Assessing the Influence of Chin Asymmetry on Perceived Facial Esthetics With 3-Dimensional Images

Abstract

We used 3-dimensinonal (3D) images to assess the influence of chin asymmetry on perceived facial esthetics, investigate the cognitive boundaries of chin asymmetry among orthodontists, general dentists, and laypersons, and provide quantitative reference for clinical treatment. A 3D facial image was obtained using the 3dMD imaging system (3dMD, Atlanta, GA). The chin was altered in 2-mm increments from 0 to 12mm and to the left and right using the software program. These images were rated by 66 orthodontists, 89 general dentists, and 66 laypersons as 1) chin symmetry; 2) slight chin asymmetry but acceptable; and 3) serious asymmetry and treatment needed. Multivariate mixed linear regression and multivariate mixed logistic regression analyses were used for statistical data analysis. Descriptive and bivariate statistics were calculated, and statistical significance was considered present at P=.05. The observers progressively increased the grade ratings and the desire for surgery for greater asymmetries (P<.001). Orthodontists and general dentists could perceive a chin deviation of 4mm to the right and 2mm to the left, with 8-mm deviation considered to require treatment. Laypersons had a clear perception of a 4-mm chin deviation, with 8mm to the right and 10mm to the left considered to require treatment. The right chin deflection was more easily perceived than was the left (P<.05). Chin asymmetry has a great influence on facial esthetics. We found a statistically significant difference between clinicians (orthodontists and general dentists) and laypersons in the cognition of chin asymmetry and the recommendations for treatment.