Smile Asymmetry in Patients treated with combined Orthodontics and Orthognathic Surgery

Abstract

AIM: The aim of this study was to examine the relationship between lip canting and the extent of a smile, both pre- and post-operatively, in patients who were treated with combined orthodontics and orthognathic surgery. 
METHODS: This study included 90 clinical photographs of 45 patients smiling, both before and after orthognathic surgery. Facial landmark points were traced to compare pre- and post-operative photographs. The data were used to measure the vertical distance of the lips when smiling – lip elevation and the extent of a smile, both before and after surgery. The correlations among canting, the type of surgery, and Angle class were evaluated by a one-way analysis of variance (ANOVA) and multiple comparisons using the Tamhane post hoc test. 
RESULTS: The magnitude of the post-operative extent of a smile was not significantly correlated with lip elevation and changes in lip canting. There were no statistical differences for Angle class I and asymmetric cases, in contrast to Class II and III results regarding the extent of a smile post-operatively. Bimaxillary surgery resulted in significantly broader smiles, and bilateral sagittal split osteotomy resulted in higher lip elevation post-operatively, though not to a significant extent. 
CONCLUSION: Soft tissues, particularly the smiling lip line, are affected by orthognathic surgery and skeletal malocclusion. However, further studies will be needed to better assess and study smile dynamics.