Lip Morphology in Patients With Facial Asymmetry Can Be Corrected by 2-Jaw Surgery

Surgical orthodontic patients with facial asymmetry frequently show asymmetry of the lips, and this is often a major complaint of patients. This study investigated whether lip asymmetry associated with the maxilla and mandible was improved when 2-jaw surgery was performed in surgical orthodontic treatment.

Inclusion criteria for this retrospective cohort study were 1) an anteroposterior maxillary relation defined as skeletal Class I; 2) menton (Me) tranverse deviation greater than 5.0 mm; 3) maxillary cant greater than 3.0°; and 4) 2-jaw surgery. Primary predictor variables in this study were skeletal morphologic measurements (Me deviation, maxillary cant, and maxillary distance ratio) before and after treatment. Outcome variables were lip morphology measurements (labial commissure distance, lip angle, and lip area). Additional variables included age and gender. Vertical distances, angles, and area of the upper and lower lips were measured and compared before and after treatment. Hard tissues were measured using posteroanterior cephalograms. Paired t test and correlation coefficients were calculated.

Fourteen patients (4 men [28.5%] and 10 women [71.5%]; mean age, 29 yr) were included. Meaningful changes were observed in distance and angle measurements of the lips from before to after treatment. In area measurement, ratios of the area on the deviated side to that on the contralateral side for the upper and lower lips changed markedly and were close to 1.0 compared with before treatment. A relevant correlation was found between change in Me deviation and change in ratio of the height of the labial commissure.

In cases of facial asymmetry caused by deviation of the maxilla and mandible, lip asymmetry can be adequately corrected by leveling the canted occlusal plane and positioning the Me toward the midline with 2-jaw surgery.