Change of lip-line cant after 1-jaw orthognathic surgery in patients with mandibular asymmetry

IntroductionThe purpose of this study was to investigate the change of lip-line cant (LLC) after 1-jaw orthognathic surgery in mandibular asymmetry patients.MethodsPreoperative and postoperative data of 22 patients having 1-jaw orthognathic surgery, with menton deviation over 2° before the surgery, were our subjects. LLC was measured in the preoperative and postoperative frontal photographs, and its change was correlated with various craniofacial measurements obtained from preoperative and postoperative frontal cephalograms and maxillofacial 3-dimensional computed tomography images.ResultsAlthough these subjects had 2.4° of LLC on average before surgery, LLC improved to 0.5° after surgery, and the change (1.9°) was statistically significant. In the correlation analysis, preoperative LLC showed positive correlations with menton deviation and mandibular anterior occlusal plane cant. In the correlation analysis of LLC change, it had positive correlations with preoperative LLC and mandibular anterior occlusal plane cant and preoperative and postoperative change of menton deviation.ConclusionsThese results suggest that LLC is present with chin deviation, even without significant maxillary canting, and can be improved considerably by 1-jaw surgery alone.