The use of inter-maxillary fixation (IMF) screw for mandibular setback surgery

Purpose: The purpose of this study was to assess skeletal stability after mandibular setback surgery with and without an inter-maxillary fixation (IMF) screw. Subjects and Methods: The subjects consisted of 40 patients with mandibular prognathism. The subjects underwent sagittal split ramus osteotomy (SSRO) with titanium plate fixation and were divided into two groups, one with and one without an IMF screw. A lateral cephalogram was done preoperatively, immediately after surgery, and 1 month, 3 months and 6 months postoperatively. The two groups were then compared statistically. Results: In the comparison of the time-course change between the two groups with repeated measure ANOVA, there were significant differences in occlusal plane (between subjects, F=2.517; df=4; P=0.0437) and convexity (between subjects, F=4.048; df=4; P=0.0038). However, there was no significant difference in the other measurements. Conclusion: This study suggested that in most measurements, there was no significant difference between two groups with and without IMF screw in time-course skeletal change. However, use of IMF screw was helpful for orthognathic surgery as a rigid anchor of IMF.