Root Migration After Coronectomy of a Mandibular Third Molar With the Inferior Alveolar Nerve Passing Between the Roots: A Case Report.

Extraction of mandibular third molars (MTMs) is one of the most common procedures in oral and maxillofacial surgery. It carries a risk of inferior alveolar nerve (IAN) injury, which may result in altered or lost sensation of the lower lip, chin, teeth, and gingiva. Coronectomy, a surgical technique in which the crown is removed while the vital roots are retained, has been proposed to reduce this risk in cases with close root-nerve proximity. We report the case of a 41-year-old female patient in whom cone beam computed tomography (CBCT) revealed the IAN coursing between the roots of an MTM. Coronectomy was performed to preserve nerve integrity. Follow-up CBCT demonstrated significant migration of the retained root complex within 6-12 months, increasing the distance from the IAN. Five years later, infection associated with the retained roots required surgical root removal. Owing to the favorable migration of the root complex, extraction was completed without IAN injury. This case illustrates that, despite the possibility of late complications requiring reintervention, coronectomy may facilitate root migration away from the nerve and allow safer delayed root removal in anatomically high-risk situations. Careful patient selection, meticulous surgical technique, and long-term radiographic follow-up are essential. Further high-quality long-term studies are needed to standardize coronectomy protocols, evaluate complications, and assess cost-effectiveness compared with conventional extraction.