Effectiveness of orthodontic treatment with functional appliances on maxillary growth in the short term: A systematic review and meta-analysis

Introduction The aim of this systematic review was to evaluate the treatment effects on maxillary growth of removable functional appliances that advance the mandible to a more forward position in patients with Class II malocclusion. Methods Sixteen electronic databases and reference lists of studies were searched up to April 2015. Only randomized clinical trials and prospective controlled clinical trials investigating Class II growing patients treated with removable functional appliances were included. Two authors independently accomplished study selection, data extraction, and risk of bias assessment. All pooled analyses of data were based on random-effects models. Statistical heterogeneity was evaluated. Results In total, 14 studies were included (5 randomized clinical trials, 9 prospective controlled clinical trials) that collected data from 765 patients (405 treated, 360 untreated controls). The mean differences in treatment effect of functional appliances, relative to the untreated controls, were −0.61° per year (95% CI, −0.69° to −0.25°) for SNA angle, −0.61 mm per year (95% CI, −0.90 to −0.32 mm) for anterior maxillary displacement, and +0.07° per year (95% CI, −0.17° to +0.32°) for maxillary plane rotation. Conclusions Removable functional appliances in Class II growing patients have a slight inhibitory effect on the sagittal growth of the maxilla in the short term, but they do not seem to affect rotation of the maxillary plane.