Abstract:

Objective To evaluate the effect of extraction and non-extraction decompensation to bimaxillary orthognathic surgery in skeletal class Ⅲ malocclusion and the effect on postoperative. Methods Records of 36 completed surgical-orthodontic treatment skeletal class Ⅲ malocclusion patients were obtained from School of Stomatology, China Medical University, 18 underwent maxillary premolar extraction, the other 18 underwent non-extraction. Their postdecompensation and postsurgery cephalometric radiographs were analyzed objectively, and their profile scissors-shadows in different groups were evaluated subjectively. Results The cephalometric index of post -presurgical orthodontics showed that there were significant deviations between the extraction and non-extraction groups including U1-SN, Overjet and Cm-Sn-UL values（P<0.05）. During surgery, mandible was retruded（8.66±1.42）mm in extraction group compared with（6.21±3.06）mm in non-extraction group（P<0.05）. After surgery, the extraction group achieved more normal ANB, U1-SN, NA-PA values（P>0.05）. Conclusion Maxillary premolar extraction can make incisor decompensation more complete so that mandible can be retruded to more ideal position and concave face can be successfully corrected.