Revisión Sistemática Retención

31
Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review) Littlewood SJ, Millett DT, Doubleday B, Bearn DR, Worthington HV This is a reprint of a Cochrane review, prepared and maintained by The Cochrane Collaboration and published in The Cochrane Library 2006, Issue 1 http://www.thecochranelibrary.com Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review) Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

description

Revisión Sistemática

Transcript of Revisión Sistemática Retención

Page 1: Revisión Sistemática Retención

Retention procedures for stabilising tooth position after

treatment with orthodontic braces (Review)

Littlewood SJ, Millett DT, Doubleday B, Bearn DR, Worthington HV

This is a reprint of a Cochrane review, prepared and maintained by The Cochrane Collaboration and published in The Cochrane Library

2006, Issue 1http://www.thecochranelibrary.com

Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 2: Revisión Sistemática Retención

T A B L E O F C O N T E N T S

1HEADER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2PLAIN LANGUAGE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2BACKGROUND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3OBJECTIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3METHODS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7AUTHORS’ CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8ACKNOWLEDGEMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

10CHARACTERISTICS OF STUDIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18DATA AND ANALYSES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Analysis 1.1. Comparison 1 Circumferential supracrestal fiberotomy and removable retainer full time versus removableretainer full time, Outcome 1 Assessment of stability (maxillary). . . . . . . . . . . . . . . . . 20

Analysis 1.2. Comparison 1 Circumferential supracrestal fiberotomy and removable retainer full time versus removableretainer full time, Outcome 2 Assessment of stability (mandibular). . . . . . . . . . . . . . . . 21

Analysis 2.1. Comparison 2 Thick plain canine-to-canine bonded retainer versus thick spiral canine-to-canine bondedretainer, Outcome 1 Survival of retainers (how many failed). . . . . . . . . . . . . . . . . . . 21

Analysis 3.1. Comparison 3 Thick plain canine-to-canine bonded retainer versus thin spiral wire bonded to incisors andcanines, Outcome 1 Survival of retainers (how many failed). . . . . . . . . . . . . . . . . . . 22

Analysis 4.1. Comparison 4 Thick plain canine-to-canine retainer versus removable retainer, Outcome 1 Survival ofretainers (how many failed). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Analysis 5.1. Comparison 5 Thick spiral canine-to-canine bonded retainer versus thin spiral wire bonded to incisors andcanines, Outcome 1 Survival of retainers (how many failed). . . . . . . . . . . . . . . . . . . 23

Analysis 6.1. Comparison 6 Thick spiral canine-to-canine bonded retainer versus removable, Outcome 1 Survival ofretainers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Analysis 7.1. Comparison 7 Thin spiral wire bonded to incisors and canines versus removable retainers, Outcome 1 Survivalof retainers (how many failed). . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Analysis 8.1. Comparison 8 Circumferential supracrestal fiberotomy and removable retainers nights only versus removableretainers nights, Outcome 1 Adverse effects on health (change in epithelial attachment after 6 months). . . . 24

Analysis 8.2. Comparison 8 Circumferential supracrestal fiberotomy and removable retainers nights only versus removableretainers nights, Outcome 2 Adverse effects on health (change in keratinised gingiva after 6 months). . . . . 25

Analysis 9.1. Comparison 9 Hawley retainer versus clear overlay retainer, Outcome 1 Assessment of stability (degree ofsettling). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Analysis 10.1. Comparison 10 Resin versus multistrand bonded retainers, Outcome 1 Survival rate. . . . . . . 2626ADDITIONAL TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27APPENDICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27WHAT’S NEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27HISTORY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28CONTRIBUTIONS OF AUTHORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28DECLARATIONS OF INTEREST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28SOURCES OF SUPPORT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28INDEX TERMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

iRetention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 3: Revisión Sistemática Retención

[Intervention Review]

Retention procedures for stabilising tooth position aftertreatment with orthodontic braces

Simon J Littlewood1 , Declan T Millett2, Bridget Doubleday3 , David R Bearn4, Helen V Worthington5

1Orthodontic Department, St Luke’s Hospital, Bradford, UK. 2Department of Oral Health and Development, University DentalSchool and Hospital, Wilton, Cork, Ireland. 3Orthodontic Department, Glasgow Dental Hospital, Glasgow, UK. 4Orthodontics,University of Dundee Dental School, Dundee, UK. 5Cochrane Oral Health Group, MANDEC, School of Dentistry, The Universityof Manchester, Manchester, UK

Contact address: Simon J Littlewood, Orthodontic Department, St Luke’s Hospital, Little Horton Lane, Bradford, West Yorkshire,BD5 0NA, UK. [email protected].

Editorial group: Cochrane Oral Health Group.Publication status and date: Edited (no change to conclusions), published in Issue 1, 2009.Review content assessed as up-to-date: 10 November 2005.

Citation: Littlewood SJ, Millett DT, Doubleday B, Bearn DR, Worthington HV. Retention procedures for stabilising tooth po-sition after treatment with orthodontic braces. Cochrane Database of Systematic Reviews 2006, Issue 1. Art. No.: CD002283. DOI:10.1002/14651858.CD002283.pub3.

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

A B S T R A C T

Background

Retention is the phase of orthodontic treatment that attempts to keep teeth in the corrected positions after treatment with orthodontic(dental) braces. Without a phase of retention there is a tendency for the teeth to return to their initial position (relapse). To preventrelapse almost every patient who has orthodontic treatment will require some type of retention.

Objectives

To evaluate the effectiveness of different retention strategies used to stabilise tooth position after orthodontic braces.

Search methods

The Cochrane Oral Health Group’s Trials Register, CENTRAL, MEDLINE and EMBASE were searched. Handsearching of orthodonticjournals was undertaken in keeping with the Cochrane Oral Health Group search programme. No language restrictions were applied.Authors of randomised controlled trials (RCTs) were identified and contacted to identify unpublished trials. Most recent search: May2005.

Selection criteria

RCTs on children and adults, who have had retainers fitted or adjunctive procedures undertaken, following orthodontic treatment withbraces to prevent relapse. The outcomes were: how well the teeth were stabilised, survival of retainers, adverse effects on oral health andquality of life.

Data collection and analysis

Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were conducted in duplicate andindependently by two review authors. As no two studies compared the same retention strategies (interventions) it was not possible tocombine the results of any studies.

1Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 4: Revisión Sistemática Retención

Main results

Five trials satisfied the inclusion criteria. These trials all compared different interventions: circumferential supracrestal fiberotomy (CSF)combined with full-time removable retainer versus a full-time removable retainer alone; CSF combined with a nights-only removableretainer versus a nights-only removable retainer alone; removable Hawley retainer versus a clear overlay retainer; multistrand wireretainer versus a ribbon-reinforced resin bonded retainer; and three types of fixed retainers versus a removable retainer. There was weakunreliable evidence, based on data from one trial, that there was a statistically significant increase in stability in both the mandibular(lower) (P < 0.001) and maxillary (upper) anterior segments (P < 0.001) when the CSF was used, compared with when it was notused. There was also weak, unreliable evidence that teeth settle quicker with a Hawley retainer than with a clear overlay retainer after3 months. The quality of the trial reports was generally poor.

Authors’ conclusions

There are insufficient research data on which to base our clinical practice on retention at present. There is an urgent need for highquality randomised controlled trials in this crucial area of orthodontic practice.

P L A I N L A N G U A G E S U M M A R Y

Retention procedures for stabilising tooth position after treatment with orthodontic braces

There is not enough evidence about the effects of different types of retainers to keep teeth in position after the use of orthodonticbraces.

Retention is the phase of orthodontic treatment that attempts to keep teeth in the corrected positions after orthodontic (dental) braces.Without a phase of retention there is a tendency for the teeth to return to their initial position (relapse). To prevent relapse almostevery patient who has orthodontic treatment will require some type of retention. There is a lack of robust evidence on which to baseclinical practice in this area. This review found weak, unreliable evidence that a simple surgical procedure, combined with a retainer,is better than a retainer alone at keeping teeth in the corrected positions after orthodontic braces are removed. There is an urgent needfor high quality randomised controlled trials in this crucial area of orthodontic practice.

B A C K G R O U N D

Retention is the phase of orthodontic treatment that attempts tokeep teeth in the corrected positions after orthodontic (dental)braces. Without a phase of retention there is a tendency for theteeth to return to their initial position. This unfavourable changefrom the corrected position is known as relapse. The true causesof relapse are not fully understood, but are felt to relate to recoilof the fibres that hold the teeth in the jaw bone, pressures fromthe lips, cheeks and tongue, further growth and the way the teethmeet together (Melrose 1998). To minimise relapse almost everypatient who has orthodontic treatment will require some type ofretention. Attitudes to the use of retention have changed over theyears, but there is a shortage of reliable evidence on which to baseclinical practice (Melrose 1998).

Retention can be achieved by placing appliances, called retainers,on the teeth or by undertaking additional or ’adjunctive’ proce-dures to the teeth or the surrounding structures. The retainers can

either be removable, so that the patient can take them out to clean,or fixed to the teeth. There is no recognised duration for retention.However, it has been shown that it takes on average a minimumof 232 days for fibres around the teeth to remodel to the newtooth position (Reitan 1967). However, even if the teeth are heldin position during this period, studies have shown that in the longterm they can show some relapse (Little 1981; Little 1988). Someclinicians, therefore, prefer to retain for longer periods, sometimesindefinitely.

Adjunctive procedures to the teeth (hard tissues) can involve re-shaping them to improve their stability (Boese 1980). Proceduresto the surrounding structures (soft tissues) include cutting the fi-bres around the neck of the tooth, that hold the tooth in the jawbone (Edwards 1988).

In order for retainers or adjunctive techniques to be acceptablethey must keep the teeth in position without doing any harm. Po-

2Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 5: Revisión Sistemática Retención

tentially they could cause damage to the teeth or the surroundingtissues.

This review investigates the effectiveness of different retentionstrategies used to stabilise tooth position after treatment with or-thodontic braces. It does not attempt to identify the causes ofrelapse. This review will look at the effects of retainers whilst inplace, not the long-term effects after they are no longer in use.

O B J E C T I V E S

To evaluate the effectiveness of different retention strategies usedto stabilise tooth position after orthodontic braces.

To test the null hypothesis that there is no difference betweendifferent retention strategies in how well the teeth are stabilised,survival of retainers, adverse effects on oral health and patient’squality of life compared with the alternative hypothesis of a dif-ference.

M E T H O D S

Criteria for considering studies for this review

Types of studies

Randomised and quasi-randomised controlled trials.

Types of participants

Children and adults who have had retainers fitted or adjunc-tive procedures undertaken following treatment with orthodonticbraces. There was no restriction for the presenting malocclusionor type of active orthodontic treatment undertaken. The patientshad to be followed up at least 3 months after completing theirorthodontic treatment.The following were excluded.

• Individuals who had surgical correction of the jaws.• Individuals with a cleft lip or palate or both or other

craniofacial syndrome.• Individuals who had orthodontic treatment based on

extractions alone or the fitting of a passive space maintainer orboth.

Types of interventions

Retainers or adjunctive techniques or both after treatment with or-thodontic braces. Only studies where the full course of orthodon-tic treatment was completed were included - data on retention

strategies at the end of the first phase of treatment, therefore, wereexcluded.

Types of outcome measures

(1) Assessment of how well the teeth were stabilised. This can beassessed by an index of tooth irregularity, for example Little’s index(Little 1981) or how the teeth meet together, using an index suchas the PAR index (Richmond 1992). This assessment had to bemade at least 3 months after the fitting of the retainer or after theadjunctive procedure was carried out or after both.(2) Survival of the retainers. This assessed how long they lastedwithout breaking (in months) or how many times they needed tobe replaced or repaired during wear.(3) Quality of life. This was assessed, for example, in terms ofpatient’s satisfaction.(4) Adverse effects on the health of the:

• teeth (in terms of decay). This was assessed using indices ofdemineralisation;

• surrounding structures (gums and other supportingstructures). These were assessed using periodontal indices orother markers of periodontal disease.

Search methods for identification of studies

For the identification of studies included in, or considered for thisreview, detailed search strategies were developed for each databasesearched. These were based on the search strategy developed forMEDLINE but revised appropriately for each database to takeaccount of differences in controlled vocabulary and syntax rules.The MEDLINE search strategy combined the subject search withphases 1 and 2 of the Cochrane Sensitive Search Strategy for Ran-domised Controlled Trials (RCTs) (as published in Appendix 5b.2in the Cochrane Handbook for Systematic Reviews of Interventions

4.2.5 (updated May 2005)). The subject search used a combina-tion of controlled vocabulary and free text terms and is publishedin Appendix 1.

Databases searched

The following databases were searched:Cochrane Oral Health Group’s Trials Register (to 9 May 2005)The Cochrane Central Register of Controlled Trials (CENTRAL)(The Cochrane Library 2005, Issue 2)MEDLINE (1966 to 9 May 2005)EMBASE (1989 to week 18, 2005).

Language

There was no language restriction and if papers had been found innon-English language journals, these would have been translated.

3Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 6: Revisión Sistemática Retención

Handsearching

The following journals were identified as important to this reviewand the review authors contributed to the handsearching of thesejournals as part of the Cochrane Oral Health Group’s handsearch-ing programme:American Journal of Orthodontics and Dentofacial Orthopedics (for-merly American Journal of Orthodontics)Angle Orthodontist

European Journal of Orthodontics

Journal of Orthodontics (formerly British Journal of Orthodontics).In addition, conference proceedings and abstracts from the BritishOrthodontic Conference and European Orthodontic Conferencewere searched for the same time period as the handsearching.

Checking reference lists

The bibliographies of papers and review articles identified werechecked for studies published outside the handsearched journals.

Personal communication

The first named authors of randomised trials identified were con-tacted. They were sent the protocol for the review and asked forfurther information relevant to the review that was not apparentin the published work. They were also asked if they knew of anyother published or unpublished studies relevant to the review andthat were not included in the list.Date of most recent search May 2005.

Data collection and analysis

The selection of papers, decision about eligibility, quality assess-ment and data extraction were carried out independently, in dupli-cate, by two review authors. Any disagreements were resolved bydiscussion with one of the other two review authors in the team.The quality of eligible trials was assessed using the three qualityitems:

• allocation concealment and generation of therandomisation sequence;

• blinding of patients, clinicians and outcome assessors;• reporting and analysis of withdrawals and drop outs.

Extracted data were entered on a customized data collection form.The following were recorded.

• Citation details of publication, if appropriate.• Participants (sample size, age of subjects).• Interventions:

- type of retainer- type of adjunctive procedure- prescribed and actual duration of retention.

• Presenting condition and treatment:

- presenting malocclusion- appliances used for orthodontic treatment (removable, func-tional, fixed, RME, headgear).

• Quality assessment of paper (see above).• Outcomes:

- assessment of stability- survival of retainers- adverse effects on health- quality of life assessment.Studies were classified according to the type of retention used:

• retainers• adjunctive procedure.

Data synthesis and analysis

For dichotomous outcomes, the estimate of effect of an interven-tion was expressed as risk ratios together with 95% confidence in-tervals. For continuous outcomes, mean differences and 95% con-fidence intervals were used to summarise the data for each group.Clinical heterogeneity was assessed by examining the types ofparticipants, interventions and outcomes in each study with noplanned subgroup analyses. Meta-analyses would have been doneonly if studies of similar comparisons were reporting the sameoutcome measures. Risks ratios would have been combined fordichotomous data, and standardised mean differences for contin-uous data, using a random-effects model. The significance of anydiscrepancies in the estimates of the treatment effects from thedifferent trials would have been assessed by means of Cochran’stest for heterogeneity and any heterogeneity was investigated.

R E S U L T S

Description of studies

See: Characteristics of included studies; Characteristics of excludedstudies; Characteristics of ongoing studies.See table of Characteristics of included studies.See table of Characteristics of excluded studies.The initial search strategy identified 27 studies of which five ful-filled the selection criteria (Årtun 1997; Edwards 1988; Rose 2002;Sauget 1997; Taner 2000). Allocation concealment, blinding andinformation on withdrawals were assessed by two review authorsfor each of the five included papers. There was complete agree-ment for allocation concealment and blinding with 100% agree-ment and Kappa = 1. There was disagreement on one paper withregard to the withdrawals, there being 75% agreement with Kappa= 0.50.There were 21 trials that were excluded for a variety of reasons:

4Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 7: Revisión Sistemática Retención

• follow up was less than the required 3 months (Ahrens1981);

• although retention was involved in the study, there were noappropriate controls during the retention phase (Akkaya 1998;Akkaya 1999; Forsberg 1991; Mossaz-Joëlson 1989;Sandikçioglu 1997; Sims 1976; Wieslander 1984);

• outcome data were not relevant to this review (Barber 1981;Douglass 1990; Odenrick 1991; Owman-Moll 1995;Owman-Moll 1995b);

• study discussed relapse, but not retention strategies(Harradine 1998);

• contact with authors confirmed study to be retrospective(Axelsson 1993; Vecere 1983);

• subjects did not receive any orthodontic treatment(Bergstrom 1973);

• data were at the end of the first phase of treatment only, notat the end of orthodontic treatment (Keeling 1998; Wheeler2002);

• there were insufficient data in the study to allow properstatistical analysis (Larsson 1983; Haydar 1992).

Types of included studies

Two of the studies were randomised (Årtun 1997; Rose 2002)and three were quasi-randomised (Edwards 1988; Sauget 1997;Taner 2000). Data and subjects from a previous smaller trial werereported in the primary references for Årtun 1997 and Edwards1988.

Setting of included studies

Three studies were undertaken in a hospital setting (Rose 2002;Sauget 1997; Taner 2000), one in practice (Årtun 1997) and inone study the setting was unclear (Edwards 1988). The countriesof origin were USA (Årtun 1997; Edwards 1988; Sauget 1997),Germany (Rose 2002) and Turkey (Taner 2000).

Comparisons used in included studies

The following comparisons were evaluated:• circumferential supracrestal fiberotomy (CSF) and

removable retainer (full time) versus removable retainer (fulltime) (Taner 2000);

• three types of fixed retainers and a removable retainer(Årtun 1997);

• CSF and removable retainer (nights only) versus removableretainer (nights only) (Edwards 1988);

• Hawley removable retainer versus clear overlay removableretainer (Sauget 1997);

• multistrand wire versus a direct-bonded polyethyleneribbon-reinforced resin composite for lingual retention (Rose2002).

Outcomes of included studies

The following outcomes were found:• assessment of stability (in terms of relapse) (Årtun 1997;

Edwards 1988; Taner 2000);• assessment of stability (in terms of settling of occlusion)

(Sauget 1997);• adverse effects on health (Årtun 1997; Edwards 1988; Rose

2002; Taner 2000);• survival of retainers (Edwards 1988; Rose 2002);• patient satisfaction (Rose 2002).

Some of the results were provided without standard deviations, orwith data that were not amenable to meta-analysis.

Risk of bias in included studies

See table of Characteristics of included studies.See additional Table 1 ’Quality of included studies.’Methodological quality was assessed on the basis of:

• allocation concealment and generation of therandomisation sequence

• blinding of patients, clinicians and outcome assessors• reporting and analysis of withdrawals and drop outs.

Two studies used adequate allocation concealment and appro-priate generation of randomisation sequence (Årtun 1997; Rose2002). In three studies the interventions were allocated alternately(Edwards 1988; Sauget 1997; Taner 2000).Blinding of the clinicians and patients was not possible in any ofthe studies due to the nature of the research. Blinding of outcomeassessors was not possible in one study (Årtun 1997). When blind-ing of outcome assessors was possible it was used in two studies(Sauget 1997; Taner 2000), but was not mentioned in the othertwo studies (Edwards 1988; Rose 2002).Withdrawals and drop outs were not fully reported and analysedin any study. Personal communication with authors confirmed nowithdrawals or drop outs in three studies (Årtun 1997; Rose 2002;Sauget 1997). The authors of one study confirmed the drop outof one subject (Taner 2000), who was not included in the analysis.In a further study (Edwards 1988) there was an 85% drop out,but this was not fully analysed.

Effects of interventions

Comparison 1: circumferential supracrestal

fiberotomy (CSF) and removable retainer (full time)

versus removable retainer (full time)

This comparison between groups was made in two trials (Edwards1988; Taner 2000). At 1 year after debond the paper reported sta-tistically significant increases in stability in both the mandibular

5Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 8: Revisión Sistemática Retención

(lower) (P < 0.001) and maxillary (upper) anterior segments (P <0.001) when CSF was used (Outcomes 1.1, 1.2). For each com-parison the standard deviations of the two groups were very dif-ferent and it was therefore inappropriate to calculate the standard-ised mean difference and 95% confidence interval. The authorscorrectly used the non-parametric Mann-Whitney test to makethese comparisons. There were also no adverse effects on gingivalor dental health: no change was reported in the sulcular depth andzone of attached gingiva following the surgical procedure. How-ever, no numerical data were presented for this. No assessmentwas made of survival of retainers or patient satisfaction with thetreatment.

Comparisons 2, 3, 4, 5, 6, 7: three types of fixed

retainers and one removable retainer in the lower

arch

These comparisons between groups were made in one trial (Årtun1997). Assessment of stability and assessment of adverse effectswere not possible as no standard deviations were reported in thepaper. The author was contacted but was unable to supply any ad-ditional information. Assessment of the survival of retainers sug-gested there was no difference in survival rates over 3 years forthree types of bonded retainers and one removable retainer (Out-comes 2.1, 3.1, 4.1, 5.1, 6.1, 7.1). However, this could be dueto the relatively small sample size. There were insufficient datato analyse adverse effects on health. No assessment was made ofpatients’ satisfaction with the treatment.

Comparison 8: circumferential supracrestal

fiberotomy (CSF) and removable retainer (nights

only) versus removable retainer (nights only)

This comparison between groups was made in one trial (Edwards1988). It was not possible to extract appropriate data for the assess-ment of stability. There were no significant differences betweenthe health of the tissues over 6 months measured as change in ep-ithelial attachment and change in keratinized gingiva (Outcomes8.1, 8.2). No assessment was made of patients’ satisfaction withthe treatment.

Comparison 9: Hawley versus clear overlay retainer

This comparison between groups was made in one trial (Sauget1997). The Hawley retainer allowed a statistically significantgreater degree of settling than the clear overlay retainer, with amean of difference 6.53 contacts between teeth (95% confidenceinterval (CI) 2.57 to 10.49) after 3 months (Outcome 9.1). Noassessment was made on adverse effects on health, the survival ofretainers, patients’ satisfaction with the treatment.

Comparison 10: resin bonded versus multistrand

This comparison between groups was made in one trial (Rose2002). There was no statistically significant difference, over 2 yearsbetween the failure rate of these retainers. Although a greater per-centage of the resin bonded (ribbon-reinforced) retainers failed(50%) compared to the multistrand wire retainers (10%), the sam-ple size was small and the data related to one operator. No assess-ment was made of the degree of relapse, oral health or patients’satisfaction with the treatment.No data were available from any study on quality of life assessment.No data could be combined or meta-analysis undertaken, due toclinical heterogeneity, as all compared different retention tech-niques.

D I S C U S S I O N

It was not possible to evaluate completely the effectiveness of themany different retention strategies used to stabilise tooth positionafter orthodontic braces. This was due to a shortage of qualitystudies on the subject. Further research is required in this area.However, the limited information obtained in the review will nowbe discussed further.

Five studies were identified that fulfilled the criteria of the review,but only two of them demonstrated adequate randomisation (Årtun 1997; Rose 2002). Therefore, there is an inherent risk of biasin the remaining three studies (Edwards 1988; Sauget 1997; Taner2000); this must be acknowledged when analysing the results ofthese studies.

Future research in this field would ideally demonstrate the follow-ing features:

• adequate allocation concealment and appropriategeneration of randomisation;

• blinding where appropriate (particularly of outcomeassessors);

• adequate reporting and analysis of withdrawals and dropouts;

• a priori sample size calculations;

• follow up for a minimum of 3 months, but ideally for anumber of years, given the nature of the problem; and

• outcomes that include stability, adverse effects on health,survival of retainers if appropriate and particularly some qualityof life assessment (no studies currently exist that take intoaccount the level of patient satisfaction).

6Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 9: Revisión Sistemática Retención

Multistrand or polyethylene ribbon-reinforcedresin composite for lingual retention

One study (Rose 2002) compared the reliability of post-treatment0.0175“ multistrand wire canine to canine retainers with resincomposite reinforced with plasma-treated polyethylene ribbon.This randomised controlled trial (RCT) failed to demonstate asignificant difference in failure rate over 2 years although the sam-ple size was small. Comparing the ribbon reinforced retainer (5out of 10 retainers failed) with the multistrand wire retainer (1out of 10 retainers failed), the risk ratio was 5 (95% confidenceinterval (CI) 0.7 to 35.5; P = 0.11). There were no data reportedon patient satisfaction or oral health, and the degree of relapse wasnot recorded.This was a well designed study, but relates to only one operator.

Effects of circumferential supracrestalfiberotomy (CSF)

(Edwards 1988; Taner 2000).There were two studies identified which compared CSF combinedwith a removable retainer versus a removable retainer alone. In onestudy the removable retainer was worn full time (Taner 2000) andin the other study it was worn at nights only (Edwards 1988).The results would suggest that CSF and a full-time removableretainer provide a clinically significant reduction in relapse (approx2 mm) over 1 year, compared to using a removable retainer alone(Taner 2000). CSF was reported as having no adverse effects ondental or periodontal health. However, no numerical data werereported on this outcome. There was no assessment of the patients’level of satisfaction with this treatment. It should also be noted thatrandomisation was not adequate and allocation bias may exist.The other prospective study comparing CSF and a removableretainer (nights only) with a removable retainer (nights only)(Edwards 1988) cannot be analysed using the stability data pre-sented in the paper. The author was contacted, but no reply wasreceived. There were significant drop outs during the study, andonly the average data for all the initial subjects were reported. Thenumber of drop outs in this study is disappointing, but demon-strates the difficulty of following up orthodontic patients overallseveral years. There was also a risk of allocation bias and the lengthof removable retainer treatment was not controlled. The study sug-gested that CSF had no adverse effects on the periodontal healthcompared to the non-surgical group. However, this finding shouldbe interpreted with caution, because the randomisation was notadequate, allocation bias may exist and there was a high drop-outrate.

Bonded retainers versus removable retainers

(Årtun 1997).

Unfortunately there were insufficient data in the paper to allowanalysis of the effects on stability and dental health of the threetypes of bonded retainer and one removable Hawley retainer. Theauthor was contacted, but was unable to provide any additionaldata. The assessment of survival of the retainers showed there wasno difference between the retainers over 3 years. This could be dueto similar survival rates, but it could also be due to the relativelysmall sample size.

Settling of occlusion

(Sauget 1997).One study looked at settling of the occlusion, which could beconsidered to be a ’beneficial’ type of relapse. This is settling ofthe occlusion during the retention stage that increases the numberof occlusal contacts.The study compared Hawley retainer worn full time with a clearoverlay retainer worn full time for 3 days (except meals) thennightly after that. There was a significantly increased number ofocclusal contacts after 3 months with the Hawley retainer. How-ever, the study did not address whether these increased number ofocclusal contacts were in the correct locations. Contact with theauthors revealed that the patients were allocated alternately so theresults need to be interpreted with caution due to the possibility ofallocation bias. It should also be remembered that the study onlyinvestigated the first 3 months of retention.

A U T H O R S ’ C O N C L U S I O N S

Implications for practice

• There are insufficient research data on which to base ourclinical practice on retention at present.

• There is a suggestion that circumferential supracrestalfiberotomy (CSF) reduces relapse when combined with a full-time removable retainer, when compared to a full-timeremovable retainer alone.

• There is also a suggestion that a Hawley retainer, worn fulltime, allows more settling of the occlusion than a clear overlayretainer, worn at night, after 3 months. However, the evidencefor this is very weak.

All these findings must be interpreted with caution due to thequality of the research. It should be noted that all the includedstudies, except two (Årtun 1997; Rose 2002), deal with upper archretention only. This is surprising, when you consider that lowerlabial segment relapse is common.

7Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 10: Revisión Sistemática Retención

Implications for research

There is an urgent need for high quality randomised controlledtrials in this crucial area of orthodontic practice. Research is re-quired in the following areas:

• to compare different types of retainers (fixed andremovable);

• to compare retainers worn for different lengths of time;

• to compare different adjunctive techniques e.g. CSF, toeach other and to the use of retainers; and

• to find out how long we need to retain teeth for.

Appropriate outcomes to investigate include:

• stability;

• adverse effects on dental and periodontal health;

• survival of retainers; and

• quality of life assessment (no studies currently exist on thisarea).

Retention studies are not easy studies to undertake. Relapse is along-term problem and long-term follow up of patients is practi-cally difficult and financially demanding. However, given that thevast majority of orthodontic patients undergo a phase of retentionthis vital area of orthodontic research should be given priority inthe near future.

A C K N O W L E D G E M E N T S

We would like to thank Jayne Harrison, Sylvia Bickley, EmmaTavender and the rest of the Cochrane Oral Health Group fortheir kind assistance in completing this review.

R E F E R E N C E S

References to studies included in this review

Edwards 1988 {published and unpublished data}∗ Edwards JG. A long-term prospective evaluation ofthe circumferential supracrestal fiberotomy in alleviatingorthodontic relapse. American Journal of Orthodontics and

Dentofacial Orthopedics 1988;93(5):380–7.Edwards JG. A surgical procedure to eliminate rotationalrelapse. American Journal of Orthodontics 1970;57(1):35–46.

Rose 2002 {published data only}

Rose E, Frucht S, Jonas IE. Clinical comparison of amultistranded wire and a direct-bonded polyethyleneribbon-reinforced resin composite used for lingual retention.Quintessence International 2002;33(8):579–83.

Sauget 1997 {published and unpublished data}

Sauget E, Covell DA, Boero RP, Lieber WS. Comparisonof occlusal contacts with use of Hawley and clear overlayretainers. The Angle Orthodontist 1997;67(3):223–30.

Taner 2000 {published and unpublished data}

Taner T, Haydar B, Kavuklu I, Korkmaz A. Short-termeffects of fiberotomy on relapse of anterior crowding.American Journal of Orthodontics and Dentofacial Orthopedics

2000;118(6):617–23.

Årtun 1997 {published and unpublished data}∗ Årtun J, Spadafora AT, Shapiro PA. A 3-year follow-upstudy of various types of orthodontic canine-to-canineretainers. European Journal of Orthodontics 1997;19(5):501–9.Årtun J, Spadafora AT, Shapiro PA, McNeill RW, ChapkoMK. Hygiene status associated with different types of

bonded, orthodontic canine-to-canine retainers. A clinicaltrial. Journal of Clinical Periodontology 1987;14(2):89–94.

References to studies excluded from this review

Ahrens 1981 {published and unpublished data}

Ahrens DG, Shapira Y, Kuftinec MM. An approach torotational relapse. American Journal of Orthodontics 1981;80(1):83–91.

Akkaya 1998 {published data only}

Akkaya S, Lorenzon S, Üçem TT. Comparison of dentalarch and arch perimeter changes between bonded rapid andslow maxillary expansion procedures. European Journal of

Orthodontics 1998;20(3):255–61.

Akkaya 1999 {published data only}

Akkaya S, Lorenzon S, Üçem TT. A comparison of sagittaland vertical effects between bonded rapid and slow maxillaryexpansion procedures. European Journal of Orthodontics

1999;21(2):175–80.

Axelsson 1993 {published and unpublished data}

Axelsson S, Zachrisson BU. Clinical experience with direct-bonded labial retainers. European Journal of Orthodontics

1993;4 (15) (Abs 4):333.

Barber 1981 {published data only}

Barber AF, Sims MR. Rapid maxillary expansion andexternal root resorption in man: a scanning electronmicroscope study. American Journal of Orthodontics 1981;79(6):630–52.

Bergstrom 1973 {published data only}

Bergstrom K, Jensen R, Martensson B. The effect ofsuperior labial frenectomy in cases with midline diastema.American Journal of Orthodontics 1973;63(6):633–38.

8Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 11: Revisión Sistemática Retención

Douglass 1990 {published data only}

Douglass JB, White JG, Mitchell RJ. Clinical acceptabilityof orthodontic retainers fabricated from stored alginateimpressions. American Journal of Orthodontics and

Dentofacial Orthopedics 1990;97(2):93–7.

Forsberg 1991 {published data only}

Forsberg CM, Brattström, Malmberg E, Nord CE. Ligaturewires and elastomeric rings: two methods of ligation,and their association with microbial colonization ofStreptococcus mutans and lactobacilli. European Journal of

Orthodontics 1991;13(5):416–20.

Harradine 1998 {published data only}

Harradine NW, Pearson MH, Toth B. The effect ofextraction of third molars on late lower incisor crowding: arandomized controlled trial. British Journal of Orthodontics

1998;25(2):117–22.

Haydar 1992 {published and unpublished data}

Haydar B, Ciger S, Saatçi, P. Occlusal contact changes afterthe active phase of orthodontic treatment. American Journal

of Orthodontics and Dentofacial Orthopedics 1992;102(1):22–8.

Keeling 1998 {published and unpublished data}

Keeling SD, Wheeler TT, King GJ, Garvan CW, CohenDA, Cabassa S, et al.Anteroposterior skeletal and dentalchanges after early Class II treatment with bionators andheadgear. American Journal of Orthodontics and Dentofacial

Orthopedics 1998;113(1):40–50.

Larsson 1983 {published and unpublished data}

Larsson E, Schmidt G. The effect of the supra-alveolarsoft tissue on the relapse of orthodontic treatment. British

Journal of Orthodontics 1983;10(1):50–2.

Mossaz-Joëlson 1989 {published data only}

Mossaz-Joëlson K, Mossaz CF. Slow maxillary expansion:a comparison between banded and bonded appliances.European Journal of Orthodontics 1989;11(1):67–76.

Odenrick 1991 {published data only}

Odenrick L, Karlander EL, Pierce A, Kretschmar U.Surface resorption following two forms of rapid maxillaryexpansion. European Journal of Orthodontics 1991;13(4):264–70.

Owman-Moll 1995 {published data only}

Owman-Moll P, Kurol J, Lundgren D. Repair oforthodontically induced root resorption in adolescents. The

Angle Orthodontist 1995;65(6):430–10.

Owman-Moll 1995b {published data only}

Owman-Moll P. Orthodontic tooth movement and rootresorption with special reference to force magnitude andduration. A clinical and histological investigation inadolescents. Swedish Dental Journal Supplement 1995;105:1–45.

Sandikçioglu 1997 {published data only}

Sandikçioglu M, Hazar S. Skeletal and dental changes aftermaxillary expansion in the mixed dentition. American

Journal of Orthodontics and Dentofacial Orthopedics 1997;111(3):321–7.

Sims 1976 {published data only}

Sims MR. Reconstitution of the human oxytalan systemduring orthodontic tooth movement. American Journal of

Orthodontics 1976;70(1):38–58.

Stormann 2002 {published data only}

Stormann I, Ehmer U. A prospective randomized study ofdifferent retainer types. Journal of Orofacial Orthopedics

2002;63(1):42–50.

Vecere 1983 {published and unpublished data}

Vecere JW. Extraction space closure stability followingcanine retraction and periodontal surgery. American Journal

of Orthodontics 1983;84(1):89–90.

Wheeler 2002 {published data only}

Wheeler TT, McGorray SP, Dolce C, Taylor MG, King GJ.Effectiveness of early treatment of Class II malocclusion.American Journal of Orthodontics and Dentofacial Orthopedics

2002;121(1):9–17.

Wieslander 1984 {published data only}

Wieslander L. Intensive treatment of severe Class IImalocclusions with a headgear-Herbst appliance in the earlymixed dentition. American Journal of Orthodontics 1984;86(1):1–13.

References to ongoing studies

Millett 2004 {unpublished data only}

Millett, Doubleday, Littlewood, Atak. Multi-centre RCTcomparing lower multi-strand stainless steel wire versuslower vacuum-formed retainer.

O’Brien 2001 {unpublished data only}

O’Brien K, et al.RCT comparing upper and lower vacuum-formed retainers versus upper Hawley and lower bondedretainers.

Williams 2004 {unpublished data only}

Williams, Rowland, Hichens, Hollinghurst, Ewings, Hills,Clark. RCT to compare upper and lower Hawley retainersversus upper and lower vacuum-formed retainers.

Additional references

Jadad 1998Jadad AR. Randomised controlled trials. London: BritishMedical Journal Books, 1998.

Little 1981Little RM, Wallen TR, Riedel RA. Stability and relapse ofmandibular anterior alignment - first premolar extractioncases treated by traditional edgewise orthodontics. American

Journal of Orthodontics 1981;80(4):349–65.

Little 1988Little RM, Riedel RA, Årtun J. An evaluation of changesin mandibular anterior alignment from 10 to 20 yearspostretention. American Journal of Orthodontics and

Dentofacial Orthopedics 1988;93(5):423–8.

Melrose 1998Melrose C, Millett DT. Toward a perspective on orthodonticretention?. American Journal of Orthodontics and Dentofacial

Orthopedics 1998;113(5):507–14.

9Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 12: Revisión Sistemática Retención

Reitan 1967Reitan K. Clinical and histologic observations on toothmovement during and after orthodontic treatment.American Journal of Orthodontics 1967;53(10):721–45.

Richmond 1992Richmond S, Shaw WC, O’Brien KD, Buchanan IB, JonesR, Stephens CD, et al.The development of the PAR Index(Peer Assessment Rating): reliability and validity. European

Journal of Orthodontics 1992;14(2):125–39.

References to other published versions of this review

Littlewood 2004Littlewood SJ, Millett DT, Doubleday B, Bearn DR,Worthington HV. Retention procedures for stabilising toothposition after treatment with orthodontic braces. Cochrane

Database of Systematic Reviews 2004, Issue 1. [Art. No.:CD002283. DOI: 10.1002/14651858.CD002283]

∗ Indicates the major publication for the study

10Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 13: Revisión Sistemática Retención

C H A R A C T E R I S T I C S O F S T U D I E S

Characteristics of included studies [ordered by study ID]

Edwards 1988

Methods Parallel group.Randomisation not appropriate (alternate patients).Blinding not mentioned.Withdrawals not fully reported. Large number of drop outs not analysed.Study duration: 14 years.

Participants n = 320 initially;n = 48 at end of study.Age 10.9 to 14.1 at start of treatment.Inclusion criteria poorly defined - patients who had edgewise fixed appliances.Type of malocclusion not described.

Interventions Circumferential supracrestal fiberotomy (CSF) and a removable retainer at night versus, removable retainerat night for 24 to 40 months

Outcomes Assessment of stability was measured using Little’s index of irregularity - an appropriate index for thisstudy. However, there were insufficient data to allow statistical analysis of this outcome.The author recorded changes in epithelial attachment as a means of assessing any adverse effects on health.There was no quality of life assessment.

Notes Authors were contacted, but no reply was received.

Risk of bias

Item Authors’ judgement Description

Allocation concealment? No C - Inadequate

Rose 2002

Methods Parallel group.Randomisation appropriate.

Participants n = 20.Age 22.4 (SD 9.7)

Interventions Resin-reinforced and multistrand 0.0175“ stainless steel wire

Outcomes Failure rate. No data reported for oral health or patient satisfaction. Relapse was not assessed

Notes Authors were contacted and they confirmed there were no drop outs and that the randomisation techniquewas appropriate

11Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 14: Revisión Sistemática Retención

Rose 2002 (Continued)

Risk of bias

Item Authors’ judgement Description

Allocation concealment? Yes A - Adequate

Sauget 1997

Methods Parallel group.Randomisation technique not appropriate (alternate patients), so reclassified a clinical controlled trial.Blinding used to assess outcome.No withdrawals or drop outs.Study duration: 3 months.

Participants n = 30.Age 13 y 6 m to 42 y 2 m (mean 19 y 6 m).Poorly defined inclusion criteria: completion of orthodontic treatment

Interventions Hawley versus clear overlay retainer.Hawleys prescribed full time except meals and clear overlay prescribed full time for 3 days, except meals,then nights only

Outcomes Assessment of stability was measured in terms of increased occlusal contacts. In this case an increasein occlusal contacts or settling (effectively more relapse) was considered to be favourable. However, thequality of these occlusal contacts was not described.There was no measurement of adverse effects on health or survival of retainers.There was no quality of life assessment.

Notes Contact with authors confirmed interventions were allocated alternately, and there were no drop outs orwithdrawals

Risk of bias

Item Authors’ judgement Description

Allocation concealment? No C - Inadequate

Taner 2000

Methods Parallel groups.Randomisation technique not appropriate (alternate patients) so a clinical controlled trial.Blinding of assessors.1 patient withdrew (personal communication) but not analysed.Study duration: 1 year.

12Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 15: Revisión Sistemática Retención

Taner 2000 (Continued)

Participants n = 23 (11 test, 12 control).Age 12 to 20 (personal communication).Patients who had initial crowding of 2.3 to 25.5mm (Little’s index) and all had had fixed appliances.50% of patients in each group had had extractions as part of treatment

Interventions Circumferential supracrestal fiberotomy (CSF) with a Hawley retainer full time versus Hawley retainerworn full time. Surgery was performed 1 week after debonding. Each patient wore a Hawley within 24hours of debond

Outcomes Assessment of stability was measured using Little’s index of irregularity, which is an appropriate index forthis study.Adverse effects on health were reported in narrative form, but no data were presented for this outcome.There was no quality of life assessment.

Notes Contact from authors confirmed intervention allocated alternately, assessors were blinded, and one subjectwithdrew but no patients dropped out. Age range 12 to 20 years

Risk of bias

Item Authors’ judgement Description

Allocation concealment? No C - Inadequate

Årtun 1997

Methods Parallel group.Randomised with appropriate method of randomisation.Blinding not possible.No withdrawals or drop outs.

Participants n = 49.Age 12 to 55.Inclusion criteria:treated with edgewise fixed appliances by 2 orthodontists in 1 practice, variety of malocclusions. Stratifiedaccording to age (adult/adolescent), gender and gingival condition

Interventions 4 types of retainers: thick, plain 0.032“ stainless steel canine to canine retainer (n = 11); thick spiral 0.032” stainless steel wire canine to canine retainer (n = 13); thin flexible 0.0205“ stainless steel spiral wirebonded to each tooth in labial segment (n = 11); removable retainers (n = 14).At time of placement of retainer all patients were taught correct oral hygiene procedures with toothbrushand floss.All retainers were in the lower arch only.

Outcomes Survival of retainers was reported.Adverse effects on health were reported in terms of effects on periodontal health and caries. However, thefull data were not available, so statistical analysis was not possible on this particular outcome.Incisor irregularity was reported using Little’s irregularity index. This is an appropriate index for this

13Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 16: Revisión Sistemática Retención

Årtun 1997 (Continued)

study.There was no quality of life assessment.

Notes Contact from authors confirmed that no data were available in addition to that in the published paper

Risk of bias

Item Authors’ judgement Description

Allocation concealment? Yes A - Adequate

SD - standard deviation

Characteristics of excluded studies [ordered by study ID]

Study Reason for exclusion

Ahrens 1981 Study only followed up changes for 30 days - this review only includes those patients followed up for at least3 months

Akkaya 1998 Study investigated different interventions during the treatment phase, not during the retention phase. Therewere no appropriate controls in the retention phase

Akkaya 1999 Study investigated different interventions during the treatment phase, not during the retention phase. Therewere no appropriate controls in the retention phase

Axelsson 1993 Contact with authors confirmed study was retrospective.

Barber 1981 Outcome data were not relevant to this review.

Bergstrom 1973 No orthodontic treatment was undertaken on patients.

Douglass 1990 Outcome data were not relevant to this review.

Forsberg 1991 Although a retention phase was part of the study, there was no comparison of different types of retention

Harradine 1998 Study discusses relapse, but not retention strategies.

Haydar 1992 Insufficient data were available in paper to allow statistical analysis

Keeling 1998 Data reported were from the end of phase one of treatment only - not at the end of full orthodontic treatment

Larsson 1983 Insufficient data to allow analysis according to statistician

14Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 17: Revisión Sistemática Retención

(Continued)

Mossaz-Joëlson 1989 Study investigated different interventions during the treatment phase, not during the retention phase. Therewere no appropriate controls in the retention phase

Odenrick 1991 Outcome data were not relevant to this review.

Owman-Moll 1995 Outcome data were not relevant to this review.

Owman-Moll 1995b Outcome data were not relevant to this review.

Sandikçioglu 1997 Study investigated different interventions during the treatment phase, not during the retention phase. Therewere no appropriate controls in the retention phase

Sims 1976 Study investigated different interventions during the treatment phase, not during the retention phase. Therewere no appropriate controls in the retention phase

Stormann 2002 There were insufficient data in the original publication. The authors were contacted, but were unwilling torelease any further data

Vecere 1983 Author’s thesis was reviewed and this confirmed that the study was retrospective

Wheeler 2002 Data reported is at the end of phase one of treatment only - not at the end of full orthodontic treatment

Wieslander 1984 Study investigated different interventions during the treatment phase, not during the retention phase. Therewere no appropriate controls in the retention phase

Characteristics of ongoing studies [ordered by study ID]

Millett 2004

Trial name or title A multicentre randomised clinical trial of 2 lower arch retainers after active orthodontic treatment

Methods

Participants Patients who have worn upper and lower fixed appliances. Patients treated in a teaching or district generalhospital

Interventions Lower retainer is randomly allocated as either 0.0195“ stainless steel multistrand wire or lower vacuum-formedretainer.Multicentre study.

Outcomes Relapse (measured by Little’s index and PAR). Periodontal and caries status, operator and patient satisfaction.Failure rate of retainer

Starting date 2004.

Contact information Prof Declan Millett, Orthodontic Department, University of Cork

15Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 18: Revisión Sistemática Retención

Millett 2004 (Continued)

Notes

O’Brien 2001

Trial name or title Long-term effects of orthodontic growth modification: study 3 retention

Methods

Participants Patients who have received twin block treatment followed by upper and lower fixed appliances. Originaloverjet greater than 7 mm. Excluding individuals with clefts of lip or palate or both or any other suspectedor identifiable syndrome; people with midline diastema not caused by incisor proclination; people withhypodontia and treatment discontinued early; poor oral hygiene.Patients treated in a district general or teaching hospital.

Interventions Patients randomly allocated to either:upper and lower Essix retainers worn at night only or upper Hawley, lower bonded retainer. The Hawley willbe worn at night only. This is a multicentre study

Outcomes Change in IOTN and PAR scores.

Starting date 2001.

Contact information Prof Kevin O’Brien,Orthodontic Department,School of Dentistry, The University of Manchester,Higher Cambridge Street, Manchester, M15 6FH.

Notes

Williams 2004

Trial name or title A randomised clinical trial to compare the clinical effectiveness ofHawley and vacuum formed retainers in specialist orthodontic practice

Methods

Participants All subjects who are about to have their fixed appliances removed afterthe start of the trial and meet the inclusion criteria will be invitedto participate in the study. The study plans to recruit 400 patientsInclusion criteria:completion of an active phase of orthodontic treatment using full archupper and lower pre-adjusted edgewise fixed appliances.Patients requiring both upper and lower removable retainers.NHS patients.Pre-treatment records available (treatment plan and studymodels).Exclusion criteria:

16Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 19: Revisión Sistemática Retención

Williams 2004 (Continued)

single arch and sectional fixed appliance cases.Patients with cleft lip and palate or other craniofacial syndromes or anomalies.Cases involving rapid maxillary expansion. Patients with hypodontia requiring space maintenance with anartificial tooth. Patients with a history of periodontal disease.Cases requiring a bonded retainer.Early debond (where main objectives of the treatment plan not completed). Transfer cases from an externalsource. Patients with diagnosed learning difficulties

Interventions Patients were randomised to receive upper and lower Hawley retainers orupper and lower vacuum formed retainers.

Outcomes Relapse, survival rate, patient satisfaction, cost effectiveness

Starting date 2003.

Contact information Prof Alison Williams, Dept of Dental Public Health and OHSR, Kings College Dental School, CaldecottRoad, Denmark Hill, London

Notes

17Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 20: Revisión Sistemática Retención

D A T A A N D A N A L Y S E S

Comparison 1. Circumferential supracrestal fiberotomy and removable retainer full time versus removable retainerfull time

Outcome or subgroup titleNo. ofstudies

No. ofparticipants Statistical method Effect size

1 Assessment of stability(maxillary)

1 23 Mean Difference (IV, Fixed, 95% CI) -2.34 [-3.31, -1.37]

2 Assessment of stability(mandibular)

1 23 Mean Difference (IV, Fixed, 95% CI) -2.8 [-3.63, -1.97]

Comparison 2. Thick plain canine-to-canine bonded retainer versus thick spiral canine-to-canine bonded retainer

Outcome or subgroup titleNo. ofstudies

No. ofparticipants Statistical method Effect size

1 Survival of retainers (how manyfailed)

1 24 Risk Ratio (M-H, Fixed, 95% CI) 0.30 [0.04, 2.27]

Comparison 3. Thick plain canine-to-canine bonded retainer versus thin spiral wire bonded to incisors andcanines

Outcome or subgroup titleNo. ofstudies

No. ofparticipants Statistical method Effect size

1 Survival of retainers (how manyfailed)

1 22 Risk Ratio (M-H, Fixed, 95% CI) 0.33 [0.04, 2.73]

Comparison 4. Thick plain canine-to-canine retainer versus removable retainer

Outcome or subgroup titleNo. ofstudies

No. ofparticipants Statistical method Effect size

1 Survival of retainers (how manyfailed)

1 25 Risk Ratio (M-H, Fixed, 95% CI) 0.64 [0.07, 6.14]

18Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 21: Revisión Sistemática Retención

Comparison 5. Thick spiral canine-to-canine bonded retainer versus thin spiral wire bonded to incisors andcanines

Outcome or subgroup titleNo. ofstudies

No. ofparticipants Statistical method Effect size

1 Survival of retainers (how manyfailed)

1 24 Risk Ratio (M-H, Fixed, 95% CI) 1.13 [0.32, 3.99]

Comparison 6. Thick spiral canine-to-canine bonded retainer versus removable

Outcome or subgroup titleNo. ofstudies

No. ofparticipants Statistical method Effect size

1 Survival of retainers 1 27 Risk Ratio (M-H, Fixed, 95% CI) 2.15 [0.47, 9.85]

Comparison 7. Thin spiral wire bonded to incisors and canines versus removable retainers

Outcome or subgroup titleNo. ofstudies

No. ofparticipants Statistical method Effect size

1 Survival of retainers (how manyfailed)

1 25 Risk Ratio (M-H, Fixed, 95% CI) 1.91 [0.38, 9.51]

Comparison 8. Circumferential supracrestal fiberotomy and removable retainers nights only versus removableretainers nights

Outcome or subgroup titleNo. ofstudies

No. ofparticipants Statistical method Effect size

1 Adverse effects on health (changein epithelial attachment after 6months)

1 299 Mean Difference (IV, Fixed, 95% CI) Not estimable

2 Adverse effects on health (changein keratinised gingiva after 6months)

1 299 Mean Difference (IV, Fixed, 95% CI) Not estimable

19Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 22: Revisión Sistemática Retención

Comparison 9. Hawley retainer versus clear overlay retainer

Outcome or subgroup titleNo. ofstudies

No. ofparticipants Statistical method Effect size

1 Assessment of stability (degree ofsettling)

1 30 Mean Difference (IV, Fixed, 95% CI) 6.53 [2.57, 10.49]

Comparison 10. Resin versus multistrand bonded retainers

Outcome or subgroup titleNo. ofstudies

No. ofparticipants Statistical method Effect size

1 Survival rate 1 20 Risk Ratio (M-H, Fixed, 95% CI) 5.0 [0.70, 35.50]

Analysis 1.1. Comparison 1 Circumferential supracrestal fiberotomy and removable retainer full time

versus removable retainer full time, Outcome 1 Assessment of stability (maxillary).

Review: Retention procedures for stabilising tooth position after treatment with orthodontic braces

Comparison: 1 Circumferential supracrestal fiberotomy and removable retainer full time versus removable retainer full time

Outcome: 1 Assessment of stability (maxillary)

Study or subgroup Surgery No surgeryMean

Difference WeightMean

Difference

N Mean(SD) N Mean(SD) IV,Fixed,95% CI IV,Fixed,95% CI

Taner 2000 11 0.16 (0.31) 12 2.5 (1.68) 100.0 % -2.34 [ -3.31, -1.37 ]

Total (95% CI) 11 12 100.0 % -2.34 [ -3.31, -1.37 ]Heterogeneity: not applicable

Test for overall effect: Z = 4.74 (P < 0.00001)

Test for subgroup differences: Not applicable

-10 -5 0 5 10

Favours treatment Favours control

20Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 23: Revisión Sistemática Retención

Analysis 1.2. Comparison 1 Circumferential supracrestal fiberotomy and removable retainer full time

versus removable retainer full time, Outcome 2 Assessment of stability (mandibular).

Review: Retention procedures for stabilising tooth position after treatment with orthodontic braces

Comparison: 1 Circumferential supracrestal fiberotomy and removable retainer full time versus removable retainer full time

Outcome: 2 Assessment of stability (mandibular)

Study or subgroup Surgery No surgeryMean

Difference WeightMean

Difference

N Mean(SD) N Mean(SD) IV,Fixed,95% CI IV,Fixed,95% CI

Taner 2000 11 0.16 (0.36) 12 2.96 (1.41) 100.0 % -2.80 [ -3.63, -1.97 ]

Total (95% CI) 11 12 100.0 % -2.80 [ -3.63, -1.97 ]Heterogeneity: not applicable

Test for overall effect: Z = 6.65 (P < 0.00001)

Test for subgroup differences: Not applicable

-10 -5 0 5 10

Favours treatment Favours control

Analysis 2.1. Comparison 2 Thick plain canine-to-canine bonded retainer versus thick spiral canine-to-

canine bonded retainer, Outcome 1 Survival of retainers (how many failed).

Review: Retention procedures for stabilising tooth position after treatment with orthodontic braces

Comparison: 2 Thick plain canine-to-canine bonded retainer versus thick spiral canine-to-canine bonded retainer

Outcome: 1 Survival of retainers (how many failed)

Study or subgroup Thick plain wire Thick spiral wire Risk Ratio Weight Risk Ratio

n/N n/N M-H,Fixed,95% CI M-H,Fixed,95% CI

rtun 1997 1/11 4/13 100.0 % 0.30 [ 0.04, 2.27 ]

Total (95% CI) 11 13 100.0 % 0.30 [ 0.04, 2.27 ]Total events: 1 (Thick plain wire), 4 (Thick spiral wire)

Heterogeneity: not applicable

Test for overall effect: Z = 1.17 (P = 0.24)

0.1 0.2 0.5 1 2 5 10

Favours treatment Favours control

21Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 24: Revisión Sistemática Retención

Analysis 3.1. Comparison 3 Thick plain canine-to-canine bonded retainer versus thin spiral wire bonded to

incisors and canines, Outcome 1 Survival of retainers (how many failed).

Review: Retention procedures for stabilising tooth position after treatment with orthodontic braces

Comparison: 3 Thick plain canine-to-canine bonded retainer versus thin spiral wire bonded to incisors and canines

Outcome: 1 Survival of retainers (how many failed)

Study or subgroup Thick plain Thin spiral Risk Ratio Weight Risk Ratio

n/N n/N M-H,Fixed,95% CI M-H,Fixed,95% CI

rtun 1997 1/11 3/11 100.0 % 0.33 [ 0.04, 2.73 ]

Total (95% CI) 11 11 100.0 % 0.33 [ 0.04, 2.73 ]Total events: 1 (Thick plain), 3 (Thin spiral)

Heterogeneity: not applicable

Test for overall effect: Z = 1.02 (P = 0.31)

0.1 0.2 0.5 1 2 5 10

Favours treatment Favours control

Analysis 4.1. Comparison 4 Thick plain canine-to-canine retainer versus removable retainer, Outcome 1

Survival of retainers (how many failed).

Review: Retention procedures for stabilising tooth position after treatment with orthodontic braces

Comparison: 4 Thick plain canine-to-canine retainer versus removable retainer

Outcome: 1 Survival of retainers (how many failed)

Study or subgroup Thick plain Removable Risk Ratio Weight Risk Ratio

n/N n/N M-H,Fixed,95% CI M-H,Fixed,95% CI

rtun 1997 1/11 2/14 100.0 % 0.64 [ 0.07, 6.14 ]

Total (95% CI) 11 14 100.0 % 0.64 [ 0.07, 6.14 ]Total events: 1 (Thick plain), 2 (Removable)

Heterogeneity: not applicable

Test for overall effect: Z = 0.39 (P = 0.70)

0.1 0.2 0.5 1 2 5 10

Favours treatment Favours control

22Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 25: Revisión Sistemática Retención

Analysis 5.1. Comparison 5 Thick spiral canine-to-canine bonded retainer versus thin spiral wire bonded to

incisors and canines, Outcome 1 Survival of retainers (how many failed).

Review: Retention procedures for stabilising tooth position after treatment with orthodontic braces

Comparison: 5 Thick spiral canine-to-canine bonded retainer versus thin spiral wire bonded to incisors and canines

Outcome: 1 Survival of retainers (how many failed)

Study or subgroup Canine to canine Incisors and canines Risk Ratio Weight Risk Ratio

n/N n/N M-H,Fixed,95% CI M-H,Fixed,95% CI

rtun 1997 4/13 3/11 100.0 % 1.13 [ 0.32, 3.99 ]

Total (95% CI) 13 11 100.0 % 1.13 [ 0.32, 3.99 ]Total events: 4 (Canine to canine), 3 (Incisors and canines)

Heterogeneity: not applicable

Test for overall effect: Z = 0.19 (P = 0.85)

0.1 0.2 0.5 1 2 5 10

Favours treatment Favours control

Analysis 6.1. Comparison 6 Thick spiral canine-to-canine bonded retainer versus removable, Outcome 1

Survival of retainers.

Review: Retention procedures for stabilising tooth position after treatment with orthodontic braces

Comparison: 6 Thick spiral canine-to-canine bonded retainer versus removable

Outcome: 1 Survival of retainers

Study or subgroup Thick spiral Removable Risk Ratio Weight Risk Ratio

n/N n/N M-H,Fixed,95% CI M-H,Fixed,95% CI

rtun 1997 4/13 2/14 100.0 % 2.15 [ 0.47, 9.85 ]

Total (95% CI) 13 14 100.0 % 2.15 [ 0.47, 9.85 ]Total events: 4 (Thick spiral), 2 (Removable)

Heterogeneity: not applicable

Test for overall effect: Z = 0.99 (P = 0.32)

0.1 0.2 0.5 1 2 5 10

Favours treatment Favours control

23Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 26: Revisión Sistemática Retención

Analysis 7.1. Comparison 7 Thin spiral wire bonded to incisors and canines versus removable retainers,

Outcome 1 Survival of retainers (how many failed).

Review: Retention procedures for stabilising tooth position after treatment with orthodontic braces

Comparison: 7 Thin spiral wire bonded to incisors and canines versus removable retainers

Outcome: 1 Survival of retainers (how many failed)

Study or subgroup Thin spiral Removable Risk Ratio Weight Risk Ratio

n/N n/N M-H,Fixed,95% CI M-H,Fixed,95% CI

rtun 1997 3/11 2/14 100.0 % 1.91 [ 0.38, 9.51 ]

Total (95% CI) 11 14 100.0 % 1.91 [ 0.38, 9.51 ]Total events: 3 (Thin spiral), 2 (Removable)

Heterogeneity: not applicable

Test for overall effect: Z = 0.79 (P = 0.43)

0.1 0.2 0.5 1 2 5 10

Favours treatment Favours control

Analysis 8.1. Comparison 8 Circumferential supracrestal fiberotomy and removable retainers nights only

versus removable retainers nights, Outcome 1 Adverse effects on health (change in epithelial attachment after

6 months).

Review: Retention procedures for stabilising tooth position after treatment with orthodontic braces

Comparison: 8 Circumferential supracrestal fiberotomy and removable retainers nights only versus removable retainers nights

Outcome: 1 Adverse effects on health (change in epithelial attachment after 6 months)

Study or subgroup Surgery No surgeryMean

Difference WeightMean

Difference

N Mean(SD) N Mean(SD) IV,Fixed,95% CI IV,Fixed,95% CI

Edwards 1988 148 0 (0.29) 151 0 (0.31) 100.0 % 0.0 [ -0.07, 0.07 ]

Total (95% CI) 148 151 100.0 % 0.0 [ -0.07, 0.07 ]Heterogeneity: not applicable

Test for overall effect: Z = 0.0 (P = 1.0)

Test for subgroup differences: Not applicable

-10 -5 0 5 10

Favours treatment Favours control

24Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 27: Revisión Sistemática Retención

Analysis 8.2. Comparison 8 Circumferential supracrestal fiberotomy and removable retainers nights only

versus removable retainers nights, Outcome 2 Adverse effects on health (change in keratinised gingiva after 6

months).

Review: Retention procedures for stabilising tooth position after treatment with orthodontic braces

Comparison: 8 Circumferential supracrestal fiberotomy and removable retainers nights only versus removable retainers nights

Outcome: 2 Adverse effects on health (change in keratinised gingiva after 6 months)

Study or subgroup Surgery No surgeryMean

Difference WeightMean

Difference

N Mean(SD) N Mean(SD) IV,Fixed,95% CI IV,Fixed,95% CI

Edwards 1988 148 0 (0.27) 151 0 (0.23) 100.0 % 0.0 [ -0.06, 0.06 ]

Total (95% CI) 148 151 100.0 % 0.0 [ -0.06, 0.06 ]Heterogeneity: not applicable

Test for overall effect: Z = 0.0 (P = 1.0)

Test for subgroup differences: Not applicable

-10 -5 0 5 10

Favours treatment Favours control

Analysis 9.1. Comparison 9 Hawley retainer versus clear overlay retainer, Outcome 1 Assessment of

stability (degree of settling).

Review: Retention procedures for stabilising tooth position after treatment with orthodontic braces

Comparison: 9 Hawley retainer versus clear overlay retainer

Outcome: 1 Assessment of stability (degree of settling)

Study or subgroup Hawley PositionerMean

Difference WeightMean

Difference

N Mean(SD) N Mean(SD) IV,Fixed,95% CI IV,Fixed,95% CI

Sauget 1997 15 11.4 (4.58) 15 4.87 (6.35) 100.0 % 6.53 [ 2.57, 10.49 ]

Total (95% CI) 15 15 100.0 % 6.53 [ 2.57, 10.49 ]Heterogeneity: not applicable

Test for overall effect: Z = 3.23 (P = 0.0012)

Test for subgroup differences: Not applicable

-10 -5 0 5 10

Favours treatment Favours control

25Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 28: Revisión Sistemática Retención

Analysis 10.1. Comparison 10 Resin versus multistrand bonded retainers, Outcome 1 Survival rate.

Review: Retention procedures for stabilising tooth position after treatment with orthodontic braces

Comparison: 10 Resin versus multistrand bonded retainers

Outcome: 1 Survival rate

Study or subgroup Resin modified Multistrand Risk Ratio Weight Risk Ratio

n/N n/N M-H,Fixed,95% CI M-H,Fixed,95% CI

Rose 2002 5/10 1/10 100.0 % 5.00 [ 0.70, 35.50 ]

Total (95% CI) 10 10 100.0 % 5.00 [ 0.70, 35.50 ]Total events: 5 (Resin modified), 1 (Multistrand)

Heterogeneity: not applicable

Test for overall effect: Z = 1.61 (P = 0.11)

0.01 0.1 1 10 100

Favours resin Favours multistrand

A D D I T I O N A L T A B L E S

Table 1. Summary of quality of included studies

Study Concealment Generating ran-dom

Blinding(patients)

Blinding (clini-cian)

Blinding(outcome)

Withdrawal/drop outs

Artun 1997 Adequate (A) Adequate Not possible Not possible Not possible No with-drawals (commu-nication from au-thors)

Edwards 1988 Inadequate (C) Inadequate (al-ternate patients)

Not possible Not possible Possible but notreported

Not fullyreportedand no intention-to-treat analysis

Sauget 1997 Inadequate (C) Inadequate(alternate)

Not possible Not possible Blinding used No withdrawals/drop outs (com-munication fromauthors)

Taner 2000 Inadequate (C) Inadequate(alternate)

Not possible Not possible Blinding used 1 drop out (com-munication fromauthor (not anal-ysed))

26Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 29: Revisión Sistemática Retención

Table 1. Summary of quality of included studies (Continued)

Rose 2002 Adequate (A) Adequate Not possible Not possible Not possible No withdrawals

A P P E N D I C E S

Appendix 1. MEDLINE (OVID) search strategy

Subject search strategy for MEDLINE via OVID(Controlled vocabulary is given in upper case type and free text terms in lower case)1. exp ORTHODONTICS/2. orthodontic$.mp.3. or/1-24. (retention or retain$).mp. [mp=title, abstract, cas registry/ec number word, mesh subject heading]5. (stabilise$ or stabilize$).mp. [mp=title, abstract, cas registry/ec number word, mesh subject heading]6. (fraenectom$ or frenectom$).mp. [mp=title, abstract, cas registry/ec number word, mesh subject heading]7. (fiberotom$ or fibreotom$).mp. [mp=title, abstract, cas registry/ec number word, mesh subject heading]8. ”interproximal stripping“.mp. [mp=title, abstract, cas registry/ec number word, mesh subject heading]9. pericision.mp. [mp=title, abstract, cas registry/ec number word, mesh subject heading]10. reproximat$.mp. [mp=title, abstract, cas registry/ec number word, mesh subject heading]11. ((gingiv$ or periodont$) adj4 surg$).mp. [mp=title, abstract, cas registry/ec number word, mesh subject heading]12. (retain or retention).mp. [mp=title, abstract, cas registry/ec number word, mesh subject heading]13. 11 and 1214. or/4-1015. 13 or 1416. 3 and 15

W H A T ’ S N E W

Last assessed as up-to-date: 10 November 2005.

Date Event Description

19 August 2008 Amended Converted to new review format.

27Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 30: Revisión Sistemática Retención

H I S T O R Y

Protocol first published: Issue 3, 2000

Review first published: Issue 1, 2004

Date Event Description

11 November 2005 New search has been performed This update of the review includes one more study bringing the total numberup to five. The search (May 2005) was conducted 28 months after the initialsearch (January 2003). The results of the review remain unchanged

C O N T R I B U T I O N S O F A U T H O R S

Simon Littlewood (SL), Declan Millett (DM), Bridget Doubleday (BD) and David Bearn (DB) wrote the protocol. All review authorscontributed to writing the review. SL co-ordinated the review and wrote the letters to the authors.

SL, DM, BD and DB independently assessed the eligibility of the trials, extracted data and assessed the quality of the trials. HelenWorthington (HW) assessed the suitability of the data from the trial reports for inclusion, and undertook the statistical analysis.

D E C L A R A T I O N S O F I N T E R E S T

None known.

S O U R C E S O F S U P P O R T

Internal sources

• School of Dentistry, The University of Manchester, UK.• St Luke’s Hospital, Bradford, UK.• Glasgow Dental Hospital, Glasgow, UK.

External sources

• No sources of support supplied

I N D E X T E R M S

28Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.

Page 31: Revisión Sistemática Retención

Medical Subject Headings (MeSH)

∗Orthodontic Retainers; Orthodontics, Corrective [∗methods]; Randomized Controlled Trials as Topic; Tooth Migration [∗prevention& control]

MeSH check words

Humans

29Retention procedures for stabilising tooth position after treatment with orthodontic braces (Review)

Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.