Coronectomy: A Useful Approach in Minimizing Nerve Injury Compared With Traditional Extraction of Deeply Impacted Mandibular Third Molars

Abstract

A surgical procedure to minimize the incidence of inferior alveolar nerve injury (IANI) in deeply impacted mandibular third molars (IMTMs) has been proposed. Our study compared the near-term outcomes between coronectomy and traditional extraction of IMTMs and evaluated the long-term complications after coronectomy using cone-beam computed tomography (CBCT). A prospective study was performed of patients with IMTMs at high-risk of IANI using radiographic examination and CBCT. The patients were divided into 2 groups: a coronectomy group and an extraction group. The short-term outcomes, including IANI and other conditions, such as bleeding, pain, and swelling, were assessed in both groups 1week after surgery. The coronectomy patients were evaluated at 3, 6, 12, and 36months after the procedure. The primary long-term complications assessed included root migration, secondary included inflammation, socket healing, and eruption. Relevant factors affecting the outcomes (ie, age, gender, root morphology, impacted depth, impacted angle) were also analyzed. The data were analyzed using SPSS Statistics, version 20.0 (IBM Corp, Armonk, NY). A total of 110 IMTMs (55 in the coronectomy group and 55 in the extraction group) in 92 patients (49 men and 43 women) were included in CBCT assessment. IANI was found in 6 patients in the extraction group and no patient in the coronectomy group (P<.05). After 6months, 2 patients still presented with light numbness. After coronectomy, the roots had migrated quickly during the initial 6months and had become stable1year after surgery; 90.9% of the roots had migrated away from the mandibular nerve canal at 6months postoperatively. No infection had occurred within the 3-year follow-up period. Coronectomy should be considered superior to traditional extraction in the management of the risk of IANI, with few additional complications occurring during follow-up. It could be used as a useful and safe clinical treatment of IMTMs with a high risk of IANI.