Soft and hard tissue changes after bimaxillary surgery in Chinese Class III patients

Cephalometric studies have shown that the Chinese race tends to have a greater preponderance of skeletal Class III malocclusion. It has also been reported that the soft tissue response to hard tissue movement varies among racial types. The aims of this retrospective cephalometric study were to assess the results of bimaxillary surgery on Chinese subjects presenting with Class III malocclusions and to evaluate the correlation between soft and hard tissue change. The sample consisted of 34 Chinese patients treated with bilateral sagittal split osteotomy and Le Fort I advancement. Lateral cephalograms were taken immediately before surgery and at least six months after surgery. Soft and hard tissue changes were recorded by computer-supported measurements of presurgical and postsurgical lateral cephalograms. Linear regression procedures were used to assess the degree of correlation in terms of soft to hard tissue changes between the two cephalograms. The results showed that there was normalization of the cephalometric variables after surgery. Mandibular soft and hard tissue movements showed a strong correlation in the horizontal direction and a moderate correlation in the vertical direction. Maxillary soft and hard tissue movement showed a moderate to weak correlation in both the horizontal and vertical directions. The ratios of soft to hard tissue movements derived from this study would contribute to the database for planning prediction.