Purpose: I will describe the sagittal split ramus osteotomy using the ultrasonic bone cutting device that we have recently begun to use in our institution to prevent inferior alveolar nerve damage and detail the operative procedure, which produces little nerve damage.

Methods and materials: The osteotomy is started from the front edge of the mandibular ramus. When a complete split is made to the posterior edge, a Lindemann bur needs to be used for part of the horizontal osteotomy. It can be achieved with the view of endoscope. In lateral vertical osteotomy, three bone cuts (horizontal, anterior edge, vertical) are made consecutively and we attempt to split the bone with a splitter in order to reliably cut the cortical bone apart to the inferior edge. The location of the shallow nerve is confirmed, and if the splitter can be attached to the proximal bone fragment side, the separation can be accomplished from the bone surface at this stage. The splitter is gradually opened larger, and the final split of the inferior edge is done with a largish osteotome in a portion selected so that the nerve will not be compressed. Bone fragment fixation is done with a single mini plate.

Results: In recent 9 months, we performed 15 cases of SSRO with this presented method. Only one side had shown the slight paresthesia of mental region. The rate of nerve damage was only 3.3%, and it was smaller than one of the case series performed with saw and chisel.

Conflict of interest : None declared.