The effectiveness of adjuncts or alternatives to the use of orthodontic retainers in preserving posttreatment outcomes: A systematic review.

Introduction: The objective of this study was to systematically evaluate the efficacy of adjuncts or alternatives to mechanical retention in preserving postorthodontic treatment outcomes.

Methods: Electronic databases, unpublished literature, and ongoing trials were searched until July 22, 2022 (PROSPERO CRD42021291165). Randomized and nonrandomized controlled trials investigating the efficacy of adjuncts and alternatives to conventional orthodontic retainers were included. Stability, periodontal effects, cost-effectiveness, and patient-reported outcomes were to be evaluated. The Cochrane Risk of Bias Tool and Risk of Bias In Nonrandomized Studies of Interventions (ROBINS-I) were used for risk of bias assessment. The certainty of the evidence was appraised using the Grading of Recommendations Assessment, Development, and Evaluation system. Exploratory sensitivity analysis was undertaken to calculate the weighted treatment effects of the intervention.

Results: A total of 5128 records were screened. Seven trials fulfilled the inclusion criteria, of which 5 were randomized controlled trials. Five trials were judged to be at high risk of bias, with 2 studies of unclear risk of bias. Heterogeneity between the limited number of included studies precluded the conduct of meta-analysis. Circumferential supracrestal fibrotomy resulted in less increase in the mandibular Little's Irregularity Index (mean difference, -2.30 mm; 95% confidence interval, -2.86 to -1.74). The overall level of evidence was of very low quality.

Conclusions: Adjuncts and alternatives to mechanical retention have promise, but based on the existing evidence, the reliance on mechanical retention cannot be reduced. There is weak evidence supporting circumferential supracrestal fibrotomy to improve stability outcomes. Further high-quality prospective research focusing on the predictability and acceptability of these approaches is needed.