Mandibular canal and bilateral sagittal split osteotomy: a topographic analysis

Abstract

Background: The mandibular canal ratio analysis with the design of the bilateral sagittal split osteotomy of the mandible can provide important information to enable the professional to set standards and osteotomy levels for each type of malocclusion. Objectives: To analyse the topography of the mandibular canal of a sample of patients undergoing orthognathic surgery using cone-beam computed tomography (CBCT). Methods: 213 CBCT of patients in the preoperative phase who underwent orthognathic surgery were analysed. Points in mandibular foramen, anterior border of the mandible, distal second molar and interproximal first and second lower molars served as reference to perform the measurements in software Dolphin Imaging 3D®. Findings: Patients class III had bilateral reduction in bone height in the regions of anterior border of the mandibular branch, distal second molar and between the molars. Also had bilateral reduced bone thickness in the anterior border of the mandibular ramus. Class II patients showed increased thickness of the base jaw. As the distance of the second molar in relation to the mandibular lingula, class II patients had lower height, and class III patients had greater height. Conclusion: The mandibular canal showed topographical differences between the types of malocclusion, suggesting the need to differentiate the depth and the thickness of the bone cuts.