The biological sex lens on early orthopaedic treatment duration and outcomes in Class III orthodontic patients: a systematic review.

BACKGROUND: Treatment outcomes for Class III orthopaedic treatment are highly unpredictable and dependent on the timing of interception, age, and biological sex. OBJECTIVE: This systematic review aimed to assess the effects of sex dimorphism on outcomes and duration of orthopaedic treatment for Class III malocclusion in young children. SEARCH METHODS: Unrestricted search in six electronic databases until May 2021 was conducted. Supplemented by search in resources for published, unpublished literature, and ongoing trials. SELECTION CRITERIA: Randomized and non-randomized controlled trials reporting the use of Class III growth modification appliances, with baseline and outcome data for both sexes, were included. DATA COLLECTION AND ANALYSIS: Study selection and data extraction were performed blindly and in duplicate by two reviewers. ROBINS-I, Cochrane Risk of Bias, and GRADE tools were used for certainty assessment. RESULTS: A total of 2429 records were screened. Four trials fulfilled the inclusion criteria, one was a randomized clinical trial (RCT) comparing facemask and facemask with mini-screw. Two clinical trials evaluated the effects of facemask appliance, one had a control group, another was prospective non-controlled. One compared the effects of the maxillary protraction bow appliance to a no treatment control. Two of the clinical trials were appraised as low and one was appraised as high risk of bias. The overall certainty of the available evidence was assessed as moderate. There was significant clinical heterogeneity in terms of methodology, type of intervention, and the measured outcomes, precluding a meta-analysis. CONCLUSIONS: Minimal variations in sagittal, vertical, and dentoalveolar post-treatment cephalometric changes were reported between sexes. The available evidence is unclear to support these variations. Long-term-powered RCTs assessing cephalometric outcomes between sexes until the end of growth spurt and without pooling are not available, therefore, much needed. REGISTRATION: PROSPERO database number CRD42020185797.