Pre-treatment associated factors for open gingival embrasures of upper incisors after maxillary molar distalization with clear aligners: a retrospective study

OBJECTIVE: This retrospective clinical study aims to evaluate the clinical incidence of open gingival embrasures (OGEs) in the anterior maxillary region following sequential distal movement of the maxillary dentition with clear aligner therapy. It also investigates associated factors for OGE to provide a theoretical basis for establishing a preoperative risk assessment system for orthodontic treatment. METHODS: This retrospective study included 75 patients in the permanent dentition stage who underwent sequential maxillary molar distalization (2-4 mm per side) with clear aligners and had complete pre- and post-treatment records. Patients were divided into non-OGE and OGE groups based on post-treatment interdental papilla filling. Intergroup comparisons were performed using the Chi-square test, independent-samples t-test, Welch's t-test, or Mann-Whitney U test as appropriate. Univariate and multivariate logistic regression analyses were used to identify associated factors, with odds ratios (ORs) and 95% confidence intervals (95% CIs) reported. RESULTS: A total of 75 patients (mean age, 25.32 ± 9.44 years) were enrolled from an initial cohort of 630. An incidence of 17.3% for OGE was observed following sequential distal movement of the maxillary dentition using clear aligners. A significant difference in age was found between the non-OGE and OGE groups (P < 0.05). Furthermore, regression analysis demonstrated that age, anteroposterior overlap, ANB angle, and U1-NA angle were statistically associated with OGE (P < 0.05). CONCLUSION: The results indicate an incidence of 17.3% for OGEs in patients undergoing sequential maxillary molar distalization with clear aligners. Age, anteroposterior overlap, ANB angle, and U1-NA angle were found to be significantly associated with OGE occurrence.