What Is a Safe Distance for Preservation of the Inferior Alveolar Nerve in Lower Gingival Squamous Cell Carcinoma? A Radiographic and Histopathological Study

Purpose: Involvement of the inferior alveolar nerve (IAN) is important in the prognosis and treatment of gingival squamous cell carcinoma (SCC). Methods: In this cross sectional study, patients with gingival SCC (T4a), undergoing hemimandibulectomy or subtotal hemimandibulectomy, were examined. The distance between the lesion and inferior alveolar canal (IAC) was measured, using axial computed tomography scans before resection. Following that, histopathological evaluation of IAN was conducted. The receiver operating characteristic curve was plotted to determine the association of IAN involvement in histopathological evaluation with various distances between the lesion and IAC. Results: A total of 29 patients were examined in this study. The mean distance between the lesion and IAC was 9.40 ± 2.21 mm. Nerve involvement was documented in 9 (45%) out of 20 males, while 11 (55%) men showed no involvement. Thirteen (44.82%) patients showed IAN involvement. The receiver operating characteristic curve demonstrated a cut-off point of 9.75 mm for the lesion-IAN distance. The possibility of IAN involvement was 23.33 times higher in patients who reported paresthesia, compared with patients without nerve involvement (odds ratio, 23.33; 95% CL; P = 0.001) Conclusion: It seems that in a CT scan view, a 9.75-mm safe margin is associated with high accuracy for preserving IAN in patients with gingival SCC. Also, neurosensory disturbance can be considered a strong predictor of IAN involvement. Address correspondence and reprint requests to Reza Tabrizi, DMD, OMFS Department, Shahid Beheshti Dental School, Velenjak, Tehran 30345, Iran; E-mail: tabmed@gmail.com Received 28 September, 2018 Accepted 23 November, 2018 The authors report no conflicts of interest. © 2019 by Mutaz B. Habal, MD.

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