Position of the mandibular canal.

Because of its numerous advantages, sagittal split osteotomy of the ramus has become the method of choice during the past 30 years. Operative injury to the vascular and nerve bundle within the mandibular canal represents a main risk factor. X-ray studies have been carried out on dry bone material to determine position of the canal. On the basis of the results, the variety of its position was ranked into 4 groups. The risk factor of, and the operative contraindication for, splitting technique in groups 3 and 4 have been emphasized.