Three-dimensional computer-graphic demonstration of facial soft tissue changes in mandibular prognathic patients after mandibular sagittal ramus osteotomy.

The purpose of this study is to demonstrate the three-dimensional changes in facial soft tissues in prognathic patients after orthognathic surgery. The soft tissue and skeletal tissue changes were analyzed with a noncontact three-dimensional digitizing system and roentgenographic cephalometry, respectively. Forty prognathic patients with or without asymmetry, who received only mandibular sagittal ramus osteotomy, were included in the study. The preoperative and 3-month postoperative digitized soft tissue images were superimposed from the nose to the forehead. Changes in the facial soft tissue were illustrated using a computer graphic image with tomographic cross sections at 1-cm intervals. Sagittal soft tissue dislocations of 75 facial measurement points were also calculated. Examination of patients with minimum transverse movement of the mandible revealed significant correlation between soft tissue and related hard tissue dislocation in the sagittal dimension in most landmarks at and below the upper lip. This noncontact three-dimensional digitizing system is very useful in analyzing facial soft tissue changes caused by orthognathic surgery.