Advance Access publication 26 April 2012 Root repair after ......root injury and its sequels may be the most prejudicial for ... key words (mini-implant, mini - screw, micro-implant,

European Journal of Orthodontics 1 of 9 © The Author 2012. Published by Oxford University Press on behalf of the European Orthodontic Society. doi:10.1093/ejo/cjs025 All rights reserved. For permissions, please email: [email protected]

I ntroduction

Suggested as a possibility for skeletal anchorage, the mini-implants were rst introduced in orthodontics by Creekmore and Eklund (1983) for intrusion of the maxillary incisors. Because of their small size, mini-implants can be inserted in different regions of the oral cavity. Mini-implants are contemporary orthodontic adjuncts, mainly used for situations where orthodontic mechanics such as mass movement of teeth, correction of severe overbite, retraction of anterior teeth with no anchorage loss ( Park et al. , 2001 ; Kawakami et al. , 2004 ; Park and Kwon, 2004 ; Nojima et al. , 2006 ), and molar intrusion for correction of open bites and control of the vertical dimension are required ( Umemori et al. , 1999 ; Bae et al. , 2002 ; Park et al. , 2003 ).

However, the use of orthodontic mini-implants can lead to complications such as mini-implant fracture, periimplant mucositis, ulceration of the mucosa , and root injury of the teeth adjacent to the implants. Among these complications, root injury and its sequels may be the most prejudicial for the patient’s dental health and this is the most likely reason why clinicians hesitate to use this device. Kuroda et al. (2007) concluded that the proximity of mini-implants to the

adjacent tooth root is the major risk factor for their failure. Some animal studies showed complete healing of minor damage to root tissue following implant removal, resulting in normal periodontal structure ( Asscherickx et al. , 2005 ; Bae, 2005 ). However, after more extensive injuries, root tissue did not heal fully ( Bae, 2005 ) and that may lead to ankylosis.

It is therefore important for the clinician to understand the potential risks associated with mini-implant use and how to deal with potential complications. The purpose of this study was to systematically review the current literature looking for root damage after contact with mini-implants.

M aterials and methods

The method used in this systematic review was based on the guidelines published in the PRISMA Statement focused on randomized trials and evaluations of interventions ( Moher et al. , 2009 ). The Cochrane Library, Ovid, Scirus, Scopus , and Virtual Health Library (VHL ) databases were utilized to search original articles.

The search strategy included appropriate changes in the key words (mini-implant, mini - screw, micro-implant,

Root repair after contact with mini-implants: systematic review

of the literature

Matheus Alves Jr , Carolina Baratieri , Cláudia Trindade Mattos , Mônica Tirre de Souza Araújo and Lucianne Cople Maia Department of Pediatric Dentistry and Orthodontics, School of Dentistry, Universidade Federal do Rio de Janeiro, Brazil

Correspondence to : Lucianne Cople Maia, Department of Pediatric Dentistry and Orthodontics, School of Dentistry, Universidade Federal do Rio de Janeiro, Avenida Professor Rodolpho Paulo Rocco, 325-Ilha do Fundão, Rio de Janeiro, RJ, CEP: 21941-617, Brazil. E-mail: [email protected]

SUMMARY This systematic review identifi ed and qualifi ed the current evidence of dental root damage and repair after contact with mini-implants. The electronic databases Cochrane library, Ovid, Scirus, Scopus, and Virtual Health Library were used to search original articles from 1980 to December 2011. The inclusion criteria to select the articles were 1. randomized controlled trials and prospective clinical studies based on trials involving humans, 2. randomized controlled studies in animals, 3. use of mini-implants with a diameter less than 2.5 mm, and 4. root contact evaluation associated with the use of orthodontic mini-implants. Two authors independently reviewed and extracted data from the selected studies and a methodological quality assessment process was used to rank the studies classifying them as low moderate or high quality. The searches retrieved 579 citations. After initial selection, 17 studies were considered eligible and their full texts were assessed. Four of those were excluded because root damage was not evaluated and two were excluded because of overlapping samples. Eleven articles, nine in animals and two in humans, fulfi lled the inclusion criteria. From these, two studies were ranked as presenting high methodological quality, eight were judged to be of moderate, and one of low quality. The evidence found suggested that the quality of root repair depends on the amount of damage caused by the mini-implant. When the damage is limited to the cementum or dentin, healing and almost complete and repair of the periodontal structure can occur. Mini-implants that injured the pulp were less likely to result in complete repair of the periodontal tissues.

European Journal of Orthodontics 35 (2013) 491–499doi:10.1093/ejo/cjs025Advance Access publication 26 April 2012

© The Author 2012. Published by Oxford University Press on behalf of the European Orthodontic Society.All rights reserved. For permissions, please email: [email protected]

M. ALVES ET AL.2 of 9

micro-screw, teeth , and root) and followed each database syntax rules.

Furthermore, the following journals were searched manually: American Journal of Orthodontics and Dentofacial Orthopedics, Angle Orthodontist, Clinical Oral Implants Research, and European Journal of Orthodontics. Additionally , the reference lists of the retrieved articles were hand searched for publications that were missed in the database searches.

The inclusion criteria for selection were 1. randomized controlled trials and prospective clinical studies , 2 . randomized controlled studies in animals , 3 . use of mini-implants with a diameter less than 2.5 m m because larger screws would not be used in the interradicular regions , and 4 . root contact evaluation associated with the use of orthodontic mini-implants. The exclusion criteria were technique articles, case reports, opinion articles , and reviews articles. No restrictions were placed on year, publication status, or language.

Table 1 � Quality assessment description according to a modi ed version described by Feldmann and Bondemark (2006) .

Component De nition Classi cation

1. Sample size Number of affected teeth 0 – 10 = 0 point; 11 – 20 = 1 point; ≥ 21 = 2 points 2. Study design Randomized controlled trials (RCTs) and prospective clinical

studies (PS) or randomized controlled studies in animalsRCT = 3 points; PS = 1 point

3. Selection description Description of the evaluated teeth and the characterization of mini-implants (diameter and length)

Teeth or mini-screws description = 1 point; teeth and mini-screws description = 2 point

4. Diagnostic methods Diagnostic methods used to evaluate the tooth after trauma Radiographic = 1 point; histological analysis or scanning electron microscopy = 2 points

5. Post-damage follow-up period Post-trauma evaluation period <3 months = 0 point; ≥ 3 months = 1 point

Figure 1 � Flow diagram of studies selected .

The titles and abstracts of all potentially relevant studies were reviewed. Search results which did not give suf cient information as to their signi cance to this study were also reviewed in full. Authors were contacted directly to obtain additional information when necessary. Each article was reviewed independently by two readers (M.A.J . and C.B . ) and the information obtained was compared. Interexaminer con icts were resolved by discussion of the relevant articles.

Articles that fulfilled the inclusion criteria were methodologically assessed for quality according to a modi ed version described by Feldmann and Bondemark (2006) .

The following ve variables were evaluated: sample size , study design , selection description , diagnostic methods , and follow-up. Adding up the score of the ve variables , each study could maximally score 10 points and be categorized as presenting low (0 – 5 points), moderate (6 – 8 points), or high (9 or 10 points) methodological quality ( Table 1 ).

R esults

Searches of the electronic databases identi ed 579 titles and abstracts on mini-implants and root damage, which were entered into a PRISMA ow diagram ( Figure 1 ). Among these, 265 titles were duplicated and were therefore removed. All remaining titles and abstracts (314) were analy s ed and 294 were found inappropriate and were subsequently excluded. The full texts of 17 studies were assessed and 4 ( Cheng et al. , 2004 ; Kravitz and Kusnoto, 2007 ; Yanosky and Holmes, 2008 ; El-Beialy et al. , 2009 ) studies were excluded because root damage was not evaluated, although the authors had reported complications associated with orthodontic mini-implants in title and/or abstract. Two studies ( Asscherickx et al. , 2008 ; Dao et al. 2009 ) were excluded because they were based on identical samples/showed results similar to another already selected article. Eleven articles ( Asscherickx et al. , 2005 ; Maino et al. , 2007 ; Chen et al. , 2008 ; Kadioglu et al. , 2008 ; Brisceno et al. , 2009 ; Hembree et al. , 2009 ; Kang et al. , 2009 ; Renjen et al. , 2009 ; Lee et al. , 2010 ; Rinaldi and Arana-Chavez 2010 ; Kim and Kim, 2011 ) finally analy s ed ( Table 2 ). Of those 11 articles, 9 were based on animal studies

3 of 9 ROOT REPAIR AFTER CONTACT WITH MINI-IMPLANTS

( Asscherickx et al. , 2005 ; Chen et al. , 2008 ; Brisceno et al. , 2009 ; Hembree et al. , 2009 ; Kang et al. , 2009 ; Renjen et al. , 2009 ; Lee et al. , 2010 ; Rinaldi and Arana-Chavez, 2010 ; Kim and Kim, 2011 ) and 2 were based on human samples ( Maino et al. , 2007 ; Kadioglu et al. , 2008 ).

No additional article was found in the manual search. A detailed summary of the nal selected studies can be found in Table 3 .

Overall, the analy s ed data were based on 56 animals ( Asscherickx et al. , 2005 ; Chen et al. , 2008 ; Brisceno et al. , 2009 ; Hembree et al. , 2009 ; Kang et al. , 2009 ; Renjen et al. , 2009 ; Lee et al. , 2010 ; Rinaldi and Arana-Chavez, 2010 ; Kim and Kim, 2011 ) and 12 patients ( Maino et al. , 2007 ; Kadioglu et al. , 2008 ) and 390 orthodontic mini-implants were used. Only one study ( Lee et al. , 2010 ) did not identify the number of orthodontic mini-implants used. The authors of those articles were contacted to obtain the required information, but no reply was received. The data for implant length and diameter were given in the 11 studies included and ranged from 1.4 to 11.0 and fr o m 1.2 to 2.0 mm, respectively. The damage caused by mini-implants consisted of root perforation, root contact, and periodontal contact; mini-implants were also inserted near the roots of adjacent teeth.

Two studies were of high methodological quality. Brisceno et al. (2009) and Hembree et al. (2009) used the same method to evaluate the healing potential of the roots and surrounding periodontium after intentional damage in the mandible and maxilla from seven beagles dogs, respectively. Fifty-six mini-implants were used in the mandible (49 contacted the roots and 7 were drilled into the roots) and 42 in the maxilla (11 were inserted near the root, 3 contacted the periodontal ligament, 22 contacted the roots , and 6 were drilled into the roots). The trauma duration and the follow-up periods ranged from 0 to 12 weeks.

Eight studies were of moderate methodological quality classi cation ( Asscherickx et al. , 2005 ; Chen et al. , 2008 ; Kadioglu et al. , 2008 ; Kang et al. , 2009 ; Renjen et al. , 2009 ; Lee et al. , 2010 ; Rinaldi and Arana-Chavez, 2010 ; Kim and

Kim, 2011 ). Asscherickx et al. (2005) evaluated the immediate and 25 week s post-insertion effects of 20 mini-implants that were inserted into the mandible of ve beagle dogs. Radiographs were taken and vital stains were administered to posterior histological evaluation. The histological analysis demonstrated that ve mini-implants were inserted near the root and six contacted the root. In another study, Chen et al. (2008) evaluated root repair by using 72 mini-implants inserted in six mongrel dogs. The immediate 3, 12 , and 24 week s post-insertion effects of 27 mini-implants inserted near the root and 45 mini-implants that contacted the root were assessed by histologically. Follow-up was at 12 and 24 weeks. In a human study, Kadioglu et al. (2008) evaluated the premolar root surfaces (20 roots contacted) of 10 patients after intentional contact with 20 mini-implants by scanning electron microscopy. The periods of trauma duration and follow-up were 4 and 8 weeks, respectively. Kang et al. (2009) assessed root damage in three beagle dogs caused by 48 mini-implants. Histological investigation revealed that 24 mini-implants were inserted near the root and 24 had contacted the root. The trauma duration ranged from 1 to 8 weeks and the follow-up periods ranged from 4 to 7 weeks. In one study conducted with minipigs, Kim and Kim (2011) assessed root damage caused by 20 mini-implants that contacted the periodontal ligament ( n = 2), contacted the roots ( n = 24) , and drilled into the roots ( n = 6). Investigation was by histological analysis and the trauma duration ranged from 0 to 16 weeks. Lee et al. (2010) evaluated the root damage caused by mini-implants inserted near the root ( n = 24), in the periodontal ligament ( n = 5), on the root ( n = 8) , and that drilled into the root ( n = 7). Duration of trauma was 16 weeks and investigation was by histolog ical analysis . The authors did not reveal the number of mini-implants used. Renjen et al. (2009) evaluated the effects on the pulp and supporting tissues when mini-implants severely damaged the root surface. The authors used 60 mini-implants in three beagles dogs. The histological analysis showed 11 sites

Table 2 � Quality assessment of the included studies .

References Sample size Study design Selection description Diagnostic methods

Follow-up Total score Judged methodological quality standard

Asscherickx et al. (2005) 1 1 2 2 0 6 Moderate Brisceno et al. (2009) 2 3 2 2 1 10 High Chen et al. (2008) 2 1 2 2 1 8 Moderate Hembree et al. (2009) 2 3 2 2 0 9 High Kang et al. (2009) 2 1 2 2 1 8 Moderate Kadioglu et al. (2008) 1 3 2 2 0 8 Moderate Kim and Kim (2011) 2 1 2 2 0 7 Moderate Lee et al. (2010) 2 1 1 2 0 6 Moderate Maino et al. (2007) 0 1 2 2 0 5 Low Renjen et al. (2009) 1 1 2 2 0 6 Moderate Rinaldi and Arana-Chavez (2010) 2 1 2 2 0 7 Moderate

492 M. ALVES ET AL.


micro-screw, teeth , and root) and followed each database syntax rules.

Furthermore, the following journals were searched manually: American Journal of Orthodontics and Dentofacial Orthopedics, Angle Orthodontist, Clinical Oral Implants Research, and European Journal of Orthodontics. Additionally , the reference lists of the retrieved articles were hand searched for publications that were missed in the database searches.

The inclusion criteria for selection were 1. randomized controlled trials and prospective clinical studies , 2 . randomized controlled studies in animals , 3 . use of mini-implants with a diameter less than 2.5 m m because larger screws would not be used in the interradicular regions , and 4 . root contact evaluation associated with the use of orthodontic mini-implants. The exclusion criteria were technique articles, case reports, opinion articles , and reviews articles. No restrictions were placed on year, publication status, or language.

Table 1 � Quality assessment description according to a modi ed version described by Feldmann and Bondemark (2006) .

Component De nition Classi cation

1. Sample size Number of affected teeth 0 – 10 = 0 point; 11 – 20 = 1 point; ≥ 21 = 2 points 2. Study design Randomized controlled trials (RCTs) and prospective clinical

studies (PS) or randomized controlled studies in animalsRCT = 3 points; PS = 1 point

3. Selection description Description of the evaluated teeth and the characterization of mini-implants (diameter and length)

Teeth or mini-screws description = 1 point; teeth and mini-screws description = 2 point

4. Diagnostic methods Diagnostic methods used to evaluate the tooth after trauma Radiographic = 1 point; histological analysis or scanning electron microscopy = 2 points

5. Post-damage follow-up period Post-trauma evaluation period <3 months = 0 point; ≥ 3 months = 1 point

Figure 1 � Flow diagram of studies selected .

The titles and abstracts of all potentially relevant studies were reviewed. Search results which did not give suf cient information as to their signi cance to this study were also reviewed in full. Authors were contacted directly to obtain additional information when necessary. Each article was reviewed independently by two readers (M.A.J . and C.B . ) and the information obtained was compared. Interexaminer con icts were resolved by discussion of the relevant articles.

Articles that fulfilled the inclusion criteria were methodologically assessed for quality according to a modi ed version described by Feldmann and Bondemark (2006) .

The following ve variables were evaluated: sample size , study design , selection description , diagnostic methods , and follow-up. Adding up the score of the ve variables , each study could maximally score 10 points and be categorized as presenting low (0 – 5 points), moderate (6 – 8 points), or high (9 or 10 points) methodological quality ( Table 1 ).

R esults

Searches of the electronic databases identi ed 579 titles and abstracts on mini-implants and root damage, which were entered into a PRISMA ow diagram ( Figure 1 ). Among these, 265 titles were duplicated and were therefore removed. All remaining titles and abstracts (314) were analy s ed and 294 were found inappropriate and were subsequently excluded. The full texts of 17 studies were assessed and 4 ( Cheng et al. , 2004 ; Kravitz and Kusnoto, 2007 ; Yanosky and Holmes, 2008 ; El-Beialy et al. , 2009 ) studies were excluded because root damage was not evaluated, although the authors had reported complications associated with orthodontic mini-implants in title and/or abstract. Two studies ( Asscherickx et al. , 2008 ; Dao et al. 2009 ) were excluded because they were based on identical samples/showed results similar to another already selected article. Eleven articles ( Asscherickx et al. , 2005 ; Maino et al. , 2007 ; Chen et al. , 2008 ; Kadioglu et al. , 2008 ; Brisceno et al. , 2009 ; Hembree et al. , 2009 ; Kang et al. , 2009 ; Renjen et al. , 2009 ; Lee et al. , 2010 ; Rinaldi and Arana-Chavez 2010 ; Kim and Kim, 2011 ) finally analy s ed ( Table 2 ). Of those 11 articles, 9 were based on animal studies


( Asscherickx et al. , 2005 ; Chen et al. , 2008 ; Brisceno et al. , 2009 ; Hembree et al. , 2009 ; Kang et al. , 2009 ; Renjen et al. , 2009 ; Lee et al. , 2010 ; Rinaldi and Arana-Chavez, 2010 ; Kim and Kim, 2011 ) and 2 were based on human samples ( Maino et al. , 2007 ; Kadioglu et al. , 2008 ).

No additional article was found in the manual search. A detailed summary of the nal selected studies can be found in Table 3 .

Overall, the analy s ed data were based on 56 animals ( Asscherickx et al. , 2005 ; Chen et al. , 2008 ; Brisceno et al. , 2009 ; Hembree et al. , 2009 ; Kang et al. , 2009 ; Renjen et al. , 2009 ; Lee et al. , 2010 ; Rinaldi and Arana-Chavez, 2010 ; Kim and Kim, 2011 ) and 12 patients ( Maino et al. , 2007 ; Kadioglu et al. , 2008 ) and 390 orthodontic mini-implants were used. Only one study ( Lee et al. , 2010 ) did not identify the number of orthodontic mini-implants used. The authors of those articles were contacted to obtain the required information, but no reply was received. The data for implant length and diameter were given in the 11 studies included and ranged from 1.4 to 11.0 and fr o m 1.2 to 2.0 mm, respectively. The damage caused by mini-implants consisted of root perforation, root contact, and periodontal contact; mini-implants were also inserted near the roots of adjacent teeth.

Two studies were of high methodological quality. Brisceno et al. (2009) and Hembree et al. (2009) used the same method to evaluate the healing potential of the roots and surrounding periodontium after intentional damage in the mandible and maxilla from seven beagles dogs, respectively. Fifty-six mini-implants were used in the mandible (49 contacted the roots and 7 were drilled into the roots) and 42 in the maxilla (11 were inserted near the root, 3 contacted the periodontal ligament, 22 contacted the roots , and 6 were drilled into the roots). The trauma duration and the follow-up periods ranged from 0 to 12 weeks.

Eight studies were of moderate methodological quality classi cation ( Asscherickx et al. , 2005 ; Chen et al. , 2008 ; Kadioglu et al. , 2008 ; Kang et al. , 2009 ; Renjen et al. , 2009 ; Lee et al. , 2010 ; Rinaldi and Arana-Chavez, 2010 ; Kim and

Kim, 2011 ). Asscherickx et al. (2005) evaluated the immediate and 25 week s post-insertion effects of 20 mini-implants that were inserted into the mandible of ve beagle dogs. Radiographs were taken and vital stains were administered to posterior histological evaluation. The histological analysis demonstrated that ve mini-implants were inserted near the root and six contacted the root. In another study, Chen et al. (2008) evaluated root repair by using 72 mini-implants inserted in six mongrel dogs. The immediate 3, 12 , and 24 week s post-insertion effects of 27 mini-implants inserted near the root and 45 mini-implants that contacted the root were assessed by histologically. Follow-up was at 12 and 24 weeks. In a human study, Kadioglu et al. (2008) evaluated the premolar root surfaces (20 roots contacted) of 10 patients after intentional contact with 20 mini-implants by scanning electron microscopy. The periods of trauma duration and follow-up were 4 and 8 weeks, respectively. Kang et al. (2009) assessed root damage in three beagle dogs caused by 48 mini-implants. Histological investigation revealed that 24 mini-implants were inserted near the root and 24 had contacted the root. The trauma duration ranged from 1 to 8 weeks and the follow-up periods ranged from 4 to 7 weeks. In one study conducted with minipigs, Kim and Kim (2011) assessed root damage caused by 20 mini-implants that contacted the periodontal ligament ( n = 2), contacted the roots ( n = 24) , and drilled into the roots ( n = 6). Investigation was by histological analysis and the trauma duration ranged from 0 to 16 weeks. Lee et al. (2010) evaluated the root damage caused by mini-implants inserted near the root ( n = 24), in the periodontal ligament ( n = 5), on the root ( n = 8) , and that drilled into the root ( n = 7). Duration of trauma was 16 weeks and investigation was by histolog ical analysis . The authors did not reveal the number of mini-implants used. Renjen et al. (2009) evaluated the effects on the pulp and supporting tissues when mini-implants severely damaged the root surface. The authors used 60 mini-implants in three beagles dogs. The histological analysis showed 11 sites

Table 2 � Quality assessment of the included studies .

References Sample size Study design Selection description Diagnostic methods

Follow-up Total score Judged methodological quality standard

Asscherickx et al. (2005) 1 1 2 2 0 6 Moderate Brisceno et al. (2009) 2 3 2 2 1 10 High Chen et al. (2008) 2 1 2 2 1 8 Moderate Hembree et al. (2009) 2 3 2 2 0 9 High Kang et al. (2009) 2 1 2 2 1 8 Moderate Kadioglu et al. (2008) 1 3 2 2 0 8 Moderate Kim and Kim (2011) 2 1 2 2 0 7 Moderate Lee et al. (2010) 2 1 1 2 0 6 Moderate Maino et al. (2007) 0 1 2 2 0 5 Low Renjen et al. (2009) 1 1 2 2 0 6 Moderate Rinaldi and Arana-Chavez (2010) 2 1 2 2 0 7 Moderate

ROOT REPAIR AFTER CONTACT WITH MINI-IMPLANTS 493

M. ALVES ET AL.4 of 9 Ta

ble

3 � C

hara

cter

istic

s of i

nclu

ded

stud

ies .

Ref

eren

ces

Dia

gnos

tic

met

hods

Num

ber

of a

nim

als/

subj

ects

Num

ber o

f m

ini-i

mpl

ants

Dia

met

er ×

le

ngth

(mm

)Pr

oxim

ity

betw

een

MI

and

dent

al

root

MI

cont

act

with

pe

riodo

ntiu

m

MI

cont

act

with

den

tal

root

Roo

t pe

rfor

atio

n w

ith M

I

Trau

ma

dura

tion

Follo

w-u

pO

utco

mes

Ass

cher

ickx

et

al.

(200

5)

His

tolo

gica

l an

alys

is5

Bea

gles

do

gs20

1.7

× 6.

05

teet

h0

6 te

eth

00.

25 w

eeks

0A

tota

l fai

lure

rate

of 5

5%. S

ix m

ini-

impl

ants

wer

e id

enti

ed

as b

eing

(or

havi

ng b

een)

in c

onta

ct w

ith a

den

tal

root

as o

bser

ved

histo

logi

cally

on

the

seria

l sec

tions

. One

of t

hese

was

still

in

situ

at t

he e

nd o

f the

exa

min

atio

n pe

riod.

For

mat

ion

of se

para

tive

cem

entu

m li

ning

the

root

cou

ld b

e ob

serv

ed. F

or th

e v

e ot

her i

mpl

ants,

w

hich

had

bee

n in

con

tact

with

a

toot

h ro

ot a

nd w

ere

lost

, a d

efec

t in

a to

oth

root

cou

ld b

e ob

serv

ed. A

ll m

ini-i

mpl

ants

plac

ed in

cont

act w

ith a

ro

ot su

rface

and

less

than

1.0

mm

away

fro

m th

e mar

gina

l bon

e lev

el fa

iled.

B

risce

no e

t al.

(200

9)

His

tolo

gica

l an

alys

is7

Bea

gles

do

gs56

1.8

× 8.

00

049

teet

h7

teet

h0

6 an

d 12

wee

ksU

nder

favo

urab

le c

ondi

tions

(n

o in

fect

ion

or p

ulpa

l inv

asio

n),

root

hea

ling

occu

rred

in 6

4.3%

of

the

teet

h af

ter d

amag

e w

ith

min

i-im

plan

ts. In

the

teet

h w

ith

norm

al h

ealin

g, th

e pe

rcen

tage

of

cem

entu

m in

the

defe

ct si

gni

cant

ly

incr

ease

d be

twee

n 6

and

12 w

eeks

. Pa

rtial

or n

o he

alin

g w

as e

vide

nt

for t

eeth

with

pul

pal i

nvas

ion

and

in a

mm

ator

y in l

trate

. C

hen

et a

l. (2

008)

H

isto

logi

cal

anal

ysis

6 M

ongr

el

dogs

722.

0 ×

11.0

27 te

eth

045

teet

h0

0, 3

, 12,

an

d 24

wee

ks12

and

24

wee

ksD

urin

g pl

acem

ent o

f min

i-im

plan

ts

in th

e al

veol

ar p

roce

ss, i

ncre

ased

fa

ilure

rate

s wer

e not

iced

amon

g th

ose

cont

actin

g ad

jace

nt ro

ots.

Faile

d m

ini-s

crew

s app

eare

d to

be

surr

ound

ed w

ith a

gre

ater

vol

ume

of

soft

tissu

e. W

hen

mor

e in a

mm

atio

n w

as p

rese

nt, t

he ad

jace

nt ro

ots s

eem

ed

to e

xper

ienc

e m

ore

reso

rptio

n.

Nev

erth

eles

s, th

e cr

eate

d le

sion

w

as re

paire

d w

ith a

nar

row

zon

e of

m

iner

aliz

ed ti

ssue

dep

osite

d on

the

root

surfa

ce, w

hich

was

like

ly c

ellu

lar

cem

entu

m, a

nd w

as m

ainl

y l

led

with

al

veol

ar b

one,

with

the

perio

dont

al

ligam

ent s

pace

bei

ng m

aint

aine

d.

(Tab

le c

ontin

ues)


Ref

eren

ces

Dia

gnos

tic

met

hods

Num

ber

of a

nim

als/

subj

ects

Num

ber o

f m

ini-i

mpl

ants

Dia

met

er ×

le

ngth

(mm

)Pr

oxim

ity

betw

een

MI

and

dent

al

root

MI

cont

act

with

pe

riodo

ntiu

m

MI

cont

act

with

den

tal

root

Roo

t pe

rfor

atio

n w

ith M

I

Trau

ma

dura

tion

Follo

w-u

pO

utco

mes

Hem

bree

et a

l. (2

009)

H

isto

logi

cal

anal

ysis

7 B

eagl

es

dogs

421.

8 ×

8.0

11 te

eth

3 te

eth

22 te

eth

6 te

eth

0, 6

, and

12

wee

ks0

The

plac

emen

t of m

ini-i

mpl

ants

co

uld

prod

uce

1. im

med

iate

and

ex

tens

ive

dam

age

to p

erio

dont

al

stru

ctur

es, 2

. sho

rt- a

nd lo

ng-te

rm

dam

age

of u

nloa

ded

min

i-im

plan

ts

was

sim

ilar t

o im

med

iate

dam

age,

3.

shor

t- an

d lo

ng-te

rm h

ealin

g w

as e

vide

nt fo

r min

i-im

plan

ts

rem

aini

ng in

con

tact

with

the

toot

h ro

ot, a

nd 4

. in

am

mat

ion

incr

ease

s th

e ris

k of

furth

er d

amag

e ca

used

by

min

i-im

plan

ts.

Kan

g et

al.

(200

9)

His

tolo

gica

l an

alys

is3

Bea

gles

do

gs48

1.8

× 8.

524

teet

h0

24 te

eth

01 –

8 w

eeks

4 – 7

wee

ksA

lthou

gh th

e de

ntal

root

can

be

inju

red

by m

ini-i

mpl

ants

, min

imal

cl

inic

al si

de e

ffect

s are

exp

ecte

d if

the

inju

ry is

not

too

seve

re b

ecau

se

of th

e he

alin

g po

tent

ial o

f su

rrou

ndin

g tis

sues

. K

adio

glu

et a

l. (2

008)

Sc

anni

ng

elec

tron

mic

rosc

opy

10 H

uman

s20

1.5

× 8

00

200

4 an

d 8

wee

ks4

and

8 w

eeks

The

side

root

reso

rptio

ns c

ause

d by

inte

ntio

nal p

rem

olar

ro

ot —

min

i-im

plan

t con

tact

in th

is

stud

y sh

owed

repa

ir an

d he

alin

g w

ithin

a fe

w w

eeks

afte

r rem

oval

of

the

impl

ants

or t

he ti

ppin

g sp

rings

. The

inju

ries w

ere

appa

rent

ly re

paire

d w

ith m

inim

al,

if an

y, c

linic

al c

onse

quen

ces.

Kim

and

Kim

(2

011)

H

isto

logi

cal

anal

ysis

4 M

inip

igs

201.

6 ×

8.0

02

spec

imen

s24

spec

imen

s6

spec

imen

s0,

4, 8

, 12,

an

d 16

wee

ks0

Whe

n th

e ro

ot re

sorb

s aw

ay

from

the

min

i-im

plan

t, ce

men

tum

he

alin

g oc

curs

in m

ost i

nsta

nces

af

ter 1

2 w

eeks

. Whe

n th

e m

ini-i

mpl

ant w

as le

ft in

con

tact

w

ith th

e ro

ot su

rfac

e, m

ostly

due

to

hig

h fo

rce

and

seve

re tr

aum

a to

the

root

dur

ing

min

i-im

plan

t pl

acem

ent,

no h

ealin

g oc

curr

ed.

Whe

n th

e co

nditi

ons w

ere

not

optim

al, r

esor

ptio

n an

d re

pair

did

not o

ccur

. The

dam

age

was

irr

ever

sibl

e w

hen

the

min

i-im

plan

t ru

ptur

ed th

roug

h th

icke

r are

as o

f de

ntin

and

into

pul

p tis

sue.

Tabl

e 3

(Con

tinue

d).

(Tab

le c

ontin

ues)

494 M. ALVES ET AL.


Tabl

e 3 �

Cha

ract

eris

tics o

f inc

lude

d st

udie

s .

Ref

eren

ces

Dia

gnos

tic

met

hods

Num

ber

of a

nim

als/

subj

ects

Num

ber o

f m

ini-i

mpl

ants

Dia

met

er ×

le

ngth

(mm

)Pr

oxim

ity

betw

een

MI

and

dent

al

root

MI

cont

act

with

pe

riodo

ntiu

m

MI

cont

act

with

den

tal

root

Roo

t pe

rfor

atio

n w

ith M

I

Trau

ma

dura

tion

Follo

w-u

pO

utco

mes

Ass

cher

ickx

et

al.

(200

5)

His

tolo

gica

l an

alys

is5

Bea

gles

do

gs20

1.7

× 6.

05

teet

h0

6 te

eth

00.

25 w

eeks

0A

tota

l fai

lure

rate

of 5

5%. S

ix m

ini-

impl

ants

wer

e id

enti

ed

as b

eing

(or

havi

ng b

een)

in c

onta

ct w

ith a

den

tal

root

as o

bser

ved

histo

logi

cally

on

the

seria

l sec

tions

. One

of t

hese

was

still

in

situ

at t

he e

nd o

f the

exa

min

atio

n pe

riod.

For

mat

ion

of se

para

tive

cem

entu

m li

ning

the

root

cou

ld b

e ob

serv

ed. F

or th

e v

e ot

her i

mpl

ants,

w

hich

had

bee

n in

con

tact

with

a

toot

h ro

ot a

nd w

ere

lost

, a d

efec

t in

a to

oth

root

cou

ld b

e ob

serv

ed. A

ll m

ini-i

mpl

ants

plac

ed in

cont

act w

ith a

ro

ot su

rface

and

less

than

1.0

mm

away

fro

m th

e mar

gina

l bon

e lev

el fa

iled.

B

risce

no e

t al.

(200

9)

His

tolo

gica

l an

alys

is7

Bea

gles

do

gs56

1.8

× 8.

00

049

teet

h7

teet

h0

6 an

d 12

wee

ksU

nder

favo

urab

le c

ondi

tions

(n

o in

fect

ion

or p

ulpa

l inv

asio

n),

root

hea

ling

occu

rred

in 6

4.3%

of

the

teet

h af

ter d

amag

e w

ith

min

i-im

plan

ts. In

the

teet

h w

ith

norm

al h

ealin

g, th

e pe

rcen

tage

of

cem

entu

m in

the

defe

ct si

gni

cant

ly

incr

ease

d be

twee

n 6

and

12 w

eeks

. Pa

rtial

or n

o he

alin

g w

as e

vide

nt

for t

eeth

with

pul

pal i

nvas

ion

and

in a

mm

ator

y in l

trate

. C

hen

et a

l. (2

008)

H

isto

logi

cal

anal

ysis

6 M

ongr

el

dogs

722.

0 ×

11.0

27 te

eth

045

teet

h0

0, 3

, 12,

an

d 24

wee

ks12

and

24

wee

ksD

urin

g pl

acem

ent o

f min

i-im

plan

ts

in th

e al

veol

ar p

roce

ss, i

ncre

ased

fa

ilure

rate

s wer

e not

iced

amon

g th

ose

cont

actin

g ad

jace

nt ro

ots.

Faile

d m

ini-s

crew

s app

eare

d to

be

surr

ound

ed w

ith a

gre

ater

vol

ume

of

soft

tissu

e. W

hen

mor

e in a

mm

atio

n w

as p

rese

nt, t

he ad

jace

nt ro

ots s

eem

ed

to e

xper

ienc

e m

ore

reso

rptio

n.

Nev

erth

eles

s, th

e cr

eate

d le

sion

w

as re

paire

d w

ith a

nar

row

zon

e of

m

iner

aliz

ed ti

ssue

dep

osite

d on

the

root

surfa

ce, w

hich

was

like

ly c

ellu

lar

cem

entu

m, a

nd w

as m

ainl

y l

led

with

al

veol

ar b

one,

with

the

perio

dont

al

ligam

ent s

pace

bei

ng m

aint

aine

d.

(Tab

le c

ontin

ues)


Ref

eren

ces

Dia

gnos

tic

met

hods

Num

ber

of a

nim

als/

subj

ects

Num

ber o

f m

ini-i

mpl

ants

Dia

met

er ×

le

ngth

(mm

)Pr

oxim

ity

betw

een

MI

and

dent

al

root

MI

cont

act

with

pe

riodo

ntiu

m

MI

cont

act

with

den

tal

root

Roo

t pe

rfor

atio

n w

ith M

I

Trau

ma

dura

tion

Follo

w-u

pO

utco

mes

Hem

bree

et a

l. (2

009)

H

isto

logi

cal

anal

ysis

7 B

eagl

es

dogs

421.

8 ×

8.0

11 te

eth

3 te

eth

22 te

eth

6 te

eth

0, 6

, and

12

wee

ks0

The

plac

emen

t of m

ini-i

mpl

ants

co

uld

prod

uce

1. im

med

iate

and

ex

tens

ive

dam

age

to p

erio

dont

al

stru

ctur

es, 2

. sho

rt- a

nd lo

ng-te

rm

dam

age

of u

nloa

ded

min

i-im

plan

ts

was

sim

ilar t

o im

med

iate

dam

age,

3.

shor

t- an

d lo

ng-te

rm h

ealin

g w

as e

vide

nt fo

r min

i-im

plan

ts

rem

aini

ng in

con

tact

with

the

toot

h ro

ot, a

nd 4

. in

am

mat

ion

incr

ease

s th

e ris

k of

furth

er d

amag

e ca

used

by

min

i-im

plan

ts.

Kan

g et

al.

(200

9)

His

tolo

gica

l an

alys

is3

Bea

gles

do

gs48

1.8

× 8.

524

teet

h0

24 te

eth

01 –

8 w

eeks

4 – 7

wee

ksA

lthou

gh th

e de

ntal

root

can

be

inju

red

by m

ini-i

mpl

ants

, min

imal

cl

inic

al si

de e

ffect

s are

exp

ecte

d if

the

inju

ry is

not

too

seve

re b

ecau

se

of th

e he

alin

g po

tent

ial o

f su

rrou

ndin

g tis

sues

. K

adio

glu

et a

l. (2

008)

Sc

anni

ng

elec

tron

mic

rosc

opy

10 H

uman

s20

1.5

× 8

00

200

4 an

d 8

wee

ks4

and

8 w

eeks

The

side

root

reso

rptio

ns c

ause

d by

inte

ntio

nal p

rem

olar

ro

ot —

min

i-im

plan

t con

tact

in th

is

stud

y sh

owed

repa

ir an

d he

alin

g w

ithin

a fe

w w

eeks

afte

r rem

oval

of

the

impl

ants

or t

he ti

ppin

g sp

rings

. The

inju

ries w

ere

appa

rent

ly re

paire

d w

ith m

inim

al,

if an

y, c

linic

al c

onse

quen

ces.

Kim

and

Kim

(2

011)

H

isto

logi

cal

anal

ysis

4 M

inip

igs

201.

6 ×

8.0

02

spec

imen

s24

spec

imen

s6

spec

imen

s0,

4, 8

, 12,

an

d 16

wee

ks0

Whe

n th

e ro

ot re

sorb

s aw

ay

from

the

min

i-im

plan

t, ce

men

tum

he

alin

g oc

curs

in m

ost i

nsta

nces

af

ter 1

2 w

eeks

. Whe

n th

e m

ini-i

mpl

ant w

as le

ft in

con

tact

w

ith th

e ro

ot su

rfac

e, m

ostly

due

to

hig

h fo

rce

and

seve

re tr

aum

a to

the

root

dur

ing

min

i-im

plan

t pl

acem

ent,

no h

ealin

g oc

curr

ed.

Whe

n th

e co

nditi

ons w

ere

not

optim

al, r

esor

ptio

n an

d re

pair

did

not o

ccur

. The

dam

age

was

irr

ever

sibl

e w

hen

the

min

i-im

plan

t ru

ptur

ed th

roug

h th

icke

r are

as o

f de

ntin

and

into

pul

p tis

sue.

Tabl

e 3

(Con

tinue

d).

(Tab

le c

ontin

ues)



Ref

eren

ces

Dia

gnos

tic

met

hods

Num

ber

of a

nim

als/

subj

ects

Num

ber o

f m

ini-i

mpl

ants

Dia

met

er ×

le

ngth

(mm

)Pr

oxim

ity

betw

een

MI

and

dent

al

root

MI

cont

act

with

pe

riodo

ntiu

m

MI

cont

act

with

den

tal

root

Roo

t pe

rfor

atio

n w

ith M

I

Trau

ma

dura

tion

Follo

w-u

pO

utco

mes

Lee

et a

l. (2

010)

H

isto

logi

cal

anal

ysis

4 B

eagl

es

dogs

—

1.6

× 6.

024

spec

imen

s5

spec

imen

s8

spec

imen

s7

spec

imen

s16

wee

ks0

In th

e ne

ar-r

oot a

nd P

DL

cont

act

grou

ps, t

he in

cide

nce

of ro

ot

reso

rptio

n in

crea

sed

whe

n th

e di

stan

ce b

etw

een

the

min

i-im

plan

t an

d th

e ro

ot w

as le

ss th

an 0

.6 m

m.

In th

e ro

ot p

erfo

ratio

n gr

oup,

root

re

sorp

tion

and

anky

losi

s occ

urre

d on

th

e si

de o

ppos

ite th

e in

serti

on. S

ome

spec

imen

s in

the

PDL

cont

act a

nd

root

con

tact

gro

ups h

ad c

emen

tum

gr

owth

or l

ittle

root

reso

rptio

n in

sp

ite o

f the

min

i-im

plan

t’s b

eing

cl

ose

to th

e ro

ot.

Mai

no e

t al.

(200

7)

His

tolo

gica

l an

alys

is2

Hum

ans

41.

5 ×

80

04

teet

h0

1 w

eek

27 a

nd

30 d

ays

The

resu

lts sh

ow th

at c

onta

ct

betw

een

a de

ntal

root

and

a d

rill,

impl

ant o

r bot

h ca

uses

reso

rptiv

e ro

ot d

amag

e. A

fter d

isco

ntin

uatio

n of

the

cont

act,

how

ever

, rep

air

begi

ns to

occ

ur th

roug

h th

e de

posi

tion

of c

ellu

lar c

emen

tum

. R

enje

n et

al.

(200

9)

His

tolo

gica

l an

alys

is3

Bea

gles

do

gs60

2.0

× 10

.00

011

site

s5

site

s12

wee

ks0

Ther

e w

as n

o ev

iden

ce o

f in a

mm

ator

y in l

trate

or n

ecro

sis

in th

e pu

lp ti

ssue

or a

long

the

inju

red

root

surf

aces

. Rep

arat

ive

cem

entu

m w

as p

rese

nt a

long

the

perip

hery

of e

ach

inju

red

root

and

al

ong

disp

lace

d de

ntin

frag

men

ts in

ap

posi

tion

with

the

PDL.

The

pr

esen

ce o

f wov

en b

one

intim

atel

y re

late

d w

ith m

ini-i

mpl

ant s

uppo

rted

the

osse

oint

egra

tion

of

min

i-im

plan

ts.

Rin

aldi

and

A

rana

-Cha

vez

(201

0)

His

tolo

gica

l an

alys

is24

Wis

tar

rats

481.

2 ×

1.4

00

48 te

eth

021

, 30,

45

, 60,

90

, and

12

0 da

ys

0A

thin

cem

entu

m-li

ke la

yer w

as

form

ed a

t lon

ger t

imes

afte

r im

plan

tatio

n at

the

area

s in

whi

ch

the

perio

dont

al li

gam

ent w

as in

co

ntac

t with

the

impl

ant.

In a

dditi

on,

bone

form

atio

n oc

curr

ed in

the

alve

olar

bon

e in

con

tact

with

the

impl

ant s

urfa

ce, t

hus s

how

ing

that

os

seoi

nteg

ratio

n ac

tual

ly ta

kes p

lace

ar

ound

orth

odon

tic m

ini-i

mpl

ants

w

hen

left

for l

ong

times

.

MI,

min

i-im

plan

t; PD

L, p

erio

dont

al li

gam

ent.

Tabl

e 3

(Con

tinue

d).


with root contacted and 5 with more extensive root damage after 12 weeks.

Rinaldi and Arana-Chavez (2010) described the ultrastructure of the interface between periodontal tissues and titanium mini-implants in rat mandibles of 24 Wistar rats. Forty-eight mini-implants were used for histological analysis and six different periods of trauma (21, 30, 45, 60, 90 , and 120 days) were analy s ed.

One study ( Maino et al. , 2007 ) was of low methodological quality. This pilot study investigated the effects of contact between a drill, a mini-implant, or both and the roots of four upper premolars in two adolescent orthodontic patients by means of histological analysis. Four mini-implants contacted four teeth. The trauma duration was 1 week and the follow-up evaluation was 27 and 30 days.

D iscussion

This systematic review utilized a reproducible search strategy to analy s e the effects and damage caused by the contact or drilling of mini-implants to the dental root. The rst clinical report in the literature using mini-implants for orthodontic anchorage appeared in 1983, when Creekmore and Eklund (1983) used them to intrude maxillary incisors and because of this , we limited our search 1980 to date. To ensure that the most valid and reliable studies were obtained, strict inclusion and exclusion criteria were used.

Of the 11 studies selected, 2 articles were of high methodological quality, 8 were moderate , and 1 study was of low quality. Of the 11 articles selected, 9 were based on animal studies and 2 were based on human samples. A possible explanation for the limited number of human studies are the ethical issues involved as well as the dif culty of the experimental set - up for such a study. All data from the above articles were collected and analy s ed in order to assess the risks and potential for repair after inadvertently contacting a root during the insertion of a mini-implant.

To strengthen the methodological quality, we added the variables ‘ diagnostic methods ’ and ‘ post-damage follow-up period ’ to our methodological assessment. These variables are important in intervention studies in animals that evaluated root damage with orthodontic mini-implants ( Asscherickx et al. , 2005 ; Chen et al. , 2008 ; Brisceno et al. , 2009 ; Hembree et al. , 2009 ; Kang et al. , 2009 ; Renjen et al. , 2009 ; Lee et al. , 2010 ; Rinaldi and Arana-Chavez, 2010 ; Kim and Kim, 2011 ).

In our systematic review, the two studies ( Brisceno et al. , 2009 ; Hembree et al. , 2009 ) that obtained high methodological quality were performed by the same authors using two different sets of beagle dogs. A randomized split-mouth design was used to evaluate the healing potential of the roots and surrounding periodontium [cementum, periodontal ligament (PDL) , and bone] after intentional damage during mini-implant placement. Brisceno et al. (2009) evaluated

the healing 6 and 12 weeks after intentional root damage. Seven skeletally mature male beagle dogs had mini-implants placed into the roots of eight mandibular teeth ( six premolars and two rst molars). After root contact had been veri ed by using insertion torques and radiographs, the mini-implants were immediately removed, and the sites were allowed to heal for 6 or 12 weeks. Damage to the roots and periodontium ranged from mild invasion to the cementum to pulp invasion. New bone, new PDL, and new cementum were observed in 64.3% of the teeth, with signi cant ( P < 0.05) increases in the percentages of the cementum over time. Sequential label l ing con rmed healing at both 6 and 12 weeks. Abnormal healing was found in 35.7 per cent of the teeth; it included lack of PDL and bone regeneration, bone degeneration in the furcation area, ankylosis , and no healing associated with in ammatory in ltrate or pulpal invasion. The only other high quality investigation by Hembree et al. (2009) used the same method of Brisceno et al. (2009) and the authors evaluated the immediate, short-term (left for 6 week s ), and long-term (12 week s ) damage on the roots of the maxillary second, third, and fourth premolars of seven mature beagle dogs. Histological analysis showed damage of 73.8 per cent of the teeth, ranging from displacement of bone into the periodontal ligament to invasion of the pulp chamber. Displacement of bone into the periodontal ligament and direct damage to the periodontal ligament occurred in three (7.2 per cent ) instances. Damage was isolated to the cementum of eight teeth (19.0 per cent ), whereas damage occurred in the dentin of 11 teeth (26.2 per cent ). Loss of bone in the furcation area was evident in three teeth (7.2 per cent ), and severe damage into the pulp occurred in six teeth (14.2 per cent ). No differences in the amounts of damage were evident between the immediate, short-, and long-term groups. Healing often occurred in the cementum around the unloaded mini - screw implant. Unloaded mini-implants that remain in contact with roots of the teeth can show several degrees of healing. In cases that involved perforation of the pulp chamber, some cementum and dentine repair occurred in the short term, despite the position of mini-implants.

Among the eight studies of moderate methodological quality ( Asscherickx et al. , 2005 ; Chen et al. , 2008 ; Kadioglu et al. , 2008 ; Kang et al. , 2009 ; Renjen et al. , 2009 ; Lee et al. , 2010 ; Rinaldi and Arana-Chavez, 2010 ; Kim and Kim, 2011 ), seven were prospective studies based on different animal models with different animals assess the healing responses after contact or proximity of mini-implants to the roots of the adjacent teeth. These studies ( Asscherickx et al. , 2005 ; Chen et al. , 2008 ; Kadioglu et al. , 2008 ; Kang et al. , 2009 ; Renjen et al. , 2009 ; Lee et al. , 2010 ; Rinaldi and Arana-Chavez, 2010 ; Kim and Kim, 2011 ) evaluated the consequences of mini-implants inserted near root, in the periodontal ligament, that contacted the roots and that drilled into the roots. Asscherickx et al. (2005) , Chen et al. (2008) , Kang et al.

496 M. ALVES ET AL.


Ref

eren

ces

Dia

gnos

tic

met

hods

Num

ber

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ects

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t pe

rfor

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n w

ith M

I

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ma

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tion

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mes

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et a

l. (2

010)

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isto

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ysis

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imen

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men

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(Con

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d).


with root contacted and 5 with more extensive root damage after 12 weeks.

Rinaldi and Arana-Chavez (2010) described the ultrastructure of the interface between periodontal tissues and titanium mini-implants in rat mandibles of 24 Wistar rats. Forty-eight mini-implants were used for histological analysis and six different periods of trauma (21, 30, 45, 60, 90 , and 120 days) were analy s ed.

One study ( Maino et al. , 2007 ) was of low methodological quality. This pilot study investigated the effects of contact between a drill, a mini-implant, or both and the roots of four upper premolars in two adolescent orthodontic patients by means of histological analysis. Four mini-implants contacted four teeth. The trauma duration was 1 week and the follow-up evaluation was 27 and 30 days.

D iscussion

This systematic review utilized a reproducible search strategy to analy s e the effects and damage caused by the contact or drilling of mini-implants to the dental root. The rst clinical report in the literature using mini-implants for orthodontic anchorage appeared in 1983, when Creekmore and Eklund (1983) used them to intrude maxillary incisors and because of this , we limited our search 1980 to date. To ensure that the most valid and reliable studies were obtained, strict inclusion and exclusion criteria were used.

Of the 11 studies selected, 2 articles were of high methodological quality, 8 were moderate , and 1 study was of low quality. Of the 11 articles selected, 9 were based on animal studies and 2 were based on human samples. A possible explanation for the limited number of human studies are the ethical issues involved as well as the dif culty of the experimental set - up for such a study. All data from the above articles were collected and analy s ed in order to assess the risks and potential for repair after inadvertently contacting a root during the insertion of a mini-implant.

To strengthen the methodological quality, we added the variables ‘ diagnostic methods ’ and ‘ post-damage follow-up period ’ to our methodological assessment. These variables are important in intervention studies in animals that evaluated root damage with orthodontic mini-implants ( Asscherickx et al. , 2005 ; Chen et al. , 2008 ; Brisceno et al. , 2009 ; Hembree et al. , 2009 ; Kang et al. , 2009 ; Renjen et al. , 2009 ; Lee et al. , 2010 ; Rinaldi and Arana-Chavez, 2010 ; Kim and Kim, 2011 ).

In our systematic review, the two studies ( Brisceno et al. , 2009 ; Hembree et al. , 2009 ) that obtained high methodological quality were performed by the same authors using two different sets of beagle dogs. A randomized split-mouth design was used to evaluate the healing potential of the roots and surrounding periodontium [cementum, periodontal ligament (PDL) , and bone] after intentional damage during mini-implant placement. Brisceno et al. (2009) evaluated

the healing 6 and 12 weeks after intentional root damage. Seven skeletally mature male beagle dogs had mini-implants placed into the roots of eight mandibular teeth ( six premolars and two rst molars). After root contact had been veri ed by using insertion torques and radiographs, the mini-implants were immediately removed, and the sites were allowed to heal for 6 or 12 weeks. Damage to the roots and periodontium ranged from mild invasion to the cementum to pulp invasion. New bone, new PDL, and new cementum were observed in 64.3% of the teeth, with signi cant ( P < 0.05) increases in the percentages of the cementum over time. Sequential label l ing con rmed healing at both 6 and 12 weeks. Abnormal healing was found in 35.7 per cent of the teeth; it included lack of PDL and bone regeneration, bone degeneration in the furcation area, ankylosis , and no healing associated with in ammatory in ltrate or pulpal invasion. The only other high quality investigation by Hembree et al. (2009) used the same method of Brisceno et al. (2009) and the authors evaluated the immediate, short-term (left for 6 week s ), and long-term (12 week s ) damage on the roots of the maxillary second, third, and fourth premolars of seven mature beagle dogs. Histological analysis showed damage of 73.8 per cent of the teeth, ranging from displacement of bone into the periodontal ligament to invasion of the pulp chamber. Displacement of bone into the periodontal ligament and direct damage to the periodontal ligament occurred in three (7.2 per cent ) instances. Damage was isolated to the cementum of eight teeth (19.0 per cent ), whereas damage occurred in the dentin of 11 teeth (26.2 per cent ). Loss of bone in the furcation area was evident in three teeth (7.2 per cent ), and severe damage into the pulp occurred in six teeth (14.2 per cent ). No differences in the amounts of damage were evident between the immediate, short-, and long-term groups. Healing often occurred in the cementum around the unloaded mini - screw implant. Unloaded mini-implants that remain in contact with roots of the teeth can show several degrees of healing. In cases that involved perforation of the pulp chamber, some cementum and dentine repair occurred in the short term, despite the position of mini-implants.

Among the eight studies of moderate methodological quality ( Asscherickx et al. , 2005 ; Chen et al. , 2008 ; Kadioglu et al. , 2008 ; Kang et al. , 2009 ; Renjen et al. , 2009 ; Lee et al. , 2010 ; Rinaldi and Arana-Chavez, 2010 ; Kim and Kim, 2011 ), seven were prospective studies based on different animal models with different animals assess the healing responses after contact or proximity of mini-implants to the roots of the adjacent teeth. These studies ( Asscherickx et al. , 2005 ; Chen et al. , 2008 ; Kadioglu et al. , 2008 ; Kang et al. , 2009 ; Renjen et al. , 2009 ; Lee et al. , 2010 ; Rinaldi and Arana-Chavez, 2010 ; Kim and Kim, 2011 ) evaluated the consequences of mini-implants inserted near root, in the periodontal ligament, that contacted the roots and that drilled into the roots. Asscherickx et al. (2005) , Chen et al. (2008) , Kang et al.



(2009) , and Kim and Kim (2011) reported that when the mini-implants were inserted and removed immediately, evidence of continuous cementum repair was seen along the injured root surface. Asscherickx et al. (2005) , Kang et al. (2009) , Lee et al. (2010) , Renjen et al. (2009) , and Rinaldi and Arana-Chavez (2010) showed similar results when the mini-implants were left in contact with the root. Only one study ( Kim and Kim, 2011 ) presented no normal healing response when the mini-implant was left touching the root. In relation to root perforation, Renjen et al. (2009) did not nd pulp necrosis, external resorption, and ankylosis when mini-implant had penetrated into the pulp space. The authors observed reparative cementum at each injury site. However, Kim and Kim (2011) and Lee et al. (2010) observed that abnormal healing responses were seen when the pulp tissue was ruptured. Moreover , Lee et al. (2010) observed ankylosis and root resorption on the side opposite the mini-implant insertion. There was only one human study ( Kadioglu et al. , 2008 ) among these eight studies classi ed as moderate methodological quality. The authors performed a split-mouth study design and evaluated dental roots contacted by mini-implants. When the mini-implants drilled the roots by accident, with no repair allowed, there was extensive damage to the root surfaces. In the experimental groups, the roots contacted showed reorganization of collagen br e and new br e s after the repair period. Although some resorption lacunae were still discernible after 8 weeks, the collagen br e s fully covered the affected areas.

Only one study ( Maino et al. , 2007 ) was of low methodological quality. This human study revealed that after discontinuation of the contact, repair begins through deposition of cellular cementum. In the site where the root was damaged by the pilot drill, the original contour of the resorption area was evident as well as incomplete repair of the resorption lacunae with cellular cementum. One of the reasons why this study was ranked as showing low methodological quality was its small sample size.

The evidence from this systematic review of the literature revealed that in both studies (animals and humans), roots , which were contacted by a mini-implant , can experience resorption , but after discontinuation of the contact, the roots are repaired showing absence of signi cant damage.

C onclusion

Based on the evidence of the high and the moderate quality reports found, this systematic review suggests that the quality of the root repair depends on the amount of damage caused by the mini-implant. Under favo u rable conditions (no in ammatory in ltrate or pulpal invasion), healing and almost complete repair of the periodontal structure can occur for as long as root damage is limited to the cementum or the dentin. Mini-implants that perforated the pulp space can showed varying degrees of healing .

Funding

This study was supported by CAPES.

References Asscherickx K , Vannet B V , Wehrbein H , Sabzevar M M 2005 Root repair

after injury from miniscrew . Clinical Oral Implants Research 16 : 575 – 578

Asscherickx K , Vannet B V , Wehrbein H , Sabzevar M M 2008 Success rate of miniscrews relative to their position to adjacent roots . European Journal of Orthodontics 30 : 330 – 335

Bae S M 2005 The repair of the root and pulp tissue after intentional root injury by the orthodontic microimplant in dog . PhD Thesis, Kyungpook National University, Daegu, Korea

Bae S M , Park H S , Kyung H M , Kwon O W , Sung J H 2002 Clinical application of micro-implant anchorage . Journal of Clinical Orthodontics 36 : 298 – 302

Brisceno C E , Rossouw P E , Carrilo R , Spears R , Buschang P H 2009 Healing of the roots and surrounding structures after intentional damage with miniscrew implants . American Journal of Orthodontics and Dentofacial Orthopedics 135 : 292 – 301

Chen Y H , Chang H H , Chen Y J , Lee D , Chiang H H , Yao C C J 2008 Root contact during insertion of miniscrews for orthodontic anchorage increases the failure rate: an animal study . Clinical Oral Implants Research 19 : 99 – 106

Cheng S J , Tseng I Y , Lee J J , Kok S H 2004 A prospective study of the risk factors associated with failure of mini-implants used for orthodontic anchorage . International Journal of Oral and Maxillofacial Implants 19 : 100 – 106

Creekmore T D , Eklund M K 1983 The possibility of skeletal anchorage . Journal of Clinical Orthodontics 17 : 266 – 269

Dao V , Renjen R , Prasad H S , Robrer M D , Maganzini A L , Kraut R A 2009 Cementum, pulp, periodontal ligament, and bone response after direct injury with orthodontic anchorage screws: a histomorphologic study in an animal model . Journal Oral of Maxillofacial Surgery 67 : 2440 – 2445

El-Beialy A R , Abou-El-Ezz A M , Attia K H , El-Bialy A M , Mostafa Y A 2009 Loss of anchorage of miniscrews: a 3-dimensional assessment . American Journal of Orthodontics and Dentofacial Orthopedics 136 : 700 – 707

Feldmann I , Bondemark L 2006 Orthodontic anchorage: a systematic review . Angle Orthodontics 76 : 493 – 501

Hembree M , Buschang P H , Carrilo R , Spears R , Rossouw P E 2009 Effects of intentional damage of the roots and surrounding structures with miniscrew implants . American Journal of Orthodontics and Dentofacial Orthopedics 135 : 280.e1 – 280.e9

Kadioglu O , Buyukyilmaz T , Zachrisson B U , Maino B G 2008 Contact damage to root surfaces of premolars touching miniscrews during orthodontic treatment . American Journal of Orthodontics and Dentofacial Orthopedics 134 : 353 – 360

Kang Y G , Kim J Y , Lee Y J , Chung K R , Park Y G 2009 Stability of mini-screws invading the dental roots and their impact on the paradental tissues in beagles . Angle Orthodontics 79 : 248 – 255

Kawakami M , Miyawaki S , Noguchi H , Kirita T 2004 Screw-type implants used as anchorage for lingual orthodontic mechanics: a case of bimaxillary protrusion with second premolar extraction . Angle Orthodontics 74 : 715 – 719

Kim H , Kim T W 2011 Histologic evaluation of root-surface healing after root contact or approximation during placement of mini-implants . American Journal of Orthodontics and Dentofacial Orthopedics 139 : 752 – 760

Kravitz N D , Kusnoto B 2007 Risks and complications of orthodontic miniscrews . American Journal of Orthodontics and Dentofacial Orthopedics 131 : S43 – S51

Kuroda S , Yamada K , Deguchi T , Hashimoto T , Kyung H M , Yamamoto T T 2007 Root proximity is a major factor for screw failure in orthodontic


anchorage . American Journal of Orthodontics and Dentofacial Orthopedics 131 ( Suppl ): S68 – S73

Lee Y K , Kim J W , Baek S H , Kim T W , Chang Y II 2010 Root and bone response to the proximity of a mini-implant under orthodontic loading . Angle Orthodontics 80 : 452 – 458

Maino B G , Weiland F , Attanasi A , Zachrisson B U , Buyukylmaz T 2007 Root damage and repair after contact with miniscrews . Journal of Clinical Orthodontics 41 : 762 – 766

Moher D , Liberati A , Tetzlaff J , Altman DG , The PRISMA Group . 2009 Preferred reporting items for systematic reviews and meta-analyses: The PRISMA Statement . Journal of Clinical Epidemiology 62 : 1006 – 1012

Nojima L I , Nojima M G , Melgaço C A , Costa L F M , Neves J B 2006 Temporary anchorage devices in orthodontics . In: Neves J B (ed.) Esthetics in implantodology . Quintessence , São Paulo , pp. 269 – 282

Park H S , Bae S M , Kyung H M , Sung J H 2001 Micro-implant anchorage for treatment of skeletal Class I bialveolar protrusion . Journal of Clinical Orthodontics 35 : 417 – 422

Park H S , Kwon T G 2004 Sliding mechanics with microscrew implant anchorage . Angle Orthodontics 74 : 703 – 710

Park Y C , Lee S Y , Kim D H , Jee S H 2003 Intrusion of posterior teeth using mini-screw implants . American Journal of Orthodontics and Dentofacial Orthopedics 123 : 690 – 694

Renjen R , Maganzini A L , Rohrer M D , Prasad H S , Kraut R A 2009 Root and pulp response after intentional injury from miniscrew placement . American Journal of Orthodontics and Dentofacial Orthopedics 136 : 708 – 714

Rinaldi J C , Arana-Chavez V E 2010 Ultrastructure of the interface between periodontal tissues and titanium mini-Implants . Angle Orthodontics 80 : 459 – 465

Umemori M , Sugawara J , Mitani H , Nagasaka H , Kawamura H 1999 Skeletal anchorage system for open-bite correction . American Journal of Orthodontics and Dentofacial Orthopedics 115 : 166 – 174

Yanosky M R , Holmes J D 2008 Mini-implant temporary anchorage devices: orthodontic applications . Compendium of Continuing Education in Dentistry 29 : 12 – 20

498 M. ALVES ET AL.


(2009) , and Kim and Kim (2011) reported that when the mini-implants were inserted and removed immediately, evidence of continuous cementum repair was seen along the injured root surface. Asscherickx et al. (2005) , Kang et al. (2009) , Lee et al. (2010) , Renjen et al. (2009) , and Rinaldi and Arana-Chavez (2010) showed similar results when the mini-implants were left in contact with the root. Only one study ( Kim and Kim, 2011 ) presented no normal healing response when the mini-implant was left touching the root. In relation to root perforation, Renjen et al. (2009) did not nd pulp necrosis, external resorption, and ankylosis when mini-implant had penetrated into the pulp space. The authors observed reparative cementum at each injury site. However, Kim and Kim (2011) and Lee et al. (2010) observed that abnormal healing responses were seen when the pulp tissue was ruptured. Moreover , Lee et al. (2010) observed ankylosis and root resorption on the side opposite the mini-implant insertion. There was only one human study ( Kadioglu et al. , 2008 ) among these eight studies classi ed as moderate methodological quality. The authors performed a split-mouth study design and evaluated dental roots contacted by mini-implants. When the mini-implants drilled the roots by accident, with no repair allowed, there was extensive damage to the root surfaces. In the experimental groups, the roots contacted showed reorganization of collagen br e and new br e s after the repair period. Although some resorption lacunae were still discernible after 8 weeks, the collagen br e s fully covered the affected areas.

Only one study ( Maino et al. , 2007 ) was of low methodological quality. This human study revealed that after discontinuation of the contact, repair begins through deposition of cellular cementum. In the site where the root was damaged by the pilot drill, the original contour of the resorption area was evident as well as incomplete repair of the resorption lacunae with cellular cementum. One of the reasons why this study was ranked as showing low methodological quality was its small sample size.

The evidence from this systematic review of the literature revealed that in both studies (animals and humans), roots , which were contacted by a mini-implant , can experience resorption , but after discontinuation of the contact, the roots are repaired showing absence of signi cant damage.

C onclusion

Based on the evidence of the high and the moderate quality reports found, this systematic review suggests that the quality of the root repair depends on the amount of damage caused by the mini-implant. Under favo u rable conditions (no in ammatory in ltrate or pulpal invasion), healing and almost complete repair of the periodontal structure can occur for as long as root damage is limited to the cementum or the dentin. Mini-implants that perforated the pulp space can showed varying degrees of healing .

Funding

This study was supported by CAPES.

References Asscherickx K , Vannet B V , Wehrbein H , Sabzevar M M 2005 Root repair

after injury from miniscrew . Clinical Oral Implants Research 16 : 575 – 578

Asscherickx K , Vannet B V , Wehrbein H , Sabzevar M M 2008 Success rate of miniscrews relative to their position to adjacent roots . European Journal of Orthodontics 30 : 330 – 335

Bae S M 2005 The repair of the root and pulp tissue after intentional root injury by the orthodontic microimplant in dog . PhD Thesis, Kyungpook National University, Daegu, Korea

Bae S M , Park H S , Kyung H M , Kwon O W , Sung J H 2002 Clinical application of micro-implant anchorage . Journal of Clinical Orthodontics 36 : 298 – 302

Brisceno C E , Rossouw P E , Carrilo R , Spears R , Buschang P H 2009 Healing of the roots and surrounding structures after intentional damage with miniscrew implants . American Journal of Orthodontics and Dentofacial Orthopedics 135 : 292 – 301

Chen Y H , Chang H H , Chen Y J , Lee D , Chiang H H , Yao C C J 2008 Root contact during insertion of miniscrews for orthodontic anchorage increases the failure rate: an animal study . Clinical Oral Implants Research 19 : 99 – 106

Cheng S J , Tseng I Y , Lee J J , Kok S H 2004 A prospective study of the risk factors associated with failure of mini-implants used for orthodontic anchorage . International Journal of Oral and Maxillofacial Implants 19 : 100 – 106

Creekmore T D , Eklund M K 1983 The possibility of skeletal anchorage . Journal of Clinical Orthodontics 17 : 266 – 269

Dao V , Renjen R , Prasad H S , Robrer M D , Maganzini A L , Kraut R A 2009 Cementum, pulp, periodontal ligament, and bone response after direct injury with orthodontic anchorage screws: a histomorphologic study in an animal model . Journal Oral of Maxillofacial Surgery 67 : 2440 – 2445

El-Beialy A R , Abou-El-Ezz A M , Attia K H , El-Bialy A M , Mostafa Y A 2009 Loss of anchorage of miniscrews: a 3-dimensional assessment . American Journal of Orthodontics and Dentofacial Orthopedics 136 : 700 – 707

Feldmann I , Bondemark L 2006 Orthodontic anchorage: a systematic review . Angle Orthodontics 76 : 493 – 501

Hembree M , Buschang P H , Carrilo R , Spears R , Rossouw P E 2009 Effects of intentional damage of the roots and surrounding structures with miniscrew implants . American Journal of Orthodontics and Dentofacial Orthopedics 135 : 280.e1 – 280.e9

Kadioglu O , Buyukyilmaz T , Zachrisson B U , Maino B G 2008 Contact damage to root surfaces of premolars touching miniscrews during orthodontic treatment . American Journal of Orthodontics and Dentofacial Orthopedics 134 : 353 – 360

Kang Y G , Kim J Y , Lee Y J , Chung K R , Park Y G 2009 Stability of mini-screws invading the dental roots and their impact on the paradental tissues in beagles . Angle Orthodontics 79 : 248 – 255

Kawakami M , Miyawaki S , Noguchi H , Kirita T 2004 Screw-type implants used as anchorage for lingual orthodontic mechanics: a case of bimaxillary protrusion with second premolar extraction . Angle Orthodontics 74 : 715 – 719

Kim H , Kim T W 2011 Histologic evaluation of root-surface healing after root contact or approximation during placement of mini-implants . American Journal of Orthodontics and Dentofacial Orthopedics 139 : 752 – 760

Kravitz N D , Kusnoto B 2007 Risks and complications of orthodontic miniscrews . American Journal of Orthodontics and Dentofacial Orthopedics 131 : S43 – S51

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Advance Access publication 26 April 2012 Root repair after ......root injury and its sequels may be the most prejudicial for ... key words (mini-implant, mini - screw, micro-implant,

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