Impact of Molar Teeth Distalization by Clear Aligners on the Temporomandibular Joint: Systematic Review and...

Background: This review aimed to assess the association between upper molar distalization using clear aligners (CAs) and structural changes in the temporomandibular joint (TMJ). Methods: On February 20, 2025, the following databases were searched: PubMed, Embase, BASE, Web of Science, and Scopus. Studies were included if they reported on orthodontic treatment with CAs involving upper molar distalization and presented TMJ parameter measurements before and after treatment. The JBI Critical Appraisal Checklist for Quasi-Experimental Studies was used to assess the risk of bias. The collected data were analyzed using the paired t-test, mean difference assessment, and Spearman correlation matrix. Results: A total of 4 articles out of 238 records retrieved were included in the review. The mean age of patients was 23.18-29.80 years, and the treatment duration was 1.90-2.21 years. The most important changes were in the posterior and superior joint spaces (PJS and SJS) (p < 0.05), with SJS increasing in two studies (0.56 and 0.7 mm) and PJS increasing in one and decreasing in another (-0.94 and 0.36 mm). Conclusions: Limited evidence suggests that molar distalization with CAs may influence TMJ dimensions to a small extent. However, the results are inconsistent and require further validation with high-quality studies to draw firm conclusions. Registration: The review was pre-registered using the OpenScience Framework (OSF) on 17 April 2025-osf.io/9xyr8. No funding or conflicts of interest were reported.