Facial soft-tissue changes in skeletal Class III orthognathic surgery patients analyzed with 3-dimensional laser scanning

IntroductionPatients undergoing orthognathic surgery show considerable changes in both hard and soft tissues. The purpose of this study was to use a 3-dimensional (3D) laser scanner to evaluate the soft-tissue changes after the correction of skeletal Class III malocclusions with orthognathic surgery.MethodsThe subjects consisted of 20 Korean patients with skeletal Class III malocclusion who underwent LeFort I osteotomy with maxillary advancement and posterior nasal spine impaction, along with bilateral intraoral vertical ramus osteotomy for mandibular setback. Ten patients (group 1) had 2-jaw surgery with genioplasty, and the other 10 (group 2) had 2-jaw surgery without genioplasty. Three-dimensional images of the patients were acquired with a 3D laser scanner. The ratios of soft-tissue changes to hard-tissue movements were analyzed and compared between the 2 groups. In addition, the changes in the soft-tissue landmarks in the 3D coordinates and the 3D linear, angular, and proportional changes were measured preoperatively and postoperatively, and compared.ResultsThere was no significant difference between the groups in the horizontal ratios of the soft-tissue to hard-tissue changes. In both groups, the ratios of the horizontal changes in the paranasal area were higher than in the subnasale area. There were more changes in the subalar area than in the supracommissural area, and more changes in the chin and labiomental areas than in the subcommissural area. Ala moved anterolaterally, and cheilion moved posteroinferiorly. The distance between upper-lip point and cheilion increased significantly (P <0.05). In the 3D angles, transverse nasal prominence and transverse upper lip prominence increased significantly (P <0.05).ConclusionsThe 3D analysis in this study can be used to estimate the soft-tissue changes in Class III patients who undergo orthognathic surgery.