Residual enamel removal to improve outcomes of mandibular third molar coronectomy: A single-center retrospective cohort study

This study aimed to analyze post-coronectomy complications, chronological root survival rate (success rate) using Kaplan–Meier analysis, and postoperative radiographic signs for root extraction. A total of 555 mandibular third molar coronectomies were clinically and radiologically evaluated (mean follow-up period, 27.2 months; range, 1 month to 10.5 years). Complications were observed in 22 (4.0%) cases. Temporary inferior alveolar nerve damage was observed in one (0.2%) case, and 21 (3.8%) retained roots required extraction between 1 and 64 months after coronectomy due to dry socket (two cases, 0.4%), primary non-wound closure (10 cases, 1.8%), secondary root exposure (seven cases, 1.3%), and submucosal root eruption (two cases, 0.4%). Residual enamel after coronectomy was more significantly found on 13 (61.9%) of 21 extracted roots than on 30 (5.6%) of 534 surviving roots. Kaplan–Meier analysis revealed an overall survival rate of 93.8% at 5 years and 92.2% at 10 years. The 5-year survival rates differed significantly (p < 0.001) between the enamel-free (97.0%) and residual enamel-attached (58.3%) roots. The Cox proportional hazards model showed a hazard ratio of 20.87 (95% confidence interval, 8.58–50.72). The long-term outcomes of coronectomy were satisfactory, and a higher success rate is expected when the enamel is completely removed during coronectomy.