Vertical effects of maxillary molar distalization with clear aligners in Class II patients: A systematic review

Background: Maxillary molar distalization is a common strategy used in non-extraction treatments of Class II malocclusion. However, with conventional orthodontic therapy, the procedure is contraindicated for hyperdivergent subjects due to an increase in vertical dimension. Clear aligners, with digitally planned attachments, offer precise control of teeth movement and could be a viable alternative. This study aims to provide scientific evidence on the efficacy of clear aligners in the stability and control of vertical dentoskeletal dimension, compared to conventional orthodontic therapy. Material and methods: Electronic search from 2014 to July 2024 was conducted on databases: PubMed, The Cochrane Library, EBSCO host, ScienceDirect, and Web of Science. The search was established on a well-defined research question following the PICO principle (population, intervention, comparator, outcome). Assessment of risk of bias was performed for each study based on its type and design. Results: Six studies were included for qualitative analysis, showing overall low to moderate risk of bias. In the clear aligners treatment groups, there was no increase in craniofacial vertical dimension in all patterns. Additionally, a significant reduction in vertical skeletal and occlusal dimensions was observed in normodivergent group. Significant decreases in the linear position of upper molars were found in four studies involving the three vertical patterns. When comparing clear aligners with conventional therapy, less control of divergence was noted, with significant increases in anterior facial height in the conventional treatment group. Conclusion: Clear aligners appear to effectively control and prevents increases in vertical skeletal and dentoalveolar dimensions across all vertical patterns. Registration: PROSPERO CRD42024523177.