Skeletal and dentoalveolar effects of mandibular advancement with clear aligners in the treatment of skeletal class II: A systematic review and meta-analysis

This study aims to assess the skeletal and dentoalveolar effects of clear aligners in treating skeletal class II malocclusion and compare these effects to those achieved by conventional functional appliances in growing patients. A systematic electronic search was conducted in PubMed, the Cochrane Library, Scopus, Science Direct, and EBSCO HOST databases. The search was based on a defined research question following the Population, Intervention, Comparison, and Outcome principle. Risk of bias was assessed using the Newcastle-Ottawa Scale, and certainty of evidence was evaluated using Grading of Recommendations Assessment, Development, and Evaluation. Random-effects meta-analysis with subgroup analyses by control group type (untreated, Twin-Block, Herbst) were performed. Eight studies met the inclusion criteria, of which six were included in the meta-analysis. When pooling all control groups, no statistically significant differences were found between clear aligners and conventional appliances. However, subgroup analysis revealed that when comparing untreated controls to clear aligner’s significant reduction in A point-Nasion-B angle and an increase in Sella-Nasion-B angle were found. When compared to conventional appliances, clear aligners showed superior lower incisor control compared to Herbst appliances and greater upper molar extrusion. Clear aligners for mandibular advancement produce skeletal effects that exceed natural growth and are comparable to conventional appliances in growing patients. They offer potential advantages in lower incisor control but show a tendency for upper molar extrusion.