The study of soft tissue changes of upper and lower lips following bssro in skeletal class iii malocclusion patients

ABSTRACT

PURPOSE: The prediction of profile change as a result of orthognathic surgery remains a problem during preoperative planning because of the difference relative movements of the hard and soft tissues. This study was performed to predict the changes of upper and lower lips after BSSRO with non-rigid fixation. MATERIAL AND METHODS: 15 patients with skeletal Class III malocclusion treated by bilateral sagittal split ramus osteotomy(BSSRO) and mandibular setback were selected for analysis. Cephalometric data of presurgery and postsurgery 12 months were used. Wilcoxon signed rank test, calculation of Spearmans correlation rho and simple regression analysis were performed to predict the relations between hard tissue changes and soft tissue changes. RESULTS: The horizontal change of hard tissue Pogonion and those of lower lips showed high correlation and the ratios were from 71% to 84%. The horizontal change of hard tissue Pogonion and those of chin showed high correlation and the ratios were from 90% to 92%. The horizontal change of hard tissue Pogonion and those of upper lips showed moderate correlation and the ratios were from 7% to 18%. CONCLUSION: This study suggests that the changes of lower lips are highly affected by the hard tissue change of mandible and those of upper lips are moderately affected. In comparison with other studies, no significant differences were found among the fixation methods.