title: Three-dimensional evaluation of social smile symmetry.
abstract: OBJECTIVE
  To evaluate the social smile symmetry using three-dimensional (3D) stereophotogrammetric images.
  
  
  METHODS
  The study was conducted with 3D facial images of 30 individuals (age range 13-25 years). The rest position was considered as the reference image and the social smile image was aligned on this image using the best-fit alignment method. The spatial differences between the same points established on both images using 3D analyses were determined for right and left points in X, Y, and Z planes.
  
  
  RESULTS
  The highest difference related to spatial distance in right and left points was -0.56 mm (95% confidence interval [CI], -1.19, 0.06 mm) between right and left commissure (Com) points. The difference was not significant, and the Bland-Altman upper and lower limits were -3.85 mm and 2.71 mm, respectively. The highest difference for the transversal plane was found in Com points, similarly to the spatial distance (mean: 0.50 mm, 95% CI, -2.62, 1.02 mm). The differences between the changes in the left and right points in the Y and Z plane were not significant (P > .05).
  
  
  CONCLUSIONS
  The social smile was observed to show asymmetry in varying amounts in the different directions. Asymmetry increases in some cases, specifically for the corners of the mouth.
authors.forename: Gökhan S
authors.initials: GS
authors.lastname: Duran
authors.forename: Furkan
authors.initials: F
authors.lastname: Dindaroğlu
authors.forename: Serkan
authors.initials: S
authors.lastname: Görgülü
mesh_terms: D000293:Adolescent; D000328:Adult; D059925:Anatomic Landmarks; D003196:Computer Graphics; D005145:Face / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D005146:Facial Asymmetry / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D010780:Photogrammetry / Q000379:methods; D011446:Prospective Studies; D012016:Reference Values; D012904:Smiling; D012984:Software; D055815:Young Adult
keywords: 3D stereophotogrammetry; Social smile; Symmetry