Soft tissue changes of upper lip and nose following posterosuperior rotation of the maxilla by Le Fort I osteotomy

ABSTRACT

INTRODUCTION: This study evaluate the soft tissue changes to the upper lip and nose after Le Fort I maxillary posterosuperior rotational movement. MATERIALS AND METHODS: Twenty Skeletal class III patients, who had undergone bimaxillary surgery with a maxillary Le Fort I osteotomy and bilateral sagittal split ramus osteotomy, were included in the study. The surgical plan for maxilla was posterosuperior rotational movement, with the rotation center in the anterior nasal spine (ANS) of maxilla. Soft and hard tissue changes were measured by evaluating the lateral cephalograms obtained prior to surgery and at least 6 months after surgery. For cephalometric analysis, four hard tissue landmarks ANS, posterior nasal spine [PNS], A point, U1 tip), and five soft tissue landmarks (pronasale [Pn], subnasale [Sn], A' Point, upper lip [UL], stomion superius [StmS]) were marked. A paired t test, Pearson's correlation analysis and linear regression analysis were used to evaluate the soft and hard tissue changes and assess the correlation. A P value <0.05 was considered significant. RESULTS: The U1 tip moved 2.52+/-1.54 mm posteriorly in the horizontal plane (P<0.05). Among the soft tissue landmarks, Pn moved 0.97+/-1.1 mm downward (P<0.05), UL moved 1.98+/-1.58 mm posteriorly (P<0.05) and 1.18+/-1.85 mm inferiorly (P<0.05), and StmS moved 1.68+/-1.48 mm posteriorly (P<0.05) and 1.06+/-1.29 mm inferiorly (P<0.05). The ratios of horizontal soft tissue movement to the hard tissue were 10.47 for the A point and A' point, and 10.74 for the U1 tip and UL. Vertically, the movement ratio between the A point and A' point was 10.38, between U1 tip and UL was 10.83, and between U1 tip and StmS was 10.79. CONCLUSION: Posterosuperior rotational movement of the maxilla in Le Fort I osteotomy results in posterior and inferior movement of UL. In addition, nasolabial angle was increased. Nasal tip and base of the nose showed a tendency to move downward and showed significant horizontal movement. The soft tissue changes in the upper lip and nasal area are believed to be induced by posterior movement at the UL area.