Coronectomy of the mandibular third molar: a retrospective study of 185 procedures and the decision to repeat the coronectomy in cases of failure.

PURPOSE: A prevalent complication associated with mandibular third molar extraction is inferior alveolar nerve (IAN) injury. This study evaluated the success rate of coronectomy and, in the event of failure of the procedure, retreatment. PATIENTS AND METHODS: One hundred seventy-three patients underwent 185 coronectomy procedures of the mandibular third molar to prevent IAN injury. The coronectomy was performed along the cementoenamel junction. Residual roots were trimmed 3 to 4 mm below the crest margin. No pulp treatment was performed and the roots were left vital. A postoperative orthopantogram was recorded immediately after the procedure or at follow-up 1 month later. Two additional orthopantographic views were taken at 6- and 12-month follow-up appointments. Statistical analyses were performed to assess differences in root migration, pain, wound healing and failure by age, gender, and time elapsed from coronectomy. Statistical data were considered significant at a P value less than .05. RESULTS: Statistical differences in the migration of residual roots from 6 to 12 months were found. Migration of the roots was found in younger patients. In a total of 10 cases of failure, 4 were treated with repeat coronectomy. The other 6 cases were treated with reoperation (ie, removal of residual roots). CONCLUSION: Immediate postoperative radiographic imaging is recommended, as well as, follow-up evaluation 12 months after surgery. In addition, repeat coronectomy is recommended for cases in which enamel retention is diagnosed to prevent residual roots from becoming infected.