Three-dimensional measurements of soft-to-hard tissues before and after bimaxillary surgery in Class III malocclusion patients

PURPOSE:To assess the results of bimaxillary surgery on patients with skeletal Class Ⅲ malocclusions and evaluate the correlation between soft and hard tissue changes.METHODS:The sample consisted of 41 patients treated with bilateral sagittal split osteotomy and Le Fort I advancement.Three dimensional CT reconstruction and measurement were taken immediately before surgery and at least six months after surgery.Pearson linear regression in SPSS11.0 software package was used to access the degree of correlation in terms of soft to hard tissue changes.RESULTS:The results showed that there was normalization of the measurement variables after surgery.Mandibular soft and hard tissue movements showed a strong correlation(r0.9)in the horizontal direction and a moderate correlation(0.82r0.63)in the vertical direction,while the maxillary soft and hard tissue movements showed a moderate(0.78r0.56)to weak(r0.6) correlation in both the horizontal and vertical directions.CONCLUSIONS:The ratios of maxillary soft-to-hard tissue movement were generally lower than that of the mandibular movement in both horizontal and vertical directions.The ratios of soft to hard tissue movements derived from this study would contribute to the database for planning prediction.