• Izumi Yoshioka, Tatsurou Tanaka, Amit Khanal, Manabu Habu, Shinji Kito, Masaaki Kodama, Masafumi Oda, Nao Wakasugi-Sato, Shinobu Matsumoto-Takeda, Yasuhiro Fukai, Takatoshi Tokitsu, Megumi Tomikawa, Yuji Seta, Kazuhiro Tominaga, and Yasuhiro Morimoto.
• Department of Oral and Maxillofacial Surgery, Kyushu Dental College, Kokurakita-ku, Kitakyushu, Japan.
• J. Oral Maxillofac. Surg. 2010 Dec 1; 68 (12): 3022-7.

PurposeTo elucidate the relationship between the anatomic position of the inferior alveolar nerve (IAN) at the mandibular second molar and the occurrence of neurosensory disturbances of the IAN after sagittal split ramus osteotomy (SSRO) in patients with mandibular prognathism. Also, the present study evaluated the difference in anatomic position of the IAN between patients with and without mandibular prognathism.Patients And MethodsComputed tomography images were taken of 28 patients with mandibular prognathism and 30 without prognathism. On these scans, the IANs from the mandibular second molar region to the mandibular foramen in the mandibular ramus were identified. The present study was designed as a cross-sectional study. The distance from the buccal aspect of the IAN canal to the outer buccal cortical margin of the mandible in the mandibular second molar regions was measured on the computed tomography images. Also, the linear distance between the superior aspect of the IAN canal and the alveolar crest in these regions was calculated. In addition, we investigated the presence or absence of contact between the IAN canal and the inner buccal cortical margin of the mandible from the mandibular second molar to the mandibular foramen in the mandibular ramus. Next, we examined whether neurosensory disturbances occurring after SSRO were related to the position of the IAN at the mandibular second molar.ResultsA significant difference was found in the occurrence of neurosensory disturbances of the IAN after SSRO between men and women (χ(2) test, P < .05). For the distance from the buccal aspect of the IAN canal to the outer buccal cortical margin of the mandible in the mandibular second molar region, a significant difference was found between groups with and without neurosensory disturbances (Student's t test, P < .01). The shorter the distance from the buccal aspect of the IAN canal to the outer buccal cortical margin, the more frequent the occurrence of neurosensory disturbances of the IAN.ConclusionsThe present results have demonstrated that gender and the anatomic position of the IAN canal at the mandibular second molar are significantly related to the occurrence of neurosensory disturbances of the IAN after SSRO. Therefore, surgeons should clearly inform patients of the increased possibility of neurosensory disturbances after SSRO when the patients are female and are found to have a shorter distance from the buccal aspect of the IAN canal to the outer buccal cortical margin.Copyright © 2010 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

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