Biomechanical Evaluation of Sagittal Split Ramus Osteotomy Fixation Techniques in Mandibular Setback

The objective of this study was to evaluate and compare the biomechanical behavior of internal fixation techniques in bilateral sagittal split ramus osteotomies (BSSROs) for mandibular setback. Artificial polyurethane mandibles were used in this study. The distal segment of the mandible was repositioned in an 8-mm setback position. All mandibles were divided into three groups: Group 1 had a straight plate with a four-hole monocortical fixation, Group 2 had a curved plate with a four-hole monocortical fixation, and Group 3 had a three-inverted L-type bicortical screw fixation. Vertical loads were applied on the incisal edge by a material testing system. The resistance force at 1, 3, 5, and 10 mm of displacement was analyzed. From the experimental results, Group 1 showed significantly lower results than Groups 2 and 3. No significant difference was observed between Groups 2 and 3 at 1, 3, and 5 mm of displacement. However, at 10 mm of displacement, the resistance force of Group 3 was greater than that of Group 2. For BSSROs, this study concluded that curved plate fixation exhibited the same rigidity as the inverted-L bicortical screw fixation did at <= 5 mm displacement.