Computed tomography evaluation of risk factors for an undesirable buccal split during sagittal split ramus osteotomy

Abstract

Sagittal split ramus osteotomy (SSRO) sometimes induces an irregular split pattern referred to as a bad split. We investigated the risk factors for bad splits in the buccal plate of the ramus during SSRO. Ramus morphology and bad splits in the buccal plate of the ramus were assessed using preoperative and postoperative computed tomography images. Of the 53 rami analyzed, 45 had a successful split, and 8 had a bad split in the buccal plate. Horizontal images at the height of the mandibular foramen showed that there were significant differences in the ratio of the forward thickness to the backward thickness of the ramus between patients with a successful split and those with a bad split. In addition, the distal region of the cortical bone tended to be thicker and the curve of the lateral region of the cortical bone tended to be smaller in the bad split group than in the good split group. These results indicated that a ramus shape in which the width becomes thinner towards the back frequently induces bad splits in the buccal plate of the ramus during SSRO, and more attention should be paid to patients who have rami of these shapes in future surgeries.

Sixty Years of Innovation in Biomechanical Orthognathic Surgery: The State of the Art and Future Directions

“…This advantage may be of particular interest in bone surgery, where a particular geometric design of the osteotomy is required [65]. BSSO sometimes induces an irregular ramus splitting pattern, referred to as a bad split, with results indicating that a ramus shape in which the width becomes thinner posteriorly (shorter ramus and low thickness of the buccolingual alveolar region distal to the second molar) often induces bad splits in the buccal plate of the ramus during surgery [66,67]. A study of bone mineral density and muscle mass in adults with developmental skeletal discrepancies showed that 45.7% of the case group were osteopenic or osteoporotic and had significantly lower muscle mass, increasing the risk of bad splits [68].…”