Coronectomy: a technique to protect the inferior alveolar nerve.

PURPOSE Damage to the inferior alveolar nerve when extracting lower third molars is often caused by the intimate relationship between the nerve and the roots of the teeth. The technique of coronectomy, or intentional root retention, may minimize this problem. PATIENTS AND METHODS Forty-one patients underwent coronectomy on 50 lower third molars with follow-up of at least 6 months. The technique of coronectomy deliberately protected the lingual nerve as part of the surgical procedure. All roots were left at least 3 mm below the buccal and lingual plates of bone. All patients were radiographed preoperatively, immediately postoperatively, and after 6 months. RESULTS There were no cases of inferior alveolar nerve-involved damage in this study of 41 patients who underwent 50 coronectomies. There was 1 case of transient lingual nerve involvement, probably from the use of the lingual retractor. One patient required subsequent removal of the roots of both lower third molars because of failure to heal, and 1 patient required subsequent removal of a root because of subsequent migration to the surface. Root migration was noted in approximately 30% of patients over a 6 month period. CONCLUSION Coronectomy appears to be a viable technique in those cases where removal of the whole tooth might put the inferior alveolar nerve at considerable risk of damage. The technique appears to be associated with a low incidence of complications, but subsequent migration of the roots may be an issue in the long term.