Skeletal stability after mandibular setback surgery: comparison between the hybrid technique for fixation and the conventional plate fixation using an absorbable plate and screws.

PURPOSE: The purpose of this study was to compare the temporal changes in condylar long axis and skeletal stability after sagittal split ramus osteotomy (SSRO) with the hybrid fixation technique and the conventional plate fixation.

PATIENTS AND METHODS: Of 44 Japanese patients diagnosed with mandibular prognathism, 22 underwent SSRO with the conventional plate fixation (1 u-HA/PLLA plate and 4 monocortical screws in each side) and 22 underwent SSRO with a hybrid fixation technique (1 u-HA/PLLA plate and 4 monocortical screws and bicortical screw in each side). The temporal changes in condylar long axis and skeletal stability were assessed by axial, frontal, and lateral cephalograms. After surgery, breakage of the plate and screws was checked by 3-dimensional computed tomography (3DCT).

RESULTS: Although there was a significant difference between the groups regarding Me-Ag in T1 (P = 0.0138), there were no significant differences between the groups for the other measurements in lateral, frontal and axial cephalometric analysis in each time interval. In two cases, 4 sides in the conventional plate fixation group, failure of the absorbable plate was found by 3DCT. However, there was no breakage in the hybrid fixation group.

CONCLUSION: This study suggested that there were no significant differences in the postoperative temporal changes between the two groups in mandibular setback surgery.