Compliance with removable orthodontic appliances and adjuncts: A systematic review and meta-analysis

•Suboptimal compliance is typical with all types of orthodontic appliances. •Actual wear time is approximately 5 hours per day less than stipulated. •Overreporting of appliance wear was found with all types of appliances. •Factors influencing compliance levels are not fully understood. Introduction The primary aims of this systematic review were to assess objective levels of wear of removable orthodontic appliances and components vs both stipulated and self-reported levels. We also aimed to consider patient experiences and the effectiveness of interventions geared at enhancing compliance. Methods Electronic databases and reference lists of relevant studies were searched with no language restriction (PROSPERO: CRD42016036059). Randomized and nonrandomized controlled trials, prospective cohort studies, case series, qualitative and mixed-methods studies objectively assessing compliance levels were identified. The quality of the studies was assessed using the Cochrane Collaboration's risk of bias tool, risk of bias in non-randomized studies of interventions (ROBINS-I), or mixed-methods appraisal tool based on their design. Results Of 4269 records, 80 full texts were obtained, with 24 studies meeting the selection criteria. Of these, 11 were included in the quantitative synthesis. A weighted estimate of objectively assessed compliance levels in relation to stipulated wear time was calculated with the discrepancy highest in the headgear group (5.81 hours per day, 95% confidence interval, 4.98, 6.64) based on 6 studies. The mean discrepancy between self-reported and objectively assessed headgear wear was 5.02 hours per day (95% confidence interval, 3.64, 6.40). Compliance level was not directly related to appliance type (P = 0.211). Thematic synthesis was not undertaken because of the limited number of qualitative studies. Conclusions Compliance with removable orthodontic appliances and adjuncts is suboptimal, and patients routinely overestimate duration of wear. Techniques for improving compliance have promise but require further evaluation in high-level research.