Modified hybrid fixation using absorbable plate and screw for mandibular advancement surgery.

PURPOSE: The purpose of this study was to examine the skeletal stability of mandibular advancement after sagittal split ramus osteotomy (SSRO) with modified hybrid fixation using absorbable plates and screws. MATERIALS AND METHODS: A total of 54 Japanese patients were enrolled in this study. Of them, 23 who were diagnosed with mandibular prognathism underwent setback surgery with bi-cortical plate fixation using absorbable plates and screws (setback group). Another 23 who were diagnosed with mandibular retrognathism underwent advancement surgery with modified hybrid fixation using absorbable plates (advance group), and 8 who were diagnosed with mandibular retrognathism underwent advancement surgery with titanium plates (titanium group). Skeletal stability and horizontal condylar angle were analyzed by axial, frontal, and lateral cephalograms preoperatively and at 1 month, 3 months and 1 year post-operatively. The findings were compared statistically. RESULTS: The advance group showed no significant difference compared with the titanium group. There were significant differences between the setback and advance groups regarding SNB, ANB, gonial angle, ramus inclination, occlusal plane, convexity and Me-Ag right in T1 naturally (P < 0.05). However, in T2, there were no significant differences between the groups for the other measurements, although there were significant differences in ANB, interincisal angle, occlusal plane and Me-Ag right (P < 0.05). In T3, a significant difference was seen only in Me-Ag right (P = 0.0145). CONCLUSION: This study suggested that the use of an absorbable plate and screw was useful and reliable for mandibular advancement surgery as well as mandibular setback surgery, when the fixation method was devised successfully.