The Impact of Extraction Orthodontic Treatment on the Impaction of Mandibular Third Molars: An Imaging-Based Retrospective Cohort Study.

Introduction: This study aimed to evaluate the impact of orthodontic extraction treatment on mandibular third molar impaction by measuring changes in angulation before and after treatment in patients receiving extraction versus non-extraction orthodontic therapy.

Methods: A retrospective analysis was conducted on 30 patients who completed fixed orthodontic treatment at the Department of Stomatology, Deyang People's Hospital, between 2018 and 2023. Patients were divided into two groups, with 15 included in the extraction group and 15 in the nonextraction group. Pre- and post-treatment orthopantomograms (OPGs) were analyzed, with each mandibular third molar quadrant considered an independent sample. Changes in the α-angle of mandibular third molars were compared between the groups.

Results: The mean change in α-angle was -2.42° ± 8.32° in the non-extraction group and 4.85° ± 9.53° in the extraction group, with a statistically significant difference between the two groups (p < 0.05).

Discussion: Whether orthodontic extraction treatment facilitates third molar eruption remains a topic of ongoing debate. Differences in conclusions across studies may be attributed to variations in sample selection, patient age, growth stage, anchorage strategies, and imaging methodology. Our study design attempted to control for these variables by matching participants by age, sex, and treatment duration, and by ensuring comparable baseline α-angle in both groups to minimize confounding. Further prospective studies based on three-dimensional imaging are still needed in the future to validate our conclusions.

Conclusion: Orthodontic treatment involving premolar extraction significantly improved the angulation of mandibular third molars compared to non-extraction treatment, potentially reducing impaction severity and enhancing eruption potential.