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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
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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.
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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
33
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33
<
33
m
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n
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on
■ - . . ' . ■ ■ •
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"
-\
n
>
n
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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73
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 .
20
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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.
s c anned by U ST t eam
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CASE SS
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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
FH
P o - 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
1 to Mand P lane
8 2
•
/ 7 9 °
3
-
-4
mm
-1 3
mm
0 mm
3 3 °
3 0 °
• 30 °
3 mm
0
mm
1 0 3 °
8 0 °
TO
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Fig. 1.49
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
G o G n S N
F M
M M
1 to A -Po
1 to A-Po
8 2
' 1
- 3
■ 7
- 2
2 9
2 6
2 6
3
1
1
to
M a x P l a n e / 1 0 9
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8 3
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•
m m
m m
m m
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m m
m m
23
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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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.
>
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"D
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>
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-Q
m
Q
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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 .
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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 .
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TORQUE SPECIFICATION
N)
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>
T3
■ o
>
n
m
T3
m
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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 '.
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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
>
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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 .
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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 .
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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
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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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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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>
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r;
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>
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.
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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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T J
>
n
m
<
>
>
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o
>
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m
>
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
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a r ch f o r m
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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.
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Agenesis of upper lateral incisors,
where sp ace is to be closed
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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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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 .
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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
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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
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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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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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N l
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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 .
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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
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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
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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
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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 .
58
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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
u t
CD
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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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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 .
62
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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 .
63
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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 .
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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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o
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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73
w w w . a l l i s l am. ne t
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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w w w . a l l i s l am. ne t
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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CASE AL
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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
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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
0
G o G n S N 4 2
F M / 3 0
M M 3 7
0
«
m m
m m
m m
0
»
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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 .
4 .4 7
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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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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
9 6
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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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O
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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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 .
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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 .
I i_ 4
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 .
112
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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.
114
F i g .
5 .47
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t .B .
Beginn ing
11.5 years
5/10/96
SN A
7 8
S N B / 7 7
A N B
A -N FH
P o - N
FH
W I T S
1
- 2
-6
- 5
G o G n S N / 3 7
F M ;
2 7
M M / 2 9
1
to
A-Po
1
to
A-Po
t o Max P l a n e /
t o M a n d P l a n e /
S
■ 1
1 1 0
7 6
•
•
m m
m m
m m
'
'
'
m m
m m
•
°
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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
■
:
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:
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
Po-N F H
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 M a x P l a n e
t o M a n d P l a n e
7 7 °
7 6 °
1 °
- 3 m m
- 9 m m
- 4 m m
3 9 °
' 2 9 "
32 °
9 m m
6 m m
114 °
88 "
M a n d . S y m p h a s i s
& M a n d . P l a n e
L.B.Begin
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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120
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
Po-N
SN A / 79
S N B
A N B
F H
F H
W I T S
G o G n S N
1 t
1 t
t o M a x
F M
M M
3 A -Po
» A -Po
P lane -
7 6
' 3
- 2
- 4
0
/ 3 6
' 2 7
/ 3 1
6
1.5
1 0 7
»
•
•
m m
m m
m m
°
•
•
m m
m m
'
to Mand Pla ne / 92 '
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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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124
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
^ f l
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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(71
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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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
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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
IM
from
R e l ia nc e o r Tr a n s b on d P lus ™ from 3M Uni t e k a re u s e fu l
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 .
73
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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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r i , i t
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10''-20"of
palatal
root torque
Flat
Lower
- E 3 -
n. i t
Fig.
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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H
O
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
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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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F i g . 6.29
SN A
/ 84 •
S N B
A N B
A N FH
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FH
W I T S
G o G n S N
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M M
1
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1
to Max
P lane
1
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M a n d P l a n e ^
7 8
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6°
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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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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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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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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ss^g= HHBI .
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 .
162
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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
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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.
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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
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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.
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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
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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
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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
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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
III
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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 .
180
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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 .
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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
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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
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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
183
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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
scanned by LIST team
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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
m m
>
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m
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Fig.
7.45
Fig. 7.46
185
Fig. 7.48
Fig. 7.49
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in
23
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>
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H
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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1/1
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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
scanned by LIST team
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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
scanned by LIST team
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The case after appliance removal.
>
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m
>
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
scanned by UST team
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■
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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
scanned by LIST team
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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
scanned by LIST team
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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
scanned by UST team
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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
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O
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m
71
<
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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
www.allislam.net
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
>
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m
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<
m
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33
m
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Fig .
7.172
Fig. 7.171
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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
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F ig .
7 .174
F i g .
7 .175
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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
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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
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F i g . 7 . 1 9 6
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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
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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
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F i g .
7 .198
F i g . 7 .1 9 9
SN A
V SN B
0 \ A N B
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\ Po-N FH
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/ 1 t o Ma x P lane
( 1 t o Ma nd P lane
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' 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 .
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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
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7 .213
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F i g . 7 .219
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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
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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
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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).
22
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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
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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.
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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.
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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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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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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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>
O
<
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23
<
o
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1/1
1/1
23
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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
;
m
w^
^^J
Itetf fetil
M
'
::
'
9 ^
| M
t. •. |
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 .
[7~
•
l l
:
- fit
I
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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 .
250
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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.
254
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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 ,
n
>
n
C/1
I
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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.. -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 '
""O
>
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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■
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 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
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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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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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SN a t S
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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a
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 .
286
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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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X
Z
o
H
X
m
n
m
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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*
2
X
z
-\
x.
m
n
>
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
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Po-N J _ FH
WITS
7 1
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F M / 3 9
M M / 3 7
X to A-Po
1 to A-Po
to
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7
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9 8
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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
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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
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F ig .
1 0 .4 2
10.45
Fig. 10.43
Fig. 10.46
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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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F i g .
1 0 .5 3
302
F i g .
1 0 .5 6
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F ig . 1 0 . 4 8
Fig. 10.49
"Wfe
F ig . 10 .51
F i g .
1 0 . 5 2
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F ig . 10 .54
F i g .
1 0 . 5 5
F ig .
10 .57
S N A
S N B
A N B
A N F H
Po-N FH
W I T S
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F M
M M
1 t o A-Po
1 t o A -Po
1 t o Ma x P lane
1 t o M a n d p l a n e
7 3 °
7 0 °
3 °
- 7 m m
-21 mm
-1 mm
50 *
4 0 "
38 *
8 m m
4 mm
105 •
90 •
303
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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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Labial bo nd ed retainers 31 3
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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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Fig . 11.3 A special debra cket ing in s t ru me nt or o ld l ig ature
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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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
scanned by LIST team
www.allislam.net
•
2
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
7/17/2019 Systemized Orthodontic Treatment Mechanics
http://slidepdf.com/reader/full/systemized-orthodontic-treatment-mechanics 312/312
324
scanned by UST team