do self-ligating brackets increase the efficiency of ... 10.1051/odfen/2013302 j dentofacial anom...

DOI: 10.1051/odfen/2013302 J Dentofacial Anom Orthod 2013;16:402� RODF / EDP Sciences

1

Article received: 03-2013.Accepted for publication: 05-2013.

Do Self-ligating bracketsincrease the efficiency oforthodontic treatment?An evidence-based review.

Padhraig S. FLEMING1, Kevin O’BRIEN2

1Clinical senior lecturer/honorary consultant/Barts and the London School of Medicine

and Dentistry, London, United Kingdom2Professor of orthodontics, School of Dentistry, University of Manchester, Manchester,

UK

Reprint requests to: Padhraig S. Fleming, Barts and the London School of Medicine and

Dentistry, Queen Mary University of London, Institute of dentistry, Turner street, London

E1 2AD, United Kingdom; E-mail: [email protected]

’This article was commissioned by Revue d’Orthopedie dent-faciale. It is an updated

version of a paper by Fleming and O’Brien in the American Journal of Orthodontics and

Dentofacial Orthopedics originally published in January 2013. The paper is reproduced

with permission from Elsevier.’

ABSTRACT

Self-ligating brackets have become increasingly established in orthodontics inrecent decades. While proponents haveprofessed overwhelming advantages ofself-ligation, most notably a reduction in treatment time and a reducedrequirement for extractions, there has been little convincing evidence tosupport many of these claims. In this review the evidence concerning theinfluence of self-ligating brackets on the efficiency of orthodontic treatment isconsidered.

KEY WORDS

Orthodontic Self-ligation

Bracket Efficiency

Address for correspondence:

P. FLEMINGBarts and the London Schoolof Medicine and Dentistry,Queen Mary University of London,Institute of dentistry,Turner street, London E1 2AD, [email protected] available at http://www.jdao-journal.org or http://dx.doi.org/10.1051/odfen/2013302

http://www.jdao-journal.org

http://dx.doi.org/10.1051/odfen/2013302

The Oxford English dictionary de-fines the efficiency of a system asone ‘achieving maximum productivitywith minimum wasted effort or ex-pense’. Orthodontic pioneers havecontinuously sought methods of en-hancing treatment efficiency by at-tempting to reduce the duration oforthodontic treatment and the lengthof orthodontic appointments26. Whilemean treatment times of 1 to 222,27

years are now typical, the drive to re-duce orthodontic treatment durationpersists. A range of techniques andappliances, including surgical techni-ques30; use of vibratory stimulation31,increased customisation of wires andbrackets23, eschewal of integral treat-ment phases32; and routine avoid-

ance of extractions, continue to beproposed with the expressed aim offurthering this progression. The mosthigh profile of these developmentshave been self-ligating brackets(SLBs)33. The theoretical basis for re-duced treatment time with SLBs wasfounded upon both secure, robustengagement facilitating efficient initialalignment and reduced friction accel-erating space closure (Fig. 1). Unfor-tunately, the marketing of SLBs hascourted courtesy with the advocatesof this type of treatment being overlyoptimistic about their potential ef-fects and, consequently, overlookingor ignoring the findings from clinicalresearch studies17,21.

CHAIRSIDE EFFICIENCY AND EASE OF USE

There is plentiful evidence indicat-ing that use of self-ligating systemsresults in a consistent but modestreduction in chair-side time overconventional appliances1,11,25,28,29,33

(Table I). In a meta-analysis2, resultsfrom two comparable studies28,33

were included reporting a mean timesaving of 20 seconds per arch withslide opening compared with ligatureremoval. No significant time differ-

ence was noted, however, for slideclosure and replacement of ligatures.Proponents have suggested savedtime could be availed of to schedulemore patients; increase efficiency;improve patient relations; or alloworal hygiene reinforcement11. How-ever, it could also be argued that asaving of 40 seconds per patient isinsignificant and unlikely to changepractice.

7 mins

1 min12 mins2.5 mins25 sec2.3 mins

1.5 mins

Maijer and Smith (1990)11 SPEEDTM

SPEEDTM

Shivapuja and Berger (1994)12 ActivaTM, EdgelokTM, SpeedTM Elastomerics Steel ligatures

Voudouris (1997)13 InteractwinTM Elastomerics

Elastomerics

Harradine (2001)8 Damon SLTM ElastomericsBerger and Byloff (2001)14 Elastomerics

Turnbull and Birnie (2007)15 Damon 2TM Elastomerics

Paper SLB Conventional mode of ligation Saving

Table IComparative studies of chairside time differences with SLBs and conventional brackets (CBs).

PADHRAIG FLEMING, KEVIN O’BRIEN

2 FLEMING P., O’BRIEN K. Do Self-ligating brackets increase the efficiency oforthodontic treatment? An evidence-based review.

EFFICIENCY OF TREATMENT

Early research examining the rela-tionship between self-ligating brack-ets and overall treatment time wasobservational rather than experimen-

tal4,6. Studies of this nature are invari-ably compromised by the compellingpossibility of selection bias, observerbias and confounding including

Figure 1Alignment of severely crowded maxillary arch on a non-extraction basis can be undertaken with (a-e) or without(f-j) adjunctive use of NiTi coilspring to recreate space for excluded teeth. Alignment is facilitated by wire engage-ment afforded by the secure clip or gate mechanism of the self-ligating bracket.

DO SELF-LIGATING BRACKETS INCREASE THE EFFICIENCY OF ORTHODONTIC TREATMENT? AN EVIDENCE-BASED REVIEW.

Rev Orthop Dento Faciale 2013;16:303. 3

susceptibility to uncontrolled factorsincluding varying operator experienceand preference, differing arch wiresand sequences, and inconsistent ap-pointment intervals. These studieswere most notable for the large dis-crepancy in treatment duration withmean treatments for conventionalbrackets ranging from 23.56 to 314

months. This discrepancy suggeststhat any advantage attributable tobracket type is likely to be dwarfedby extraneous factors including theskills, standards and ability of the op-erator. Nevertheless, the enduringmessage from these studies was

that SLBs were responsible for signif-icantly reducing treatment times andvisits without impairing the occlusaloutcome. This assumption remainedunchallenged until more robust pro-spective research began to emerge 4years later. This prospective researchwas initially restricted to efficiencyduring a snapshot of treatment,including the efficiency of initialorthodontic alignment7,13,15,16,18-20,24

and the rate of orthodontic spaceclosure12,14 however, prospectivestudies encompassing treatment inits entirety have emerged morerecently.

EFFICIENCY OF ARCH ALIGNMENT

A number of prospective studieshave investigated the efficiency of in-itial orthodontic alignment over a peri-od of up to 20 weeks 7,13,15,16,18-20,24.The results from these trials haveconsistently indicated that despitetheir associated costs self-ligatingbrackets may offer no advantagewith respect to treatment efficiency(Table II).

For example, in a prospective ana-lysis of 48 participants, Miles(2005)13 compared alignment effi-ciency wth SmartClipTM and conven-tional twin brackets. SmartClipTM

was found to be no more effective atreducing irregularity during the initialstage of treatment than the conven-tional twin bracket ligated with elas-tomeric modules or stainless steelligatures, with slightly more irregular-ity remaining after initial alignment inthe group treated with SmartClipTM;this was attributed to the rotationalplay allowed by the passive self-ligat-

ing system using a 0.014 inch align-ing NiTi wire. This study was limitedby a small sample size; two-dimen-sional measurement; inclusion ofboth extraction and non-extractioncases; and confinement of measure-ment to the labial segment only.These findings were mirrored byScott et al.24 in a randomized con-trolled trial of Damon 3TM and a con-ventional appliance in subjectstreated with mandibular first premolarextraction. In a further clinical investi-gation of 58 patients, Miles et al.(2006)15 compared efficiency of align-ment and patient comfort related toDamon 2TM and a conventional twinbracket in non-extraction cases, usinga split-mouth study design. At 10week and 20 week intervals the twinbracket had achieved an irregularityindex of 0.2 mm lower than Damon2TM brackets.

Similar findings were reported byPandis et al. (2007)20 in a controlled



Study Methods Subjects Interventions Outcomes

Miles (2005)19

CCT,Observed at10 and 20weeks

48 patients.Mean age 17.1years, 26 male,32 female

Group 1: 24 patientswith SmartClipTM

Group 2: 24 patientswith VictoryTM

- Rate of initial alignmentlower 3-3




- Rate of initial alignmentupper 3-3

- Rate of initial alignmentupper and lower 3-3

- Rate of initial alignmenlower 3-3-Time taken (days) toalign lower arch in 0.019X 0.025” SSW

Miles et al.(2006)20

CCT, split-mouth design,Observed at10 and 20weeks

58 consecutivepatients. Meanage 16.3 years,18 male,40 female

Lower appliancewith Damon 2TM orVictoryTM brackets inalternate quadrants

Pandis et al.(2007)21

CCT,Observeduntil alignmentachieved

54 patients.Mean age 13.7(1.38) years,11 male, 43 female

Group 1: 27 patientswith Damon 2TM

Group 2: 27 patientswith MicroarchTM

-Time taken (days) toalign lower 3-3

Scott et al.(2008)22

RCT,Observed at8 weeks andfollowingmandibularalignment

62 patientsrecruited. Meanage 16.27 (4.47)years, 32 male,30 female

Group 1: 33 patientswith Damon 3TM

Group 2: 29 patientswith SynthesisTM

Fleming et al.(2009)23

RCT,Observed at8 weeks

65 patients.Mean age 16.28(2.68) years,22 male, 43 female

Group 1: 32 patientswith SmartClipTM

Group 2: 33 patientswith VictoryTM

Miles andWeyant (2010)24

RCT,Observed at10.7 weeks

60 patients. 22 male, 38 female

Group 1: 30 patientswith InOvation CTM

Group 2: 30 patientswith ClarityTM

Ong et al.(2010)25

CCT,Observed at10 and 20weeks



Group 1: 40 archeswith Damon3TM

Group 2: 44 archeswith CBs (26VictoryTM, 18MiniDiamondTM)

Pandis et al.(2011)25

RCT,Observed at10 and 20weeks

Group 1: 25 archeswith Damon3TM

Group 2: 25 archeswith MicroarchTM

Table IIComparative studies of the rate of initial orthodontic alignment with SLBs and CBs.



clinical trial involving Damon IITM andMicroarchTM appliances when theyreported no significant differenceoverall in the time taken to align themandibular arch. A further rando-mized controlled trial7 has reportedlittle difference in alignment effi-ciency with an initial aligning wire(0.016 inch NiTi) with SmartClipTM

and Victory TM systems in subjectstreated without extraction. This studyof 65 patients involved three-dimen-sional measurements and encom-passed 11 mandibular contact points.Similarly, no difference in the rate ofalignment could be attributed to cera-mic SLBs compared to ceramic CBsin a further randomized controlledtrial over a period of 10.7 weeks16.Overall, these studies involving 397participants indicate that, if any time

saving does arise from use of self-li-gating brackets, it does not becomeapparent in the initial alignmentphase of treatment. However, allevia-tion of dental irregularity is difficult tomeasure perfectly; most trials havefailed to control for individual meta-bolic variation; confounding may oc-cur due to baseline imbalances; andthe results may have been uninten-tionally biased by inaccurate bracketplacement. In addition, split mouthdesigns may be criticised due to thecomplexity in handling residual mala-lignment between the central inci-sors. Nevertheless, on the basis ofthese prospective studies, it seemsunlikely that self-ligating systemscounterbalance their cost by resultingin more efficient treatment or bettertreatment outcomes.

RATE OF SPACE CLOSURE AND CANINE RETRACTION

This was first investigated by Miles(2007)14 who considered the rate oforthodontic space closure in a split-mouth design negating the influenceof metabolic variation. No statisticaldifference was found between the

appliance types. This study had a re-latively small sample size with 4 of18 subjects failing to complete thestudy. Posted archwires were usedon both sides; this design meant thatrate of space closure on each side

Paper N SLB Treatment time with SLBs Treatment time with CBs

Eberting et al., (2001)17 215 Damon SLTM

Damon SLTM

25 31Harradine (2001)18 60 19.4 23.5

Hamilton et al. (2009)29 762 InOvationTM 15.5 15.8

*Fleming et al., (2010)30 54 SmartClipTM 21 18*DiBiase et al., (2011)31 48 Damon 3TM 24.48 23*Johannson and Lundstrom (2012)32 90 Time 2TM 20.4 18.2

* Prospective study

Table IIISummary of average treatment times in comparative studies of conventional brackets (CBs) and SLBs.



may also not have been completelyindependent of the opposing side.Nevertheless, these findings were re-inforced by Mezomo et al.12 in asplit-mouth RCT comparing the rateof canine retraction with eitherSmartClipTM or GeminiTM brackets onthe canine tooth. Again, no clinically

or statistically appreciable differencein the monthly rate of canine retrac-tion was found; the average monthlyrate of retraction was just 0.06mmmore with the SLB. Again these stu-dies consistently indicate that SLBsmay be of little benefit with respectto treatment efficiency.

OVERALL TREATMENT DURATION

Recently, a large retrospectivestudy29 and a number of RCTs30-32

investigating the duration of ortho-dontic treatment in its entirety havebeen published. The prospective stu-dies were based in hospital or publichealth care settings and comprised atotal of 192 participants (Table III). Allthree studies concluded that treat-ment with SLBs does not result inshorter treatment time. Importantly,they also included assessment ofthe quality of treatment outcomeachieved using the PAR index3,8 orICON score10. No statistical differ-ence in treatment outcome was ob-served in any of the trials. Thesestudies, therefore, indicate that SLBsare neither advantageous nor disad-

vantageous in respect of treatmentduration or outcome. Indeed, meta-analysis of the results from thesestudies indicates that treatmenttimes might even be slightly lengthierwith self-ligation (Fig. 2).

On the basis of this research it isdoubtful whether a fixed appliancesystem may have a significant bear-ing on the duration of orthodontictreatment or on the number of visitsrequired. Moreover, the skill, experi-ence and objectives of the treatingclinician in addition to the dictates ofthe presenting malocclusion are likelyto override any potential difference intreatment efficiency due to brackettype.

CONCLUSION

In total, 9 RCTs have been cited inthis summary. There are also 2 pub-lished systematic reviews on SLBs2,9.It is, therefore, reasonable to assertthat the question of whether SLBs im-prove treatment efficiency has beenparticularly well-researched in the con-text of orthodontic evidence. Further-more, the consistency of the findings

from these prospective studies is re-markable, with none finding that SLBstranslate into enhanced efficiencyeither during one phase of treatmentor during overall therapy.

Therefore, despite the preliminaryfindings from retrospective studies,the contention that SLBs do not im-prove treatment efficiency is compelling,



highlighting the divergence betweenretrospective research and clinical rea-lity. The efficiency of a course oforthodontic treatment is based on acomplex interaction of parameters in-cluding appliance type; co-operation;biological age; and bone remodelling,with biological processes being the ul-timate arbiter dictating the maximumspeed of the process. While technolo-gical advances may sound and look al-luring, osteoclasts are less easily

impressed than clinicians. As our spe-cialty progresses, further technologi-cal advancement, and greaterintrusion from private companies withfinancial backing is inevitable. It is im-portant that a degree of introspectionoccurs and that salutary lessons arelearned when appraising the benefitsof new, heavily-marketed appliancesystems and ‘‘new’ philosophies. Weshould not fall for the ‘‘Emperors NewClothes again’’.

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