Clinical Significance of Computed Tomographic Assessment and Anatomic Features of the Inferior Alveolar Canal as Risk Factors for Injury of the Inferior Alveolar Nerve at Third Molar Surgery

PurposeTo assess the clinical features of the inferior alveolar canal (IAC) using computed tomography (CT) and to analyze the significance of CT examination at third molar surgery.Materials and MethodsA retrospective cohort study was performed involving 99 patients (145 teeth). The relationship between cortication status, buccolingual position, and shape of the IAC on the CT image and inferior alveolar nerve (IAN) injury after third molar surgery were statistically analyzed.ResultsThe shape of the IAC was categorized into 3 groups: round/oval, teardrop, and dumbbell. IAN injury was observed in 7 of 145 cases (4.8%). All 7 cases exhibited absence of cortication; 3 were dumbbell shape and 4 were round/oval. According to logistic regression analysis of cases with absence of cortication, IAC shape was closely related to IAN injury.ConclusionsThese results suggest that assessment of the IAC shape and cortication status at third molar surgery may be clinically useful.