Objective: To evaluate the effectiveness of different retention strategies used to maintain tooth position after treatment by orthodontic appliances.
Data sources: The search strategy was carried out according to the standard Cochrane systematic review methodology. The following databases were searched for randomized clinical trials (RCT) or controlled clinical trials (CCT): Cochrane Oral Health Group Trials Register, Cochrane Clinical Trials Register, MEDLINE and EMBASE. No language restrictions were applied. Authors of trials were contacted to identify unpublished trials. Inclusion and exclusion criteria were applied when considering the studies to be included and a quality assessment made for each paper.
Data selection: The primary outcome was the amount of relapse. Secondary outcomes were survival of retainers, adverse effects on oral health and patient satisfaction.
Data extraction: Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were conducted in duplicate and independently by two reviewers. Five studies (2 RCTs and 3 CCTs) fulfilled the inclusion criteria.
Data synthesis: There was evidence, based on data from one trial, that there was a statistically significant increase in stability in both the mandibular (P<0.001) and maxillary anterior segments (P<0.001) when the CSF (circumferential supracrestal fiberotomy) was used in conjunction with a Hawley retainer, compared with a Hawley retainer alone. However, this evidence may be unreliable due to flaws in the study design. There was also weak, unreliable evidence that teeth settle quicker with a Hawley retainer than with a clear overlay retainer after 3 months.
Conclusions: There is currently insufficient evidence on which to base the clinical practice of orthodontic retention.