Survival outcomes of third molar autotransplantation according to impaction severity: a retrospective cohort study

Objectives: Autotransplantation of third molars with complete root formation is a well-established surgical approach for replacing missing teeth, offering biological advantages over conventional prosthetic or implant therapies. The severity of third molar impaction may significantly influence autotransplantation prognosis, yet its clinical significance has not been thoroughly investigated. Materials and Methods: This retrospective cohort analysis assessed for autotransplantation of the third molar. Patients were categorized based on impaction severity, and Kaplan-Meier survival analysis was conducted to estimate cumulative Survival rates. Differences in survival according to impaction severity were assessed using the log-rank test, with further evaluation of associated factors. Results: A total 227 autotransplantation patients (118 males, 109 females, 45.4±14.4 years) and the mean follow-up duration was 26.8 months, achieving an overall 5-year cumulative survival rate of 72.0%. Fully impacted teeth exhibited significantly superior survival outcomes (93.3%) compared to fully erupted (62.9%) and partially impacted teeth (82.9%) (P<0.001). Lower patient age was also significantly associated with better survival (P=0.002). Younger age (≤30 years) was also significantly associated with better survival outcomes (P=0.002). No significant survival differences were found regarding sex, splinting period, extra-socket time, or healing period. Conclusion: Impaction severity is a critical prognostic factor influencing the prognosis of autotransplantation by using the third molars. Comprehensive preoperative evaluation of donor tooth condition, particularly regarding impaction severity, is essential to maximize transplantation outcomes.