i te cases ,

p a t i en t s may h av e o n l y 1 -2 m m o f o v erb i t e . Ho wev er , t h ey

wi l l general ly set t le in to a posi t ion wi th approximately

3- 4 m m o f overb i te . Bi te-p late retaine rs are mos t benef icial in

t h ese cases t o p rev en t su b se q u en t o v e rc l o su re o f t h e b i t e .

Open-b i le cases p resen t a g reat chal lenge to the

o r t h o d o n t i s t . It is i mp o r t an t l o ev a l u a t e t o n g u e p o s i t i o n an d

tongue hab i t s in the f in ish ing s tages o f t reatment . I lopefu l ly ,

th is p rob lem was observed pr io r to th is s tage, and

my ofunc l ional thera py in i t ia ted if the hab i t was no t co rrected .

These cases wi l l o f ten benef i t f rom the use o f posi t ioners to

help b i te c losure. I f a convent ional upper retainer i s to be

used , a smal l ho le can be p laced in the palatal surface of the

acry l ic , fo r tongue posi t ion ing . In th is way , some pat ien ts

learn to modify thei r tongue posi t ion or act iv i ty , by ho ld ing

the t ip o f the tongue in the roof o f the palate dur ing

swal l o wi n g an d o t h e r ac t i v i t i e s .

  1

 Iowever , in som e cases , a

tongue wi l l reasser t  itself,  desp i te the best ef for t s o f the

p a t i en t an d t h e o r t h o d o n t i s t . T h e p a t i en t sh o u l d b e i n fo rmed

of th is possib i l i ty before t reatment .

- - - = = = - - a ; = ? = ;= ;

TRANSVERSE CONSIDERATIONS

A r c h f o r m

If a single arch form is used for every patient, i t will give

eff ic iency in arch form m an ag em en t . Howe ver , accuracy and

s t ab i l i t y can n o t b e ach i ev ed i n t h i s man n er . T h e k ey t o g o o d

arch fo rm ma n ag em en t i s t o h av e a b a l an ce b e t we en

eff ic iency an d accuracy . The arch form system descr ib ed in

Ch ap t e r 4 co n s i s t s o f t h e fo l l o wi n g e l emen t s :

• T h ree s t an d a rd t emp l a t es ( sq u are , t ap e red an d o v o i d ) t o

estab l i sh arch form throughout the round wire s tage and

rectan gular he at -act ivated s tage. This i s an ef f ic ien t w ay of

man ag i n g t h e ea r l y s t ag es o f t r ea t men t .

• Use o f a wax t emp l a t e co m p ressed o v er (h e b rack e t s in t h e

lower arch , before p lacement o f the s teel rectangular wire .

The sha pe of the rectangula r s teel wire i s then base d on the

wax temp late . It i s eva luated a nd ad justed af ter reference to

t h e p a t i en t ' s l o wer s t u d y m o d e l . T hi s b ec o m es t h e p a t i en t ' s

i n d i v i d u a l a r ch fo rm ( IAF ) . T h i s s i mp l e t ech n i q u e p ro v i d es

accuracy in the arch form system.

• Al low ing the case to set t le wi th a l ight wire (as op po se d to

the rectangular s ta in less s teel wire) as the las t t reatment

p ro ced u re . T h i s t ech n i q u e wi l l b e d esc r i b ed a t t h e en d o f

t h e ch ap t e r .

A r c h w i r e c o o r d i n a t i o n

In al l wire s izes , once the lower arch form has been

es t ab l i sh ed , t h e u p p er a r ch wi re n eed s t o b e co o rd i n a t ed t o t h e

lower archw ire. In gene ral , th is is ach ieve d by ad just i ng the

u p p e r a r ch wi re so t h a t it is 3 m m wi d er an t e r i o r l y a n d

poster io r ly th an the lower archwir e. This help s to es tab l i s h the

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correct 3 m m of over jet bo t h an ter io r ly an d poster io r ly .

Becau se o f p o s t e r i o r t o rq u e co n s i d e ra t i o n s ( see b e l o w) , i t may

be benef icial in many cases to widen the upper arch in the

p o s t e r i o r seg me n t s t o ap p ro x i ma t e l y 5 m m . I f t h ese

p ro ced u res a r e fo l l o wed d u r i n g t r ea t men t , t h e re i s n o rmal l y

l i t t l e n eed t o ad j u s t a r ch wi re co o rd i n a t i o n d u r i n g t h e

f in ish ing s tages o f t reatment .

S o me cases may sh o w s l i g h t n a r ro wi n g i n t h e p o s t e r i o r

seg men t s n ea r t h e en d o f t r ea t men t , an d a . 0 4 5 a r ch wi re can

b e co o rd i n a t ed wi t h t h e u p p er a r ch fo rm an d wi d en ed

app roxim ately 6 m m pe r s ide. It can then b e secured to the

u p p e r a rch i n th e h ead g ear t u b es (p . 8 2 ) . T h i s s u p p l em en t a l

or ' jockey wire ' i s benef icial in tak ing care o f minor maxi l lary

narrowing in the f in ish ing s tages o f t reatment .

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Establ ishing posterior torque

Progressive buccal crown torque has been designed into the

appliance system in the lower posterior segments, as

described in Chapter 2 (p. 33), and this has been a significant

improvement. When the rectangular stainless steel wire is

placed in the brackets, the lower posterior segments move to

an upright position, providing a relatively flat curve of Wilson

(Fig. 10.14). This does have a slight widening tendency in the

lower arch. However, if arch form is maintained relative to

the basal bone of the mandible, this effect is minimal.

Typically, the lower posterior roots move lingually, away from

the cortical plate, rather than the crowns moving buccally.

The upper cuspid and bicuspid brackets have

  -1"

  of buccal

root torque, and this positions them ideally relative to the

lower arch. Upper molars have been provided with additional

buccal root torque, relative to the research findings, which

helps to place them into the proper position. However, there

are many cases where additional buccal root torque needs to

be added to the posterior segments of the upper archwire.

Due to the anatomy of the upper molar roots, i t is important

to have adequate width in the maxillary bone, so that the

buccal roots are not compressed against the cortical plate (Fig.

10.15). If this occurs, it may be impossible to establish correct

buccal root torque in the upper posterior segments.

Finally, the placement of the upper .045 'jockey wire' in

(he headgear tube (p. 82) is beneficial in many cases.

Following the wide ning effect of this wire, it can be removed ,

and additional buccal root torque can be placed in the

rectangular stainless steel wire. This allows th e poster ior teeth

to move into their proper positions. Then, in the final stage of

settling of teeth at the end of finishing, the upper posterior

segments norm ally settle properly with the lower p osterior

segments.

F i g .  10 .14 D ur ing c o r rec t ion o f t o rq ue , l ow er pos te r i o r r oo ts

m ov e l i ngua l l y aw ay f r om the c o r t i c a l p la te , and the c row ns

move s l ight ly buccal ly , i f arch form is ma inta ine d re la t ive to the

basal bone of the mandib le .

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-9

-14°

F i g .  10.15 I t is im po r ta nt to have ade qua te max i l lary bone for cor rec t buccal roo t to rqu e in the u pper mo lar reg ions .

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DYNAMIC CONSIDERATIONS

Establ ishing centr ic relat ion and checking

Transverse overcorrect ion fun ct ion al mo vem ents

Cases that show narrowing in the maxilla should be

adequately overexpanded and held in the expanded position

for an extend ed period of time . The m axilla can be expa nded

until the palatal cusps of the upper arch are in contact with

the buccal cusps of the lower arch in the posterior segme nts

(Fig. 10.16A). It is best to ex pand cases

  1

 or 2 years prior to

full orthodontic treatment, and to maintain this expansion

with a palatal bar. Then stability is normally assured.

If expansion is carried out at the beg inning of orth odo ntic

treatment, a palatal bar should be placed after the expansion

procedures. This palatal bar can remain in position until (he

rectangular stainless steel wire has been placed. This wire

provides adequate stiffness to maintain the expansion that

has been achieved. Torque in the posterior brackets of the

upper arch, as well as some additional buccal root torque in

the archwire, is beneficial at this time, to allow the posterior

segments to settle properly.

It is impo rtant to evaluate orth odo ntic cases in centric

relation at the beginning of treatment. If not, major

diagnostic errors can be made. This position needs to be

mon itored throu gho ut treatmen t and it is essential to re-

evaluate mandibular position as the finishing stage of

treatment commences (Fig. 10.I6B). It may be that additional

correction is needed, for example with inter-maxillary elastics,

prior to finishing of the case. Patients with occlusion in a

Class I position and with the condyles in centric relation, can

then be checked for interference during protrusive and lateral

excursions. During protrusive movement,  it  is important that

the lower eight most anterior teeth make contact with the

upper six most anterior teeth, with no posterior contact.

During lateral excursions, the patient should experience

cuspid rise with slight anterior contact and disclusion of the

posterior teeth on both the working and the balancing sides.

2

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F i g .  1 0 .16 A C ases w h ic h s how na r row ing i n t he m ax i l l a c an be

ex panded us ing rap id pa la ta l ex pans ion i n t he m ix ed den t i t i on .

Th is ex pans ion c an be m a in ta ined w i t h a pa la ta l ba r , and i t

ass is ts in achiev ing adequate buccal root torque in the upper

pos te r i o r s egm ents .

F i g .  10 .1 6B M o un ted m ode ls m ay be us ed to r e -ev a lua te

m and ibu la r pos i t i on and c hec k func t i ona l m ov em ents as t he

f i n i s h ing s tage c om m enc es .

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.■

Check ing for temporomandibular jo int

dysfunct ion

I t i s i mp o r t an t t o d o cu men t an y ev i d en ce o f

t emp o ro man d i b u l a r j o i n t (T M J) d y s fu n c t i o n p r i o r t o

t reatment , and in form the pat ien t that the condi t ion ex is t s .

Asy mpto ma t ic c l ick ing i s genera l ly no t t reated pr io r to

o r t h o d o n t i c s , b u t mo n i t o red as t r ea t men t p ro ceed s . I f

mu scu l a r i mb a l an ces an d / o r p a i n ex i s t , an d cen t r i c r e l a t i o n

cannot be accurately record ed , then a pha se of sp l in t the rapy

and physical therapy i s ind icated pr io r to o r t hod ont ics . Af ter

t h e p a t i en t h as b een s t ab i l i zed , o r t h o d o n t i c t r ea t men t can b e

c o m m e n c e d .

P a t i en t s sh o u l d a l so b e mo n i t o red d u r i n g o r t h o d o n t i c

t r ea t men t , i n case TM J sy m p t o m s d ev e l o p . If t h ese s y m p t o m s

are managed when they f i rs t occur , p r io r to the fo rmat ion of

t ru e i n t e rn a l d e ran g emen t , t h en f r eq u en t l y n o rmal T M J

fu n c t i o n can b e r e - es t ab l i sh ed wi t h o u t p e rman en t d amag e . I f

symptoms do develop , i t i s f i rs t benef icial to e l iminate the use

of a l l fo rces , such as headgear and elas t ics , whi le reso lv ing the

TMJ pro b le m. Th e pat ie n t i s asked to rem ain o n a sof t d iet ,

an d u se co n se rv a t i v e mea su res t o ma n ag e t h e sy mp t o m s .

If sym pto ms pers is t , then sp l in t thera py and physical

t h e rap y can b e i n i t i a t ed an d o r t h o d o n t i c t r ea t men t d e l ay ed

for a sh o r t p e r i o d . Or t h o d o n t i c t r ea t men t can th en r esu m e

and proceed in a normal fash ion wi th most pat ien ts . I t i s

general ly accep ted that a seated an d rea sona bly c en tered

condyle posi t ion i s the mo st benef icial posi t io n to es tab l i s h

d u r i n g o r t h o d o n t i c t r ea t men t . Co n d y l e p o s i t i o n can b e

ev a l u a t ed c l i n i ca l l y wi t h man d i b u l a r -p o s i t i o n i n g t ech n i q u es ,

an d r ad i o g rap h i ca l l y wi t h co r r ec t ed t o mo g rap h y . Wh i l e so me

cl in icians feel that such rad iographs are importan t in a l l cases ,

t h e au t h o r s d o n o t ro u t i n e l y t ak e t o mo g rap h s u n l es s

s y m p t o m s a r e d e l e c t e d .

In mo s t cases , mi n o r ch an g es can b e mad e d u r i n g t h e

f in ish ing s tage of t rea tm ent to a l low for corre ct ion of con dyl e

an d m an d i b u l a r p o s i t i o n s . F o r ex am p l e , if t h e p a t i en t sh o ws

an an t e r i o r ski d wi t h a co r r e sp o n d i n g an t e r i o r co n d y l e

posi t ion , i t i s benef icial to con t inue wi th headgear o r Class I I

me ch an i cs fo r an ad d i t i o n a l p e r i o d o f l i me t o e l i m i n a t e t h e

an te r io r sk id and al low th e condyle s to seat in the fossae

(Fig . 10 .17) .

Co n v er se l y , i f t h e p a t i e n t sh o w s a s i g n i fi can t ly p o s t e r i o r

co n d y l a r p o s i t i o n wi t h n o ev i d en ce o f an an t e r i o r sk i d , i t i s

benef icial to p rov ide a s l igh t amount o f an ter io r sk id so that

t h e co n d y l e can b e i n a mo re cen t e r ed p o s i t i o n . T h i s may b e

ach iev ed by cea sing Class II e las t ics o r headge ar , o r by the use

of Class I I I e las t ics , and i s par t icu lar ly importan t in cases that

s h o w a C l a s s 111  growth tendency ' (F ig . 10 .18) .

F inal ly , i f the condyles are in a seated and reasonably

cen te red po si t io n , wi th the den t i t ion in a set t led Class 1

p o s i t i o n , ap p l i a n ce s can b e r emo v ed . T h i s sh o u l d a l l o w

n o rm al T M J d ev e l o p m en t an d fu n c t io n a f te r o r t h o d o n t i c

t r ea t m en t . P a t i en t s sh o u l d b e mo n i t o re d d u r i n g t h e r e t en t i o n

p h as e o f t r ea t m en t t o d e t e rm i n e i f T M J sy m p t o m s o ccu r .

Or t h o d o n t i s t s can n o t p r ed i c t t h e p h y s i ca l an d emo t i o n a l

s t ress levels thai wi l l occur wi th thei r pat ien ts , bu t they can

p ro v i d e t h e mo s t sa t i s f ac t o ry s t ru c t u ra l en v i ro n men t t o b es t

wi thst an d these s t ressfu l fo rces .

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F i g .  10 .17 If t he pa t i en t s how s an an te r i o r  sk id ,  w i t h a

cor responding anter ior condy le pos i t ion, i t is benef ic ia l to

cont inue w i th headgear or C lass I I mechanics to a l low the

condyles to seat in the fossae.

F i g .  1 0 .18 I f t he pa t i e n t s how s a s ign i f i c an t l y po s te r i o r

c ondy la r pos i t i on , f u r t he r t r ea tm en t s hou ld be p rov ided , t o

ac h iev e a m ore c en te red pos i t i on .

292

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CEPHALOMETRIC AND ESTHETIC

CONSIDERATIONS

It is often helpful to take progress headfilms approximately

halfway through orthodontic treatment to determine how the

skeletal, dental, and soft tissue components are being

managed. Progress headfilms allow for reassessment of

anchorage factors and help revisions in treatment planning as

treatment proceeds. For some patients, it is necessary to take a

final cephalomelric radiograph. These should be taken

approximately 3 to 4 months before debanding, rather than

after treatment. Taking headfilms after completion of

treatment is useful from a learning standpoint for future cases,

as well as to evaluate the success or failure of the treatment,

but it provides n o specific a dvantage for the patient. It is

better to lake the headfilm before the a ppliances are removed,

so that tooth positions can be corrected if necessary, relative

to PIP and other treatment goals for the case (p. 166).

The most important factors to be evaluated with these

progress and final cephalometric radiographs involve the soft

tissue profile, the antero -posterior position of the incisors, the

torque of the incisors, the changes in the mandibular plane of

the patient, the degree to which vertical development of the

patient has occurred or been restricted, and the success in

correcting the horizontal, skeletal, and dental components of

the problem. Evaluation involves superimposition of progress

and final radiographs with the initial cephalometric

radiograph, to accurately determine the changes that occurred.

TVL

If treatment planning has been based on the Arnett

3

analysis (p. 163), facial profile and the five dentoskeletal

structures can be evaluated in the closing stages of tre atme nt,

before appliances are removed (Fig. 10.19). The Arnett

dentoskeletal ideals are:

• MxOP

• Mx1 to MxO P

• Md1 to MdOP

• over je t

• ove rb i te

f e m a l e

95.6

  ± 1.8

56.8

  ± 2.5

64.3 ± 3.2

3.2 ± 0.4

3.2 ± 0.7

m a l e

95. 0 ± 1.4

57.8 ± 3.0

64.0 ± 4.0

3.2 ±0.6

3.2 ±0.7

I 3.2

64   Ji

I

n

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rCW

a

95

TV L

F i g .

  1 0 . 1 9

  Dur ing the f ina l stages o f t rea tm en t the Arne t t ana lys is may be used to eva luate fac ia l p ro f i le and de ntosk e le ta l

s t ruc tures . The or th odo nt is t can norm al ly p roduc e favorab le change in inc isor to rqu e and over je t /ov erb i te , i f requ i red , bu t may be

less ab le to in f luence the pos i t io n o f th e ma x i l la ry occ lusa l p lane, re la t ive to t ru e ver t ica l l ine (TVL) .

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THE FINAL STAGE OF FINISHING

SETTLING THE CASE

Rectangular s ta inless s tee l working wires a re required for

overbi te control , A/P correc t ion, and space c losure , but they

are somewhat res t r ic t ive for se t t l ing of the tee th in the c los ing

s tages of the t rea tment . Much l ighter wires a re therefore used.

Typica l ly , a .014 or .016 round  I  IANT wi re is used in t he

lower a rch, coo rdin a ted to the IAF for the pa t ien t . In the

upper a rch, a .014 round sec t ional wire can be placed from

lateral incisor to lateral incisor. These wires can be

accompanied by the use of vert ica l t r iangular e las t ics where

se t t l ing needs to occur . The be l te r the bracket p lacement , the

less elastics need to be used in this way. It is beneficial to

ke e p a l l ba nds a nd b ra c ke t s on the t e e th du r ing s e t t l i ng , s o

tha t i f unwanted changes occur , these can be correc ted.

M a na g ing the c a s e in th i s ma nne r a l lows t e e th to

ind iv idua l ly s e t t l e i n to the i r f ina l pos i t ions be fo re a pp l i a nc e

re mova l . Pa t i e n t s c a n be s e e n a t a pp rox ima te ly 2 -we e k

interva ls during the se t t l ing phase . Elas t ics can be worn ful l

time for the first 2 weeks, then at night for a period of 2

we e ks , if s e t t l i ng is a de q ua te . De ba n d in g c a n the n be

s c he du le d .

F i g .

  1 0 .2 0

  L igh t ver t ica l t r ian gu la r e last ics can be used wh ere s e t t l ing needs to occur . Fewer e last ics o f th is type w i l l be requ ired i f

b racket p lacement has been accura te .

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Some varia t ions to th is genera l se t t l ing technique are as

fol lows:

• I f cuspid s were labia l ly d isplaced in the uppe r a rch, th e

sec t ional wire in the upper anter ior segment can be

e x te nde d to the c us p ids to ho ld the m in pos i t ion .

• I f d ias tem as were present in the up per and lower ante r ior

segments , these areas should be t ied together l ight ly with

e las t ic thread or l iga ture wires (Fig . 10.21) .

• If teeth have be en extracted, figure-8 ligatu re wire s sh ou ld

be placed across the extrac t ion s i tes to hold them c losed.

•  If  pala ta l expa ns io n was carr ied out , a sma l l rem ova ble

pala ta l p la te , wi th .018 wires extending in ter-proximal ly in

the gingiva l a reas , can be used to mainta in expans ion

during the se t t l ing phase (Fig . 10.22) .

• W hen finishing m od er ate to severe Class 11/1

malocclus ions , i t i s not wise to use a smal l sec t ional wire

fo r the uppe r a n te r io r s e gme n t , be c a us e s ome re tu rn o f the

overje t can be expected. In th is s i tua t ion, a fu l l upper .014

archwire can be used in se t t l ing (Case DO, p . 210) and th is

wire can be bent back behind the mos t d is ta l molars . This

controls the overje t , but inhibi ts se t t l ing of the pos ter ior

t e e th s ome wha t . Arc hwi re be nds ma y the re fo re be p l a c e d

where individual tee th need to se t t le .

• I f i t i s in te nde d tha t se t t l ing may lake longer tha n

approximate ly 6 weeks , i t i s benefic ia l to leave the lower

re c ta ngu la r s t e e l w i re in pos i t ion du r ing th i s e x te nde d

se t t l ing phase . This wi l l he l p to ma int a in lower a rch fo rm.

An example of th is might be a d i ff icul t pos ter ior open bi te

tha t wi l l require a more extended period of t ime for

se t t l ing. When i t i s ant ic ipa ted tha t only 4 to 6 weeks of

F i g .  10 .21 Du r ing set t l in g i t is necessary to l igh t ly t ie inc isors

toge the r i f a d ias tem a w as p res en t a t t he s ta r t o f t r ea tm en t .

F i g .  10 .22 A rem ov ab le pa la ta l p la te c an be us ed du r in g

s e t t l i ng t o m a in ta in upper a r c h ex pans ion .

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t rea tme nt is rem ainin g, a nor ma l lower .014 stee l or .0 16

heat-ac t iva ted wire can be placed.

Occas ional ly , se t t l ing does not proceed as expected and i t

may be necessary to re turn to the rec tangular s ta inless s tee l

wires . On occas ion, i t may be necessary to repos i t ion some

brackets to a l low the arches to re - leve l and se t t le properly .

This ,

  of course , should have been accomplished a t an ear l ie r

s tage of t rea tm ent , b ut occas io nal ly i t i s necessary . Once the

orth odo nt is t i s sa t isf ied th a t tee th have se t t led in to a

sa t is fac tory pos i t ion, re ta iner impress ions can be taken and

the pa t i e n t s c he du le d fo r de ba nd ing p roc e dure s .

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29

w w w . a l l i s l am. ne t

FINISHING TO ABO REQUIREMENTS

X

o

n

>

In (u ly 2000 , t he Ame r ic a n B oa rd o f Or thodon t i c s (AB O)

cam e ou t wi th revised requir em ents and a grad ing sys tem for

de n ta l c a s t s a nd pa nora mic ra d iog ra phs . '

1

  It i s the authors '

hope tha t th is book wil l be he lpful to readers want ing to

reach ABO goals .

The ABO places emphas is on se l f assessment of seven

features of denial casts . Interestingly, these seven criteria for

cast eva l ua t io n qui te c lose ly matc h (he f in ishing goals

de s c r ibe d in th i s c ha p te r , a nd th roug hou t the book . P rog re s s

models , taken in the f in ishing s tages of t rea tment , and before

a pp l i a nc e re mova l , s hou ld be c he c ke d fo r AB O re qu i re me n t s

for any case which is in tended for presenta t ion. More

specif ica l ly , these inc lude:

• T o o t h a l i g n m e n t . A l m o s t 8 0 % o f m a l a l i g n m e n t s w e r e

found to oc c u r a m on g la t e ra l i nc is o rs a nd s e c on d mo la r s .

C a re w i th b ra c ke t pos i t ion ing (pp 6 1 , 66 , a nd 67 ) c a n he lp

to e l imina te s uc h e r ro r s .

• Marg ina l r idges . Accuracy in vert ica l re la t io nsh ip of the

ma rgina l r idges is im pro ved by us ing gauges and bracket

pos i t ion ing c ha r t s (pp 62 -65) , t a k ing e x t ra c a re in f i r s t a nd

s e c ond m ola r r e g ions , wh ic h a re the mos t f re que n t

p rob le m a re a s .

• B uc c o l ingua l inc l ina t ion . The to rque fe atu re s in the

re c o mm e nd e d b ra c ke t s ys t e m (p . 33 a nd F ig . 4 .40 , p . 89 )

are spec if ica l ly in ten ded to de l iver correc t b uccol ingua l

inc l ina t ion in the mo la r r e g ions .

• Oc c lus a l r e l a t ions h ip . Th e A /P re l a t ion s h ip o f mo la r s ,

pre mo lars and ca nin es is assessed us ing Angle 's

c l a s s i f i c a t ion . C oord ina t ion o f t i p , t o rque , a nd too th s i z e

(with correc t ion where necessary) is required (p . 282) , to

a c h ie ve C la ss I oc c lus ion , a n d th i s i s a t he m e run n in g

t h r o u g h o u t t h e b o o k .

• Oc c lus a l c on ta c t s . Goo d pos te r io r oc c lus ion c a n no rma l ly

be achieved with the he lp of vert ica l e las t ics (p . 294) .

Add i t iona l ly , we l l -c ons t ruc te d pos i t ione rs c a n he lp to s e t t l e

c a s es in t e nd e d fo r AB O pre s e n ta t ion . A c o m m on p rob le m

a re a wa s re po r t e d to be uppe r a nd lowe r s e c ond mola r s . '

1

• Overje t . M eth od s of overje t correc t ion are reviewed in

Chapters 7 and 8 . At tent ion a lso needs to be given to t ip ,

to rque , a nd too th s i z e (p . 282) .

• In t e rp rox im a l c on ta c t s . Te c hn ique s fo r c lo s ing s pa c e s

(p .  25 4) , an d for kee pin g the m c losed du rin g f in ishing

(p .  286) , ha ve be e n de s c r ibe d . Pa r t i c u la r c a re i s ne e de d in

a du l t e x t ra c t ion c a s e s (p . 268) .

f ina l ly , c onc e rn ing roo t a ngu la t ion a s e s s me n t u s ing

pa nora l r a d iog ra phs , i t ha s be e n a c ons i s t e n t f ind ing w i th the

M B T™ s ys te m, tha t roo t a ngu la t ions ma tc h the AB O

re qu i re me n t s , e s pe c ia l ly c onc e rn ing c a n ine roo t s .

REFERENCES

1 B enne t t J, Mc L augh l i n R P 1997 Or t h odo n t i c m anag em en t o f t h e

de n t i t i on w i t h t he p read jus t e d app l i anc e . Is is Med i c a l Med ia , O x f o rd

( ISBN 1 899066 91 8) pp . 50 5 1. Rep ubl ishe d in 2002 by M osby .

Edin bur gh ( ISBN 07234 32651)

2 B e n n e t t J , M c L a u g h l i n R P 1 9 97 O r t h o d o n t i c m a n a g e m e n t o f t h e

3 Ar ne t t G W , Ja l ic J S, K im J et a l 1999 Sof t t issue cep halo me t r ic

ana l y s is : d i agnos i s and t re a t m en t p l ann ing o f den t o f ac ia l de f o rmi t y .

A m e r i c a n J o u r n a l o f O r t h o d o n t i c s a n d D e n t o f a c i a l O r t h o p e d i c s

116 : 239 -253

4 Th e Amer i c an Boa rd o f Or t ho don t i c s C a l i b ra t i on K i t . J u l y , 2000

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de n t i t i on w i t h t he p read jus t ed app l i anc e . Is is Med i c a l Med ia , Ox f o rd

( ISBN 1 899066 91 8) pp. 200 -205 . Republ ished in 2002 by M osby ,

Edinburgh ( ISBN 07234 32651)

296

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CASE MB

A female n on-extra ction case , aged 12.11 years, with a high-

angle pattern (MM   3 7 ° ) .

Molar re la t ion ship wa s 4 m m Class II on the r ight and 2 mm

Class II on the le f t . Al l the tee th were developing normal ly ,

except the upper le f t th i rd molar . Arch form was assessed as

ovo id . I t was dec ided to ma nag e the case on a n on-e xtrac t ion

ba s i s , w i th uppe r a n te r io r to rque a nd lowe r inc i s o r e na me l

re duc t ion .

Fig . 10.23

Fig. 10 .26

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2 9 8

Stan dard meta l brackets were used with .01 6 HANT wires to

c omme nc e too th a l ignme n t . The pa t i e n t wa s a s ke d to we a r a

c ombina t ion he a dge a r du r ing e ve n ings a nd n igh t s . Lowe r

e na m e l re duc t ion wa s de la ye d un t i l c o r re c t upp e r a nd lowe r

inc i s o r to rque ha d be e n a c h ie ve d , wh ic h wou ld re ve a l t he

a m ou n t o f r e duc t ion ne c e ss a ry .

F i g .

  10 .29

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M.B. Beginning

12.1 1  years

8/22796

SN A  / -  75

S N B /

A N B Z

A N

  L FH

Po-N J _ FH

WITS

7 1

4

■ 5

1 6

0

G o G n S N  50

F M / 3 9

M M / 3 7

X to A-Po

1 to A-Po

to

 Max

 P l a n e /

7

3

9 8

m m

m m

m m

m m

m m

t o M a n d P l a n e /  84 °

F i g .  10.24

F i g .

  10.27

on

X

o

-\

JZ

m

n

>

on

F i g .

  10.30

F i g .  10.31

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F i g .

  10.33

F i g .

  10.34

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After 3 months of treatment, upper and lower rectangular

HANT wires are in place.

After 6 months of treatment, .steel .019/.025 rectangular wires

were placed. The patient was asked to wear a right side Class

II elastic (lOOgm ) to comm ence correction of the right side

occlusion and the midlines. Archwires were placed flat,

without additional torque.

Fig. 10.35

Subsequently, after 9 months of treatment, additional torque

was added to the upper wire (Figs 10.41 to

  10.43,

  and 10.46).

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Fig.  10.41

300

It became clear that lower enamel reduction was needed.

Separation and then enamel reduction (Fig. 10.46) of lower

incisors was carried out after 10 m ont hs of treatment, and

first molar bands and upper canine brackets were

repositioned.

Upper and lower rectangular

  1

 IANT wires were used for 1

month lo re-level and align after enamel reduction and

bracket repositioning,

F i g .

  1 0 . 4 4

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Fig.

  1 0 .3 6

Fig. 10.39

F i g .

  1 0 .3 7

F i g .

  1 0 . 4 0

I

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F ig .

  1 0 .4 2

10.45

Fig. 10.43

Fig. 10.46

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m

Normal settling methods were used, with lower bonded and

upper removable retainers.

F i g .

  1 0 .4 7

The case after appliance removal. Active treatment time was

15 months.

F i g .

  1 0 .5 0

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CHAPTER 11

■ B H B H H H H n H B

Appl iance removal

and re ten t ion pro toco ls

Introduction 307

Preparation for appliance removal - the final

adjustment appointment

  308

All-at-one-visit app lianc e remo val 30 8

Progressive app lianc e remov al 308

The appliance removal app ointm ent

  309

Bracket rem oval - meta l brack ets 30 9

Bracket remo val - ceramic brackets 309

Band removal 31 0

Removal of remaining cement and bonding

agents 310

Footprints from bo nd in g agents 31 0

White spots 310

Positioners 31.1

Positioner cons tructio n 311

Bonded retainers 31 2

Lingual bo nd ed retainers 31 2

Palatal bo nd ed retainers 312

Remo vable re ta iners 314

Con venti onal wire and acrylic 314

Vacuum-formed 315

Post-treatment protoc ol 31 6

Post- treatment consu ltat ions 316

Patient letters 31 6

Long-term retention con sider ation s 31 7

Uppe r arch 317

Lower arch 31 7

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INTRODUCTION

W he re ve r pos s ib l e , rou t ine s a nd s t a nda rd a pproa c he s s hou ld

be in t roduced in to or thodont ic prac t ice . This sys temized

a pproa c h c u t s dow n the da y - to -da y de c i s ion -ma k ing a nd

improves eff ic iency. This s ta tement appl ies to a l l aspec ts of

orth odo nt ics , inc l udin g re ten t ion. I t i s essent ia l to have a

good re t e n t ion p ro toc o l .

The authors rout ine ly place a l ingual bonded re ta iner in

the lower a rch for mos t of the ir pa t ients (Fig . 11.1) , a l though

they accept tha t not a l l pa t ients need th is . So me low er labia l

s e gme n t s wou ld re ma in s t ra igh t w i thou t the us e o f a bonde d

re ta iner , but i t i s not poss ible to know which cases be long in

this ca tegoiy .

This approach has the disadvantage tha t some pa t ients wi l l

have re ta iners needless ly , jus t as they may have insurance , but

never use it . However, this policy does at least avoid lower

inc isor c rowding or re lapse during la te adolescence . Such la te

changes are grea t ly disappoint ing to pa t ients , and come a t a

t ime when they are not recept ive to fur ther t rea tment (Fig .

11 .2) .

  La te c ha ng e s a re a l so qu i t e de m a n d in g on p ra c t i ce

resources and u nd er m in e effic iency.

Reitan

1

  s howe d tha t t he pe r iodon ta l l i ga me n t ne e ds a t

leas t 232 days to re -organize af te r tooth movement , and the

elastic supra-c restal fibers n eed 1 year. Ther e is a clear need to

re ta in the resul t aga ins t the or thodont ic re lapse tendency, and

agains t changes caused by la te unfavorable growth. Retent ion

protocol  is a n ind iv idua l c ho ic e fo r ea c h o r thodo n t i s t , a nd

there wil l be differing views conc ern ing h ow r ig id i t sh ou ld

be .

  But a pol icy should be crea ted and adhered to .

F i g .  1 1 . 1

  A . 015 bond ed s p i ra l w i r e r e ta in e r i n p lace a f t e r no n-

ex t rac t i on t r ea tm en t . The au tho rs r ou t i ne l y p lac e l i ngua l

bond ed re ta ine rs f o r m os t o f t he i r pa t i en t s .

F i g .  1 1 .2  Th is f i rs t pre mo lar ex t rac t io n case sho we d lo we r

inci s or r e laps e a t age 18 , and requ i r e d f u r t h e r t r e a tm en t t o

rea l i gn t h e l ow er an te r i o r s egm ent . A l i ngua l bo nd ed re ta ine r

w ou ld hav e p rev en ted the re laps e .

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PREPARATION FOR APPLIANCE REMOVAL

- THE FINAL ADJUSTMENT APPOINTMENT

Before making arrangements for appliance removal, it is

necessary lo ensure that treatment has been completed. All

the recommended checks in finishing and detailing (Ch. 10,

p.  279) should be carried out at the final adjustment

appointment .

Spaces can so metimes appear late in the trea tment. Tie

wires or very light elastic chain (p. 286) should be placed at

the final adjustment appointment lo maintain tight tooth

contacts. This will avoid patient disappointment, and ensure

that the long appointment can be used for appliance removal,

as planned. If ligature wires, instead of elastomeric modules,

are used to attach the archwires at this final adjustment visit,

bracket removal may be easier at the next appo intm ent

(p .

 309) .

The patient should be informed and reassured about

procedures at the forthcoming appliance removal

app ointm ent. Because it will be a long procedure, w ith

laboratory time involved, they should be asked to try not to

re-schedule it . The patient sho uld also be asked to arrange to

see the family dentist for a routine check-up, but not until at

least 4 to 6 weeks after removal of the fixed appliance. This

will allow settling and gingival improvement.

It is necessary to take an impression of the lower anterior

teeth at this appointment, lo allow laboratory preparation of

the multistrand wire. If there are deposits on the lingual

aspects of the lower incisors, it is correct to carry out thorough

cleaning and polish ing at this ap poi ntm en t. This gives a mor e

accurate laboratory m odel. Also, at the subsequent appliance

removal appointment, this will reduce the amount of cleaning

needed, and hence the amount of oozing.

In a few cases, for a variety of reasons, the orthodontist

may agree to removal of appliances before completion of

tooth movements. Such cases may have a greater tendency for

relapse, and man y ortho dontists ask the patient to sign a

release statement, acknowledging early app liance removal.

This confirms that the patient has been informed that the

treatment has not been completed, and that further

Al l -at -one-v is i t appl iance removal

It is normally preferable to remove all the orthodontic

appliances at one visit. This is most convenient for the

patient, and efficient in terms of practice scheduling, because

the appliance removal and polishing instruments only have to

be laid out on one occasion. Also, it is normally necessary for

the orthodontist to retain control of both arches until the

completion of tooth movements. Partial debonding can leave

certain teeth unretained and subject to unwanted movement.

This appointm ent shou ld be the high point of the

orthodontic treatment for the patient. Scheduling a long

morning appointment will allow an unhurried approach to

appliance removal. There will be ade quate time for discussion

and instruction concerning retention, and for the orthodontist

and pat ient to enjoy the moment.

Progressive appl iance removal

In some situations, it may be decided to gradually remove the

appliances, over two or more visits. If one arch requires a lot

less treatment than the other, for example, then it may be

logical to consider early appliance removal in that arch. In

some longer treatments, the patient may be glad to be offered

early removal of upper ap pliances, in return for agreeing to a

few more months of lower arch treatment.

Progressive appliance removal is recom men ded for adult

treatments where bands are used, or where teeth were

extracted. The terminal molar bands may be left in place and

elastic chain o r active tiebacks used lo close ba nd spaces

elsewhere.

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improvement could be achieved.

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THE APPLIANCE REMOVAL APPOINTMENT

Bracket removal - metal brackets

A  debracketing instrument (3M Unitek 444-761) or old

ligature cullers are used to remove metal brackets (Fig. 11.3).

When using the debracketing inslrument, if the archwires are

held in place with lie wires, the brack ets can be deta che d from

the toolh surfaces without first taking out (he archwires. The

archwire may then be removed with the brackets attached to

it (Fig. 11.4), avoiding the possibility of loose brackets in the

mouth. When using old ligature cutters, archwires may be

removed with the brackets attached if (ie wires or elastome ric

modules are in place.

Bracket removal - ceramic brackets

Ceramic Clarity™ brackets are removed using a different

technique. Archwires need to be taken out first, and any

excess bon ding agent rem oved from around the brackets,

using a high-speed flame-finishing bur (Fig. 11.5). bach

bracket may then be collapsed by gripping it mesially and

distally using band-seating pliers and squeezing (Fig. 11.6). It

can help the confidence of nervous patients, or those with

slightly mobile teeth, if they use each anterior toolh in turn to

firmly bite on to a cotton roll at the time of bracket removal.

On (he rare occasions when a ceramic bracket does not

fully detach itself from the tooth surface, it is necessary to

remove the remains using high-speed diamond instruments,

copious amounts of water, and high-volume suction.

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cutters can be used to rem ove me tal bracke ts.

F i g .  11 .5  I t is cor rec t to remo ve any excess bo nd ing ag en t

be fo re r em ov ing C la r i t y ™ b rac k e ts .

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Fig .

  11.4

  If the archwire is remo ved w i th t he brackets a t tache d

to i t , this avoids the p ossibi l i ty of loose b rackets in th e m ou th .

F i g .  1 1 . 6  Band-sea t ing p l iers (3M Un i tek 900-711) are used to

col lapse the C lar i ty™ bracket by squeez ing mes io-d is ta l ly , so

that i t c loses l ike a book . The p l iers are appl ied approx imate ly

1 m m aw ay f r om th e too th s u r fac e .

309

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Band removal

Whi te spots

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Band removal p l iers can be used to easi ly remove most molar

b a n d s .

  Lif t ing f rom the d is to -g ing ival aspect i s normal ly

effective. Only rarely is i t necessary to use a high-speed dril l to

cu t t h e b an d mat e r i a l .

Removal o f remain ing cement and

bonding agents

Af t e r d e t ach men t o f a l l t h e b an d s an d b rack e t s , t h e r emai n i n g

cemen t may b e r emo v ed u s i n g sea l e r s o r b an d - r emo v a l p l i e r s ,

an d then h igh-s peed f lame-f in ish ing burs , wi thou t a wate r

sp ray . T ee t h m ay b e p o l i sh ed u s i n g co n v en t i o n a l ru b b er cu p s

an d p u mi ce o r a p ro p r i e t a ry p o l i sh i n g ag en t . I n i n s t an ces

wh ere t h e re i s co n s i d e ra b l e g i ng i v a l en l a rg eme n t a t t h e t i m e

o f ap p l i an ce r emo v a l , p a r t o f t h e r e s i d u a l cemen t an d

bonding agen t may be temporar i ly lef t on the teeth . Af ter a

mo n t h o f g o o d p l aq u e co n t ro l , t h e g i n g i v a l co n d i t i o n wi l l

the n no rm all y allow a clear field for final clean ing an d

p o l i sh i n g .

F i g .  11.7 I t is im po r ta nt to m in im ize the poss ib i l i ty o f

decalc i f icat ion marks on the teeth.

Footpr in ts f rom bonding agents

Deca l c i fi ca ti o n sp o t s o n t h e t ee th can b e mo s t d i sap p o i n t i n g

to or thodont is t , pat ien t , paren ts , and referr ing den t i s t (F ig .

11 .7) . The f inger i s o f ten po in te d tow ards the o r th odo nt is t

co n cern i n g t h e cau se o f t h e p ro b l em. Wh i l e t h i s i s g en era l l y

not the case, i f the pat ien t ' s a t ten t ion to o ral hyg iene ear ly in

t h e t r ea t m en t i s p o o r , i t i s i m p o r t an t t o mi n i m i ze t h i s

p ro b l e m. A su g g es t ed p ro t o co l can b e co n s i d e red an d

explained to the pat ien t , in le t ter fo rm, p re- t reatment .

• At the first visi t that poo r oral hyg iene is not ice d, th e

pat ien t i s in formed of the condi t ion and to ld that i f there

is no improvement by the fo l lowing v is i t , wires wi l l be

r e m o v e d .

• The pat ie n t can then be checked br ief ly at 2 to 3 week

in tervals un t i l ther e i s im pro vem en t , wh ich i s usual ly the

case.

• II no imp rov em en t occurs af ter two to th ree v is i t s wi thout

a r ch wi res , t h e an t e r i o r b r ack e t s can b e r emo v ed u n t i l t h e re

is improvement . Th is i s rarely needed , i f p roper l imi ts are

set .

• I f there i s s t i ll no respo nse, the n rem oval o f the app l iances

o r t r an s fe r t o an o t h e r o r t h o d o n t i s t i s r ec o m m en d ed . T h i s

is rare indeed .

The causes o f local ena me l decalci f icat ion are m ul t i -

factor ial .

3, 4

  Good oral hyg iene i s impor tan t , bu t there i s a l so

i n d i v i d u a l v a r i a t i o n in p l aq u e ty p e an d co mp o s i t i o n . S o me

pat ien ts wi l l have a g reater r i sk o f local changes in eco log ical

balance, lead ing to decalci f icat ion .

I t i s no t p ossib l e to iden t i fy those in d iv idu als wh o are

pred ispo sed to local decalci f icat ion , bu t it i s c lear that a smal l

g roup of pat ien ts i s responsib le fo r a large percen tage of the

affected te eth . For so m e pat ie n ts i t ma y be helpfu l to adv ise

o n e o r t wo week s o f ad d i t i o n a l r i n s i n g wi t h p ro p r i e t a ry 0 .2 %

ch l o rh ex i d en e r i n se , acco rd i n g t o t h e man u fac t u re r ' s

inst ruc t ions . This m ay help to favorab ly cha nge the bacter ia l

f lo ra an d res to re eco log ical ba lance .

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310

Some pat ien ts have a f luoro t ic type of enamel , and they may

sh o w ' en amel fo o t p r i n t s ' a t t h e t i me o f ap p l i an ce r emo v a l . A t

t h e case se t -u p ap p o i n t m en t e t ch an t i s n o rm al l y ap p l i ed o n l y

lo the b racket base area. At the end of t reatment , af ter de-

bonding , there may be res idual res in in the p rev iously etched

area o f en amel , w i t h an ap p earan ce wh i ch co n t r as t s wi t h t h e

f luoro t ic enamel . Th is 'b racket base area ' may have a bet ter

ap p earan ce t h an t h e u n t r ea t ed en amel . F o r t h i s r easo n i t

might be considered log ical to e tch the en t i re lab ial surface

for some pat ien ts wi th f luoro t ic enamel , a l the t ime of case

set -up . This is curren t ly being invest igated .

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B I M U I U U

  l < — — — — — — — — — — — — — — — — — —

POSITIONERS Po sit ione r co ns tru ctio n

A high percentage of cases can b e wel l t rea ted w itho ut the

need for tooth pos i t ioners . However, they can   be useful  in the

fol lowing s i tua t ions :

• Fo r pa t i e n t s wh o ha ve s how n e xc e l le n t c oop e ra t ion and

who want idea l se t t l ing, wi th  the bes t poss ib le resul t . M any

pa t i e n t s be c ome t i r e d towa rds the e nd  of t r e a t m e n t , and

are not able  to coo per a te fu lly  in no rm al finishing  and

de ta i l ing p roc e dure s .

• For pa t ie nts wi th pers is tent ante r ior o r pos te r io r tong ue

ha b i t s . A p rope r ly c ons t ruc te d pos i t ion e r c a n ha ve a b i t e -

closing effect.

•  In so m e t r e a t m e n t s, it is necessary to r e m o v e the

appl iances ear ly , for a varie ty of reaso ns . F urther

i m p r o v e m e n t c a n  be ob ta ine d fo r the s e pa t i e n t s  if  they will

wear

 a

 pos i t ione r , but suff icient coop era t ion is se ld om

for thc oming!

Pos i t ioners can  be used  at  t h e c o m p l e t i o n  of  o r t h o d o n t i c

t re a tme n t to a l l o w for  idea l se t t l ing of the occ lus ion. Major

too th move me n t s s uc h  as to rqu e c on t ro l , s ign i f ic a n t ro t a t ion ,

a nd t ip c on t ro l a re no t pos s ib l e . M inor s e t t l i ng move me n t s ,

inc luding t ipping and rota t ion, can be carr ied out if

coopera t ion  is  re a s ona b le .

The major obs tac le

  to

 the success

 of

 p o s i t i o n e rs

  is

  pat ient

coopera t ion. Pa t ients a re of ten t i red  at  the e nd  of  o r t h o d o n t i c

t rea tment and are not wi l l ing  to p u t  in the a dd i t io na l t ime

and effort  to  we a r a  pos i t ione r .  If it is p l a n n e d  to u s e a

positioner,  it is bes t  to expla in th is to  the pa t i e n t at the

beginning of trea tm ent . Therefore , off ices tha t use p os i t io ners

frequently , genera l ly inform the ir pa t i ents before t r ea tm ent ,

and achieve a bet te r overa l l respon se than thos e tha t sugges t a

pos i t ioner at the very en d  of  t re a tme n t .

T h e t e c h n i q u e  for pos i t ion e r c ons t ru c t ion  is as fol lows:

• Co mp le t e the case as wel l  as pos s ib le th rou gh the s e t t l i ng

stage.

• With brackets on , take two se ts of upp e r a nd lowe r

impre s s ions . One s e t  is used for a  reference,  and the

s e c ond set is us e d  for  pos i t ion e r c on s t ruc t ion .

• Ta ke a  fa ce bow re c o rd ing a n d  a centr ic re la t ion wax bi te ,

fo l lowe d  by m o u n t i n g  of the case o n an  art icula tor . This is

critical  so  tha t the axis of op e n i ng i s c o r re c t a nd the

pos i t ione r ma te r i a l be twe e n the t e e th  is the r ight th ickne ss

both anter ior ly and pos ter ior ly .

• C o n t in ue de ta i l i ng the c a s e as ne e de d w h i l e the po s i t ione r

i s be ing c ons t ruc te d .

• Th e l a bo ra to ry c a n  be ins truc ted  to set all the teet h or to

jus t se t cer ta in tee th tha t need improvement . The normal

pos i t ione r ma te r i a l s c ons i s t  of mode ra te ly s o ft wh i t e

rubber , sof t c lear mater ia l ,  or mater ia l tha t wi l l sof ten

w h e n h e a t e d  and  h a r d e n w h e n b r o u g h t  to  m o u t h

t e m p e r a t u r e .

• W h e n  the pos i t ione r a r r ive s , a l l o r th odo n t i c a pp l i a n c e s c a n

be re move d

  and

  the pos i t ione r p l a c e d . The re a re ge ne ra l ly

two op t ions c onc e rn ing pos i t ione r we a r :

— we a r ing the a pp l i a nc e  as m u c h  as pos s ib le for 2  weeks ,

fol lowed  by nigh t w ear for a  m o n t h a n d t h e n p l a c e m e n t

of re ta iners

— us ing the pos i t ione r a s a re ta ine r for a  mo re e x te nd e d

p e r i o d  of l ime .

Pos i t ioners a re mos t e ffec t ive with pa t ients who presented

w i t h  an ope n -b i l e t e nde nc y . Th i s  is be c a us e p os i t ione rs in

ge ne ra l ha ve a  bile -clo sing effect. They also h elp  to  prevent

the tong ue from c a us ing too t h mo ve m e n t wh e n the y a re

worn. Converse ly , cases tha t begin in i t ia l ly wi th  a  de e p b i t e

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are not bes t sui ted for a  pos i t ione r ; no rm a l re t e n t ion is

p r o b a b l y  a  be t t e r op t ion .

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BONDED RETAINERS

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L ingua l bonded re ta ine rs

The a u tho rs p rov ide a lowe r c a n ine - to -c a n ine l ingua l bonde d

re ta iner for a lmos t a l l pa t ien ts a t the end o f t rea tm ent . In f i rst

premolar extrac t ion cases , th is is normal ly extended on to the

mes ia l fossae of the secon d prem olar s . Th e mu ll is i ra nd wire

may be .01 5 or .01 95, and i t is bo nd ed us ing Tr an sbo nd LR™,

with a met icu lous tech niqu e . The wire can be mad e a t the

chairs ide , but grea ter accuracy and adapta t ion are poss ible i f i t

i s made on a model in the labora tory .

Careful cleaning of the lingual surfaces of the teeth is

needed - much more than on the labia l surface . A met iculous

te c hn iq ue ne e ds to be fo llowe d wh e n bon d in g l ingua l o r

palatal retainers, ensuring a perfectly dry field. As an

al te rna t ive to convent ional isola t ion with cot ton rol ls , the

fo l lowing t e c hn iq ue c a n be c ons ide re d . A rubbe r da m c a n b e

placed to isola te the a rea . Orthodont is ts or the ir ass is tants may

be res is tant to the use of a rubber dam, because of the smal l

a m ou n t o f a dd i t iona l l ime re qu i re d . Howe ve r , w i th s o me

e xpe r i e nc e , t he p roc e d ure goe s s moo th l y a nd qu ic k ly , w i th l e ss

po te n t i a l fo r mo i s tu re c on ta mina t ion . M ic ro -e t c h ing c a n be

used a t low pressure and for a short t ime for in i t ia l c leaning.

This can not b e cons idered as a sub s t i tu t e for ac id e t ching ,

2

whic h s ho u ld b e c a r ri e d ou t i n the no rm a l wa y wi th 37 %

pho s pho r i c a c id fo r 20 to 30 s e c onds . Th orou gh r in s ing a nd

drying are then essent ia l . Care is taken not lo move the wire

dur in g bond in g , a nd a de q ua te l i gh t is u s e d . Few b re a ka ge s

occur .

Pa la ta l bo nd ed re ta ine rs

These are not used as frequent ly as lower l ingual re ta iners ,

because of the potent ia l for breakage due to occ lusa l contac t ,

or contac t during bi t ing. However, they are essent ia l to ensure

good re t e n t ion o f ma ny a du l t c a s e s , be c a us e s ome pa t i e n t s

experience pers is tent spac ing (espec ia l ly in the midl ine) or

o the r uppe r inc i s o r move me n t s . The a dva n ta ge s o f pa la t a l

bonde d re t e n t ion ou twe igh the po te n t i a l r i s k o f b re a ka ge in

such cases.

Before placement , the pa t ient 's overbi te and overje t should

be evalua ted. Care should be taken to place the wire away

from the area of contac t . A mult is t rand wire of s ize .015 to

.0195 can be used, and placed in a manner s imilar to the

lowe r bon de d re t a ine r (F igs 11 .8 & 11 .9 ) . Th e pa t i e n t s hou ld

be asked to be careful wi th th is wire , in order to avoid

breakages . With proper care , they can remain in p lace for a

long t ime .

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F i g .  1 1 . 8

  The T rans bond LR ™ m ate r ia l m ay be tak en f r om th e

d is pens ing s y r i nge on to a hand i ns t r um en t .

F i g .  1 1 . 9

  A l t e rna t i v e l y , t he bond ing m ate r i a l m ay be app l i ed

d i r ec t l y f r om th e s y r i nge , and th i s is no rm a l l y t he p re fe r red

m e t h o d .

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M M H B H

Lab ia l bo nd ed re ta iners

Bonded labial retainers for upper incisors are increasingly

being considered. This may be useful as a short-term mea sure

for impatient adults, allowing earlier removal of brackets.

After a few m onth s with a labial b ond ed retainer, m ore

conventional methods can be used for retention. In

adolescent treatment, labial bonded retainers can be useful in

a 'pause' phase, while awaiting eruption of m ore teeth

(Fig. 11.10).

Fig.  11 .10A and B

  Th is C lass I I/2 ma locc lus ion was t re a t ed to ach ieve in i t ia l a l i gn me nt over a 9 mo nt h pe r iod .

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F i g .

  1 1 .1 0 C a n d D

  I t was necessary to pause to a l lo w ex t rac t ion o f low er second pr imary mo lars and eru p t i on o f the low er second

premolars.

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F i g .

  11 .10E and F

  T h e b o n d e d b r a cke t s we r e r e m o ve d , a n d a n u p p e r l a b i a l b o n d e d w i r e w a s p la ce d t o s ta b i l i ze t h e im p r o ve m e n t .

M o la r b a nd s we r e l e f t i n p l a ce . A f t e r a 6 - m o n t h p a u se , a n d f o l l o w in g t h e n e ce ssa ry p r im a r y t o o t h e x t r a c t i o n s a n d e r u p t i o n o f t h e

l o we r seco n d p r e m o la rs , i t wa s p o ss ib l e t o r e su m e t h e t r e a t m e n t . Du r i n g t h e p a u se , t h e r e wa s sp o n t a n e o u s im p r o ve m e n t a m o n g s t

t h e b u cca l o cc l u s i o n , a n d m in im a l p a t i e n t co o p e r a t i o n wa s r e q u i r e d w i t h r e t e n t i o n .

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In other cases, it may be helpful to provide local bonded

labial retention for a few teeth, in addition to vacuum-formed

retainers. For example, this is helpful after correction of

severely rotated teeth or palatally placed canine s (Fig. 11.11),

which have a high probability of relapse, and which are not

well retained using only Hawley or vacuum-formed retainers.

F i g .

  1 1 . 1 1  A f t e r c o r rec t i on o f pa la ta l l y pos i t i oned pe rm ane n t c an ines , i t is he lp fu l t o p lac e a loc a l bon ded l ab ia l r e ta ine r , i n

ad d i t i o n t o c onv e n t i ona l upper r em o v ab le r e te n t i on . Such tee th hav e a s t r ong p ro bab i l i t y o f r e laps e , an d rem ov a b le r e ten t i on is

s e l d o m a d e q u a t e .

REMOVABLE RETAINERS

C o n v e n t i o n a l w i r e a n d a c r y l i c

Wire and acrylic removable retainers can be useful in the

conventional 'wrap-around' or Begg type, for maintaining

space closure after extractions, or as a Hawley type in deep-

bite cases (Figs 11.12A & B) where the upper retainer needs to

carry a bite plane.

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314

F i g .

  11 .1 2A Ac ry li c H aw ley re ta ine rs c an be us e fu l w h en

reta in ing deep b i te cases .

F i g .  1 1 .1 2 B

  H aw ley re ta ine rs c an be c ons t ruc ted w i t h a b i t e

p lane to ass is t in re tent ion of deep-b i te cases .

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Vacuum-formed reta iners

Vacuum-formed retainers have man y advan tages over wire

and acrylic for most patients needing removable retainers.

They are rapid and economical lo make, require no

adjustment, and, if well made, are easy, comfortable, and

esthetic to wear. Due to their greater accuracy, concerns have

been expressed that they may slow the settling process.

I  lowever, many orthodontists report that this is not as great a

problem as might be expected.

F ig .  11.13

  Vac uum - fo rm ed re ta ine rs a re r ap id and ec onom ic a l t o m ak e , and a re c om fo r ta b le and es the ti c t o w ear .

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.

POST-TREATMENT PROTOCOL

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Post- t reatment consul tat ions

Man y ort ho do nt i s ts f ind it he lpful (o hav e a sho rt po s t-

t rea tment consul ta t ion. At th is v is i t , i t i s poss ible to review

the in i t ia l pro ble m an d f inal resul ts . It i s qu i te surpris in g h ow

pa t i e n t s c a n fo rge t t he de ta i l s o f t he i r be g in n ing p ro b le m .

R e f res h ing the i r me mo r ie s l e a ds to ha p p ie r pa t i e n t s a nd mo re

referrals!

Since the ava i labi l i ty of d igi ta l imaging sys tems such as

Dolphin™ Imaging, i t has become re la t ive ly quick and easy to

provide before and af te r p ic tures .

Patient let ters

A few days after removal of fixed appliances, i t is helpful to

send a s tandard le t te r to the pa t ient . This can he lp to . reduce

the s t re s s a nd work loa d fo r the o r thodon t i s t du r ing the

re ten t ion p hase . A seco nd le t te r can be sent 1 year la te r .

The f i r s t l e t t e r e mpha s iz e s the impor t a nc e o f the re t e n t ion

pha s e o f the t r e a tme n t ( re ga rde d by ma ny o r thodon t i s t s a s a

ma jo r c ha l l e nge ) a nd c a n s uppor t t he pos t - t r e a tme n t

consultation. Suggested text for the first letter can be as

fol lows:

Dear

Congratulations on the recent successful completion of the active

phase of your orthodontic treatment Now that the fixed

appliances have been removed, we are ready to begin the

retention phase. The teeth and tissues have not completely

adjusted to their new positions yet, and retainers are necessary

to hold the teeth in their new positions, allowing for settling of

the supporting tissues.

The fees includ ed provision of a set of retainers and their

maintenance over a I-year  period.  If it is necessary to continue

retention supervision beyond that point, appointments will be

charged on a per visit basis. We recomm end thai you see your

general dentist for a thorough dental check-up about 4 to 6

weeks after removal of the fixed appliances.

We look forward to continuing your successful orthodon tic

After 1 year of re te nt io n, a sec ond s tan dar d le t te r can be

sent . Both le t te rs remind the pa t ient tha t the quoted fee

covered on ly the ac tive ph ase of t rea t me nt an d 1 year of

re tent ion. Text for a second le t te r can be as fo l lows:

Dear

I am pleased to confirm that your supervised retention program

has now concluded, and you no longer need to see us on a

regular basis. You should continu e to wear your retainers, as

advised, in order to maintain the best results; conscientious,

long-term wear should ensure lasting stability of the

improvement.

Ij you wish to make future appointm ents, either for a general

orthodon tic chec k-up, or if you have any difficulties with your

retainers, w e will be glad to help. A c harge will be made for

such visits. Please do not hesitate to contact us should you

require advice or support in any way.

I'd   like to take this opportunity' to stress the ongoing need for

your regular reviews with your general dentist in order to

maximize the result we have achieved.

Yours sincerely

Two ve rs ions o f the s e l e t t e r s a re ne c e s s a ry , de pe nd ing on

wh eth er the pa t i ent is a chi ld o r an adu l t . They are kept on

d i s c, o f c ou rs e , a nd a re mod i f i e d o r ma de m ore p e rs ona l a s

necessary .

I t has been reported by Bishop

5

  tha t an Aus tra l ian

phys ic ian, Dr M.H .N, Tat te rsa l , found tha t fo l low-u p le t te rs

grea t ly improved the pa t ient percept ion of the service he had

provided. Tota l ly sa t is f ied ' - the highes t ra t ing - was reported

by 54% of thos e who re c e ive d l e t t e r s , c ompa re d w i th on ly

I  6% wh o d id n o t !

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treatment during the retention   period and to seeing you again

in due

  course

 for your next retainer check. If you have any

questions, please let us know.

Yours sincerely

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LONG-TERM RETENTION

CONSIDERATIONS

The protocol concerning long-term retention varies greatly

among orthodontists. Also,

 the

 level

 of

 cooperat ion a mon g

patients after treatment may  vary even more! Some

orthodontists

67

  believe that  if beg innin g arch form (especially

inter-cuspid w idth)

  is

 preserved, contact points

 are

 flatted

  for

stability,

 and

 fiberotomies

  are

 carried

 out

  where needed, that

little

 or no

 retention

  is

 necessary. Other work

8, 9

  suggests that

if teeth

 are to

 remain

  in

  position, permanent retention

 is

needed. While each of these possible approaches may be

satisfactory  in certain cases, they may not be appropriate for

others. Each orthodontist will establish

 a

  protocol,

 and the

following 'mid dle

 of

  the road' approach might

  be a

  useful

basis

 for

 decision making.

Upper arch

As

 the

 majority

 of

 relapse

 in the

 upper arch occurs within

 the

first

  6

 months ,

 the

 patient

 can be

 requested

  to

 wear

 a

removable retainer full time, or as often  as possible. After this,

the patient

 can

 gradually

 go to

  night-time hours, while being

observant

 of

 pressure areas that

 may

 occur.

 If

  these occur,

longer retention

  may be

 necessary. Eventually,

  the

 patient

may move towards no  upper retention.

Lower arch

The lower anterior segment  has  long been considered the

'foundation  of the house', especially du ring the later stages of

growth

  and

 development .

 The

  lower bonded retainer

 can

therefore

 be

 left

  in

 place until growth

  is

 complete

  in

  young

patients,

 and for

 approximately

 2

 years

 in

 adults. After this,

case-by-case decisions

 can be

 made concerning removal .

REFERENCES

1 Reitan

 K 1959

 T i ss ue rea r ran gem en t du r i ng re t en t i on

  of

o r t h o d o n t i c a l ly r o t a t e d t e e t h . A n g l e O r t h o d o n t i s t 2 9 : 1 0 5 -1 1 3

2  Van W av e ren H ogerv o rs t  W L, Fe i lzer A  J et al  2000 The air  abras ion

t ec hn ique v e rsus the  c o n v e n t i o n a l a c i d - e t c h i n g t e c h n i q u e : a

q u a n t i f i c a t i o n of  sur face enamel loss and a c o m p a r i s o n of  s hea r bo nd

s t reng t h . Amer i c an J ou rna l of  O r t h o d o n t i c s  and  D en t o f ac ia l

Or thopedics 117:20-26

3 Mi tchel l

 L, 1992

 D e c a l c if i c a ti o n d u r i n g o r t h o d o n t i c t r e a t m e n t w i t h

f ixed appl iances

 - an

  ov e rv iew . B r i t i s h J ou rna l

 of

  O r t h o d o n t i c s

19:199-205

4 Tw e t man

 S,

 H a l l g ren

 A,

  Peterson

 LG, 1995

 Ef fec t

 of an

  an t i bac t e r i a l

varn ish on  mu t ans s t rep t oc oc c i  in  p l a q u e f r o m e n a m e l a d j a c en t  to

or thodont ic appl iances . Car ies Research 29:188-91

5 Bishop J

 E 1991

  T e c h n o l o g y

  and

  med i c i ne ; doc t o rs

 get

  results

 by

s end ing l e tt e r s a f t e r t r ea t m en t s . W a l l S t ree t J ou rna l Oc t obe r 11 : 134

6 Boese L R 1980 F i b e r o t o m y  and  r e p r o x i m a t i o n w i t h o u t l o w e r

re t en t i on , n i ne y ea rs

  in

  r e t ros pec t : pa r t

  1.

 A n g l e O r t h o d o n t i s t

50 : 88 -97

7 Boese

 L R 1980

 F i b e r o t o m y

 and

  r e p r o x i m a t i o n w i t h o u t l o w e r

re t en t i on , n i ne y ea rs  in  r e t ros pec t : pa r t  2. A n g l e O r t h o d o n t i s t

50 : 159 -178

8 L i t t l e R M,  Reide l R A,  A r t u n J 1988 An  e v a l u a t i o n of  c hanges  in

m a n d i b u l a r a n t e r i o r a l i g n m e n t f r o m  10 years to 20 years

p o s t r e t e n t i o n . A m e r i c a n J o u r n a l  of  O r t h o d o n t i c s and  D en t o f ac ia l

Or t hoped i c s 93 : 423 -428

9 L i t t l e

 R M,

  W a l l e n

 T R,

 R e ide l

 R A 1981

  S t ab i l i t y

  and

  re lapse

  of

m a n d i b u l a r a n t e r i o r a l i g n m e n t

  -

  f i r s t p rem o la r c ases t r ea t ed

  by

t r a d i t i o n a l e d g e w i s e o r t h o d o n t i c s . A m e r i c a n J o u r n a l

  of

  O r t h o d o n t i c s

80 : 349 -365

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 by UST

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Problem

Index

Acrylic bit e plate s 1 35, 171

Acrylic retainers 83, 314

Adenoids removal 143, 144

Aligning see  Leveling and aligning

Analgesics 112

Anchorage contro l 94

antero-poster ior 100-106

Class II treatment 172, 173

definition 94

lateral (coronal) plane 108

MBT bracket system 15

principles 94

recogniz ing needs 96-97

reduction of needs 99

space c losure 250, 260-262

vertical 106-107

Andrews' bracket system 4-5, 27

Anterior bite plates 134, 135

Anterior open b ite 142 -14 4

development 142

early management 143

elimination of environmenta l fac tors 142

management during fu l l or thodontic

trea tment 144

skeletal cases 142

Anterior tip values 4, 8, 9

MBT bracke t system 9, 15

Antero-poster ior anchora ge supp ort 100 -10 6

bendbacks 102-103

Class 111  elastics 104

headgear 104, 105

lacebacks 100-101

lingual arches 104

palatal  b ar  106

APC brackets 6 9

APo line 168

Arch form 72-84

v

MBT bracket system 12, 16

mo d i f ic a t io n s 8 0 -8 2

after maxillary expansion 80

poster ior torque considera t ions 80

ovoid 12 , 16 , 74 , 75 , 76 , 77 , 78 , 289

practica l aspects 74-76

recommended ra t ios 75

re tention 83

square 12 , 16 , 74 , 75 , 76 , 77 , 78 , 81 , 289

stabil i ty /re lapse fo l lowing trea tment-re la ted

change 72 , 73

standardized wires 77

Straight-Wire Appliance (SWA) 4

tapered 12 , 16 , 74 , 75 , 76 , 77 , 78 , 2 89

templates

c lear  7 7

wax 289

variability 73

Archwire hooks 18

MBT bracket system 18- 19

space closure with light forces 254

turning in ends 112

Arcbwires 13, 14

b en d s 2 8 8 , 2 9 5

closing loop 252

coordination 289

customized 77 , 78 , 84

adaptation to individual arch form (IA1-)

7 8 - 7 9

expansion technique 81

finishing stages 20, 288

(laming and quenching 103, 112

forces

  see

  Force levels

l igat ion methods 20

o p en in g 1 1 2

plastic sleeving 112

removal with brackets 308

selection 3

Articulators 6

Asymmetrical lower arch 82

Bacterial endocarditis 69

Bendbacks 7

antero-poster ior inc isor contro l 102 -10 3

Class II treatment 171

MBT bracket system 8, 15

Bicuspid extractions, anterior open bite 144

Bimaxillary protrusion 97

Bimaxillary retrusion 97

Bite-opening curves 137

Bite-plate effect 1 34 -1 35

creation methods 135

Bonded re ta iners 312-314

lab ia l 3 1 3 -3 1 4

palatal 312

Bonding mater ia ls  57 ,  68, 69

Bracket design 28-30

anchorage needs reduction 99

MBT bracket system 8

see also

 Bracket system versatility

Bracket positioning 3, 280, 281

accuracy 13 , 57 , 59 , 60 , 61 , 69

anter ior open b ite 144

axial 61

b o n d i n g 6 8 - 6 9

horizonta l 60 , 283, 284

McLaughlin and Bennett t rea tment approach

7

MBT bracket system 11, 13

mo la r b an d s p lacemen t 6 6 -6 7

position for viewing teeth 59

re-leveling procedures 109

rotated incisors 61

rota t ion contro l 285

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asymmetries 82

canine bracket selection 45

classification 74

clinical issues 73

control

early treatment 77

rectangular IIANT wires 78

rectangular steel wires 78

customization 72

customized wires 77, 84

finishing 83, 289

'ideal' 72, 73

McLaughlin and Bennett treatment approach

7

MBT bracket system developm ent 12

sequencing 110, 111

se t tl in g p h ase 8 3 , 2 9 4 , 2 9 5

space closure with light forces 254

s tan d a rd ized 7 7

stock contro l 77 , 78 , 84

turning in ends 112

upper arch expansion 81

jockey arch use 82

Arnelt analysis

Class  11  cases 163, 164-165, 168, 169

Class  111 cases 220, 221

dentoskeletal ideals 293

Straight-Wire Appliance (SWA) 4

theoretical aspects 59

vertical 61, 288

bracket-posi t ioning charts 61 , 63-65

use of gauges 61 , 62

Bracket system versatility 13, 39-54

canine torque options 44

in terchangeable brackets

lower incisor 48

upper premolar 49

main areas 39

palatally displaced upper lateral incisors

4 0 - 4 3

small upper second prenio lars  3 1 ,  52

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D

Bracket system versatility,

  continued

tubes

lower first molar double 53

lower first molar non-convertible 53

lower second molar, use for upper

first/second mola rs of opp osite side 51

lower second premolar 52

second molar bondable mini lubes 54

upper first molar triple 53

upper second molar, use on first molars 50

Bracket-positioning chart 59 , 61, 68

individualized 63

abnormal incisal edges 64

deep-bite cases 65

lower first premolars 64

open-bile cases 65

premolar extraction cases 65

upper canines 64

recommended chart 63

Brackets

b o n d i n g 6 8 - 6 9

direct 68

indirect 69

esthetic 28

extraction series/translation series 252

identification systems 28

in-OUt specification 31

removal

ceramic brackets 308

metal brackets 308

rhomboidal shape 29

selection 3, 13

size range 28

tip specification 32, 283

torque specification 33-38

torque-in-base 29

upper second premolar 31, 52

'Burning anchorage ' 262

Canines

anchorage control

needs determination 96

vertical 107

bracket design requirements 5

bracket positioning 60, 62

bracket selection determinants 44

arch form 45

overbite 46

premolar extraction cases 46

prominence 46

rapid palatal expansion 46

tip control 46

upper lateral incisor agenesis 47

Class II

adult , molar extractions 206-215

deep bile , upper f irsl premo lars and all

third molar extractions 18 4-19 1

non-extraction 192

non-extraction twinblock 198-205

Class

  111

 2 3 5 - 2 4 7

non-extraction, crowding 236-241

second molar extraction 242-247

first premolar extraction 120-126

adu l t 264-271

maximum anchorage deep b i te 146-151

space c losure 26 4-2 77

non-extraction

average angle 1 14-1 19

deep b i te 152-159

high angle requiring upper incisor torque

and lower incisor enamel reduction

2 9 8 - 3 0 3

Case set up 57

full 58

partial 58

patient management 57

Centric relation establish men I 291

Cephalometric radiographs

Class

 111

  cases 219, 220

finishing 293

Ceramic bracket removal 308

Chin cap 233

anterior open bite 143, 144

Chlorhexidine 69

Class I cases 162

arch form 74

high-angle 175, 176

incisor torque 34, 176

see also  Case reports

Class II cases 131, 162-183

anchorage support 172, 173

arch form 74

Arnett analysis 163, 164-165, 168, 169

horizontal overcorrection during finishing

2 8 6 ,

  287

incisor position 162

lower 166

treatment planning 162

upper 166

incisor torque 34, 176

major skeletal disproportion identification

1 6 4 - 1 6 5

molar position 162

planned incisor position (IMP) 162, 166,

168-169

antero-posterio r com pon ent 168

to rque comp onen t 169

surgical/non-surgical decision 163, 164,

175

upper inc iso r movement 170-177

cases with upper anterior spacing 172

d is ta l movement 172-173

following upper premolar extractions 173

mes ia l movem ent 170-17 1

non-extraction cases without spacing 173

to rque con t ro l 174-176

vertical control of maxilla 181

vertical control of upper incisors 177

see also Case studies

Class II elastics

anterior open bite 144

archwire hooks  19

Class II treatment

anchorage support 172, 173

'functional effect' 181

Class III treatment 225

space closure 262

Class

 11/1

  cases 173, 178, 179

anchorage con t ro l needs de te rmina t ion 96

sea l ing 83 , 295

t rea tment p lann ing 164-165

upper incisor movement 170, 172

Class 11/2 cases 177, 178

anchorage control needs determination 97

canine bracket selection 46

mandibular inter-canine width stabili ty

following treatment 72, 73

upper incisor movement 170, 171

Class III cases 131, 162, 219-234

anchorage control needs determination 97

arch form 74

Arnett analysis 220, 221

Class II elastics 225

Class III elastics 2 2 5 ,  230

horiz onta l overcor rection dur ing finishing

286

incisor torque 34, 176

low er inc iso r movement 232-234

distal mandibular repositioning 233

mandibular growth restriction 233

retraction and retroclination 232

unfavorable Class III mandibular growth

234

mandibu la r d isp lacements 219 , 220

maxillary retrognathism 220

treatment t iming 220

mechanics 225

planned incisor position (PIP)

c o m p o n e n t s 2 2 8

upper incisor 226

posterior crowding in development 224

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bracket-positioning chart individualization

64

lacebacks 139, 140

antero-posterio r control 100- 101

retraction in extraction deep-overbite cases

1 3 9 - 1 4 0

torque 36

MIST bracket system values 10- 11

options 44

Case reports

Class I non-extraction 22 -2 3

mild Class U dentally 192 -197

lapered arch form with prominent canine

roo ls 86-91

vertical component 169

positioning lower incisors 178-183

change in A/P position of mandible due to

condyle changes 178, 181, 182

change in length of mandible 178,

180-181

control of antero-poster ior position 178

functional appliances 181

movement of incisors in mandibular bone

17S.

  179

trea tment p lann ing 166-167

incisor position 162, 163

mandibular growth prediction 180

skeletal discrepancy evaluation 220

surgical/non-surgical decision 219, 220,

2 2 2 - 2 2 3

borderline cases 220

late mandibular growth 223

t rea tment p lann ing 219 , 220 , 226-227

lower incisors 2 26

record-taking accuracy 219

upper incisors 226

treatment t iming 220

upper inc iso r movement 229-231

excessive proclination 230

failure to achieve positive overjet 230

320

scanned by LIST team

www.allislam.net

■ ■ ■ > ■ ■

mesia l movement by proclinat ion 229, 230

mesial movement of maxillary bone 229,

231

see also

  Case reports

Class 111  elastics

anterior open bite 144

archwire hooks 19

Class 111  treatment 225, 230

lower arch retraction 261

lower molar antero-posterior control 104

space closure 261

Closing loop archwires  252

Coil spring

HANT/stainless steel wire use 111

space closure with light forces 25 7- 25 8

space  creation, palaially displaced upper

lateral incisors 40, 42, 43

Colored  mo d u le s  selection 112

Computer-a ided design/machining

(CAD-CAM), bracket torque-in-base 29

Contact point 288

Copper nickel-titanium (heat-activated) wires

see HANT w ires

Coronal (lateral) anchorage support 108

Crowding relief,  premolar extrac t ions 250,  251

Curve of Spec 131

final managem ent 288

leveling

archwire placement response 134

second molar banding/bonding  136

Debracketing instrument 308

Decalcificalion spots 310

Deep-bile cases

bracket-positioning chart individualization

65

deepoverbite development 131

extraclion treatment 138-141

leveling and aligning 139-140

space closure 141

use of light forces 139-140, 141

mandibular inter-canine width stability

following treatment 72

non-extraction treatment 134-138

bite-opening curves 137

bite-plate effect 13 4- 13 5

initial archwire placement 134

intermaxillary elastics 138

second molar handing/bonding 136

spacing 138

torque issues 136

partial case set up 58, 109

tooth movements of b i te opening 132 -133

Edgwise appliance

bracket posi t ioning 59

finishing 280

second order ( t ip) bends 283

Elastic chain 254

Elastic retraction mechanics 99

Elastic separators 66

Elastics

overbite contro l 138

sett l ing 294

Elastomeric modules

archwire ligation 20

force levels 255-256

space c losure ac t ive t iebacks 25 5, 25^5-257

trampoline effect 256

Enamel footprin ts 310

Enamel reduction cases 58

Esthetic brackets 28

Esthetic considera t io ns in f in ish ing 2 93

Extraction series brackets 252

Extraction sitegingival overgrowth 259

Eacebows 143, 144

facial profile evaluation during finishing 293

facia l te tragon (East l ight) 174-175, 176

final ad justment appointment 308

Finger and thumb appliances 143

Fin i sh in g 2 8 0 -2 9 6

advantages of preadjusted appliance 280-281

arch form 83, 289

centr ic re la t ion establishment 291

cephalometr ic radiographs 293

contact poin t 288

curve of Spee f inal management 288

definition 281

d y n amic co n s id e ra t io n s 2 9 1 -2 9 2

esthetic considera t ions 293

functional movement checks 291

h o r izo n ta l co n s id e ra t io n s 2 8 2 -2 8 7

horizonta l overcorrect ion 286, 287

incisor crown-shape assessment 283

incisor torque 284

marginal r idge re la t ionships 288

MBT bracket system 21, 281

poster ior torque establishment 289, 290

rota t ion contro l 285

se t t l in g 2 9 4 -2 9 5

space c losure maintenance 286

temporomandibular jo in t function checks

292

tooth f i t coordination 282

influen ce of tip differential 28 3

sp ace clo su re 2 5 2 , 2 5 4 -2 5 8 , 2 5 9

.Straight-Wire Appliance (SWA) 4, 5

functional appliances 181

fu n c t io n a l mo v emen ts 2 9 1

Gauges, bracket posi t io ning 11 , 59 , 61 , 62 , 68

Cingival overgrowth 61 , 259

Gro u p m o v emen t o f t e e th

extraction deep-overbite cases 139

MBT bracket System 16

HANT (heat-ac t ivated n ickel- t i tan ium) wires 13 ,

52 ,  77, 110

arch leveling (torque issues) 136

bendbacks 103

clinical uses 1 10 ,  111

ligation methods 20

opening wires 112

rectangular 78, 113, 136, 288

th in n in g 1 0 3

settling 294

turning in ends 112

I lawley retainers 314

I-Ieadfilms

  2 9 3

Headgear

(Mass II t rea tment anchora ge suppo rt 172,

173

lower arch retraction 261

lower molar antero-poster ior contro l 104

upper molar antero-poster ior contro l 105

vertical control of molars in high-angle cases

107

llerbst appliance 181

High-angle cases

Class I 175, 176

curve of Spee f inal manag eme nt 288

vert ica l contro l of m olars 107

see also

  Case reports

High-pull facebows 143, 144

Horizonta l overcorrect ion 286, 287

Hycon device 258

Identification systems for brackets 28

In-out specif ica t ion 31

Incisors

agenesis of upper lateral 47

anchorage contro l

n eed s d e te rmin a t io n 9 6

a

m

X

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distal tipping of posterio r teeth 133

eruption/extrusion of posterior teeth 132

intrusion of anterior teeth 133

proclination of incisors 133

vertical overcorrection 289

see also

  Case reports

Dentoskeletal structures evalu ation duri ng

finishing 293

'Denture positioning' orthodontics 162, 219

Digit sucking 142

Displaced teeth

bracket positioning 61

partial case set up 58, 109

tooth s ize d iscrepancies 285

transverse considera t ions 289-291

transverse overcorrection 291

vert ica l considera t ions 288-289

vertical crown positions 288

vertical overcorrection 289

follow-up phone cal l 113

Force levels 3, 27

anchorage needs re la t ionship 99

expression of tip 32

extrac t ion deep-overbite cases 139-140, 141

Mclaughlin and Bennett t rea tment approach

MBT bracket system 8, 9, 12, 13

vertical 106

antero-poster ior posi t ion

bendbac ks for contro l 102 -103

evaluation during f in ish ing 293

bracket design requirements 5

bracket posi t ioning 60 , 62

chart indiv idualiza t ion with abnormal

incisal edges 64

rotated incisors  6 1

Class II t rea tmen t 166, 170 -17 3, 17 4-1 76

crown-shape assessment 283

lower

bracket zero tip  4 8

Class  111  t rea tmen t 2 2 6 , 2 3 2 -2 3 4

321

scanned by UST team

w w w . a lhs lam. ne t

Incisors,

 continued

interchangeable brackets 48

re lapse prevention 83

pala ta l ly d isp laced upper la tera l 40-43

planned position (PIP) 96, 162, 166

proclination for deep-overbite correction 133

retraction 250, 251

extraction deep-overbite cases 139

space closure 261

to rq u e 3 4 -3 5

Class II lower incisor posi tion 179

compensation 175

Fastlight's facial tetragon 174-175, 176

finishing 284, 293

treatment planning 162, 168, 226

tr iangular-shaped 58

Individual arch form (1AF) determination 78,

79

Inter-canine widt h 108

Stability following expansion 72-73

')'

  hook headgear 177

Jockey wire 82, 290

Labia l bonded re ta iners 313-314

Lacebacks 7, 111

canine 139, 140

antero-poster ior contro l 100-101

MBT bracket system 8, 15, 16

laser bracket numbering 28

la tera l (coronal) anchorage support 108

Leveling and a l igning 94-113, 131

anchorage control see Anchorage control

Class II treatment 171

definition 94

extraction deep-overbite cases 139-140

mistakes in early preadjusted applian ce

systems 98

patient comfort /acceptance im provem ent

1 1 2 -1 1 3

re-leveling procedures 109

short- term/long-term objectives 94

trea tment sequence 95

wire sequencing 110, 111

Ligature wires

lacebacks see Lacebacks

palatally displaced upper lateral incisors 40

settling 295

Light-cured bonding/cementing mater ia ls 57

Lingual arches

anter ior open b i le 143, 144

length changes 178, 180-182

Class III displacements 219, 220

inter-canine width, stability following

ex p an s io n 7 2 -7 3

plane evaluation during f in ish ing 293

Mandlbu l a r grow th

Class II treatment 180

Class  111  treatment 233, 234

la te growth 223, 234

length changes 180

orthopedic res tr ic t ion 233

Marginal ridge relationships 288

Maxillary expansion 291

see

 also  Rapid maxillary expansion

Maxillary growth 231

MBT bracket system

.022 versus .018 slot 14

anchorage contro l in early trea tment  15

anter ior t ip values 9 , 15 , 99

arch forms 12, 16

archvvire hooks 18-19

archwire l iga t ion methods 20

archwire selection 12

bracket positioning 11

accuracy 13

bracket selection 13

bracket system versatility 13

development from 1993-97 8-11

development from 1997-2001 12

fin ish ing 2 1 , 281

force levels 8, 9, 12, 13

group movement 16

tooth size discrepancies assessement 21

torque values 10-11

trea tment philosophy overview  1 3 - 2 1 ,  2 7

working wires 13, 14, 17

MBT Versatile* bracket system

  see

 MBT bracket

system

Metal bracket removal 308

Metal separators 66

Mid-size metal brackets 28

Mixed dentition cases

functional appliances 181

lingual arches 104

partial case set up 58

Molar bands

anterior open bite 144

lower molar 67

overbite contro l 136

p lacemen t 6 6 -6 7 , 6 9

rapid maxillary expansion (RMF.) 66

removal 310

separa t ion 66

upper molar 66

Molar crossbites 108

Class III treatment 224

tip specification 32, 283

torque 38

trea tment p lanning 162

Mullislrand wires 171

bendbacks 102, 103

opening wires 112

sizes/wire sequencing  110

turning in ends 112

Myofunctional therapy, anter ior open b ite 143,

144

Nickel- t i tan ium coil spring 257-258

Nickel- t i tan ium wires 110

Nola Dry Field system 69

Open-bite cases

bracket-posi t ioning chart indiv idualiza t ion

65

vertical overcorrection 289

see also

 Anterior op en bite

Opening wires 77 , 112

Class II treatment 171

Oral hygiene 69 , 310

Overbite control 131

canine bracket selection 46

I lANT/slainless steel wire use 111

see also

  Deep-bite cases

Overjet reduction ,  I lANT/slainless steel wire use

111

Ovoid arch form 12, 16, 74, 75, 76, 289

archwires 77, 78

assessment 77

Palatal bar

anter ior open b ite 143, 144

Class II t rea tment a nchorage suppo rt 172,

173

Class III maxillary relrognathism 220

lower arch retraction 261

maxil lary expansion m aintena nce 291

molar contro l

antero-poster ior 106

vertical in high-angle cases 107

Palatal bonded retainers 312

Pala ta l expansion 46

anter ior open b ite 143

sett l ing 295

Palatal plate 295

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lower arch retraction 261

lower molar antero-poster ior contro l 104

Lingual bonded retainers 307, 312

Lower arch relapse 317

Mc Laugh l i n and Benne t t t r ea t men t app roac h 7

see also

 MBT bracket system

Mandible

Class II treatment

condylar changes 181, 182, 183

functional appliances 181

Molars

anchorage contro l

needs determination 96

vertical in high-angle cases 107

antero-poster ior contro l

lower 104

upper 105, 106

a t ta ch men ts

  see

  Tubes

bracket positioning 60, 62

eruption of th ird 250, 251

extraction of second

anterior open bite 144

Class II treatment 173

s c anned by L I ST t eam

Partially erupted teeth 61

Patient comfort /acceptance 1 12- 113

Patient post- trea tment le t ter 316

Periodonta l l igament changes 307

Planned incisor position (PIP) 96, 162

Class II t rea tment 166, 168 -169

Class III treatment 226, 228

definition 162

trea tment p lanning 162, 163

Pliers 20

Posit ioners 311

Post- trea tment consulta t ion 316

Post- trea tment pro tocol 316

www.alhslam.net

Posterior bite plates

anterior open bite 143, 144

vertical  control of molars in high-angle cases

107

Preadjusted appliances

Andrews ' system 4- 5

fin ish ing 280-281

Roth  system 6, 8

wire sequencing 110

Premolar extraction cases

bracket-posi t ioning chart indiv idualiza t ion

65

canine bracket selection 46

Class II treatment 173

d eep o v e rb i te 1 3 8 -1 4 1

second premolars 262

space closure 250

space uses 250

see also

  Case reports

Premolars

bracket-posit ioning chart indiv idualiza t ion

64

brackets

interchangeable 49

positioning 60, 62

small upper second premolars 31 , 52

tip specification 32

torque 37, 38

tubes 52

Progress headfilms 293

Rapid maxillary expansion

arch form modifications 80

mandibular inter-canine width stability

following 73

maxillary retrognathism management 220,

231

molar band selection 66

Reciprocal space closure 260

Rectangular .019/.025 steel wires 14, 17, 33, 78,

110

adapta t ion/customization 7 8

bite-opening curves 137

Class II treatment 172, 173

space closure

forces above recommended levels 259

light forces 254, 256

torque issues 136, 284

upper arch expansion 81

Rectangular MANX wires 78, 113, 288

torque issues 136

Rectangular steel wires 110

sizes/wire sequencing 110

Relapse 317

progressive removal 308

white spots 310

Respira tory problems, anter ior open b ite 142,

143

Re ten t io n 3 0 7 , 3 1 2 -3 1 7

arch form considera t ions 83

bonded re ta iners

labia l 313-314

lingual 307, 312

pala ta l 312

long-term considera t ions 317

posit ioners 311

remo v ab le r e ta in e rs 3 1 4 -3 1 5

Reverse headgear 220, 231

Rbomboidal bracket shape 29

Roller coaste r effect 13, 98 , 139

Rotated incisors 61

Rotat ion contro l 285

Roth appliance system 6 , S

Round wires 77 , 110

bendbacks 103

sizes/wire sequencing 110

torque issues 136

Sett l ing 20 , 294-295

posit ioners 311

Size of brackets 28

Skeletal discrepancy evaluation

Class II cases 16 4- 16 5

Class III cases 220

Skeletal structures evaluation during finishing

293

Sliding jig 58

Class II treatment 173

Slid ing mechanics

Class II treatment 172, 173

space closure

heavy (ex-edgewise) forces 252

light forces 254-258

spaces resistant to closure 258

Soft tissue cephalometric analysis (STCA) 163

Space c losure

an ch o rag e co n t ro l 2 6 0 -2 6 2

maximum anchorage cases 260, 261

min im u m an ch o rag e ca se s

 ('burning

anchorage ') 262

archwire hooks 19

Class II treatment 172

closing loop archwires 252

elastic chain 254

extraction deep-overbite cases 141

IlANT/stainless steel wire use 111

ma in ten an ce 2 8 6

m e t h o d s 2 5 2 - 2 5 8

palatally displaced upper lateral incisors 40,

42 ,

  4 3

Split round tube, coil spring reactivation 41

Squ are arch form 12, 16, 74, 75, 76, 81 , 289

archwires 77 , 78

assessment 77

Standard s ize meta l brackets 28

Steel wires 13, 14, 77

clinical uses 110, 111

turning in ends 112

see also

 Rectangular .01 9/ .025 s tee l w ires

Straight-Wire Appliance (SWA) 4, 27

anterior tip specification 4, 8

bracket posi t ioning 59

McLaughlin and Hennett t rea tment approach

7

modif ica t ions 5

'roller coaster effect' 5

Papered arch form   12 ,  16 ,  7 4,  75, 76 , 289

archwires 77, 78

assessment 77

Temporomandibular jo in t dysfunction 292

Tiebacks 13

active 255, 2 56

Class II treatment 172, 173

passive 255, 286

space c losure

dis ta l module 256

extrac t ion deep-overbite cases 141

light forces 255-256

main tenance during f inishing 286

mes ia l mo d u le 2 5 6 -2 5 7

nickel- t i tan ium coil spring 257-258

space s tabil iza tion 19

lip specification  4,  8, 9, 32, 99, 283

anchorage contro l needs re la t ionship 98 , 99

lower incisors bracket zero tip 48

MBT bracket system 9, 15

upper premolar bracket zero t ip 49 , 283

Pornographic radiographs 219

Tongue appliances 144

Tongue habits 142

posit ioners 311

Tonsils removal 143, 144

To o th a l ig n men t ' o r th o d o n t ic s 1 6 2 , 2 1 9

Tooth f i t coordination 282

Tooth s ize d iscrepancies 2 1 , 61 , 285

Torque 5 , 10

arch form modif ica t ions 80

canine 36

expression inefficiency 33-34

I  lAh'P/stainless steel wire use  111

in c i so r 3 4 -3 5

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Re-leveling procedu res 109

Removable acrylic plates 83

Removable retainers 314-315

vacuum-formed 315

wire and acrylic 314

Removal of appliance 307-311

all-at-one-visit 308

bands 310

brackets 308

cement/bonding agents 310

enamel footprints 310

final adjustment appo intm ent 3 08

positioners 311

obstacles 259

over-rapid 252, 253

premolar extrac t ion cases 250

reciprocal 260

slid ing mechanics

heavy (ex-edgewise) forces 252

light forces 254-258

spaces resistant to closure 258

space to relieve crowding 250, 25 I, 260

upper lateral incisor agenesis 47

see also

  Case reports

Space creat ion/s tabil iza t ion

archwire hook uses 19

scanned by LIST team

Class 11  treatment 169, 173, 174-186

co mp en sa t io n   175

Fastlight's facial tetragon 174-175, 176

finishing 284, 293

palatally displaced upper lateral incisors 41

overbite contro l 136

poster ior 289, 290

p remo la r /mo la r

lower  38

u p p e r  3 7

specif ica t ion 33-38

Torque-in-base   29

Torque-in-face 29

www.allislam.net

2

D

Trampoline effect 256

Translation series brackets 252

Transverse overcorreclion 291

Treatment efficacy 3

Treatment goals, 280

Treatment mechanics 3

Treatment p lanning

anchorage contro l needs determination 96

Class II t rea tment 166- 167 , 180

Class  111  treatment 219, 220

'ideal' incisor position 162

limiting features 162, 163

surgical /non-surgical t rea tment 163

tooth s ize d iscrepancies assessement 21

True vertical line (TVI.)

Class II case assessment 168

Class HI case assessment 220 , 221 , 222 , 223

Tu b es

bondable mini tubes 54

molar bands p lacement 67

non-convert ib le 53 , 67

use for upper molars of opposite s ide 51

lower second premolar 52

upper molar

mo la r b an d s p lacemen t 6 6

triple tube 53

use of second molar lubes on f irs t molars

50

see  also

 Bracket system versatility

Twinblock appliance, Class 11/1 treatment case

report 198-205

Unerupted tee th 109

Un wan ted to o th mo v emen ts 9 4

Up-and-down e last ics 19

Upper arch expansion

arch-form settling phase 83

archwires 81

jockey arch use 82

see also

 Palatal expansio n; Rapid m axillary

expansion

Upper arch re lapse 317

Vacuum-formed re ta iners 315

Vert ica l anchorage contro l 106-107

canines 107

incisors 106

molars in h igh-angle cases 107

Vertical chin cups 143, 144

Vert ica l crown posit ions 288

Vertical overcorreclion 289

Vertical triangular elastics 294

Wax bite 219

Wax templates 289

Wax, use by patients 112

Wh i te sp o t s 3 1 0

Wire and acrylic retainers 314

Wires

 se e

  Archwires

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324

scanned by UST team


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