Neurosensory Compromising Proximity of Mandibular Canal in Sagittal Split Osteotomy

Objectives: Neurosensory disturbance after sagittal split osteotomy is a common complication. The aim of this study is to evaluate the course of the mandibular canal with the use of computed tomography scan, assess the risk of injury to IAN in classical sagittal split osteotomy technique based on the proximity of mandibular canal to the external cortical bone. Methods: The computer tomography data of 102 mandibular rami were evaluated in respect of the course of the mandibular canal at 3 positions. At each position, the distance between the mandibular canal and the inner surface of the cortical bone were measured and registered as a possible neurosensory compromising proximity if it was less than 1mm or if the mandibular canal came into contact with the external cortical bone. The course of each mandibular canal was allocated to either a neurosensory risk or a non-neurosensory risk group. Results: The mandibular canal was mostly in contact with or within 1mm of proximity to the lingual cortex in all the positions along its course. About 60% of mandibular canals were in the neurosensory risk group if the sagittal split ramus osteotomy were to be performed. Conclusions: The present study showed that neurosensory compromising proximity of the mandibular canal was observed in about 60% of SSRO sites examined. Therefore, alternative procedures to SSRO may need to be devised depending on the site at which the inferior alveolar nerve may be at risk.