title: Smile line assessment comparing quantitative measurement and visual estimation.
abstract: BACKGROUND
  Esthetic analysis of dynamic functions such as spontaneous smiling is feasible by using digital videography and computer measurement for lip line height and tooth display. Because quantitative measurements are time-consuming, digital videography and semiquantitative (visual) estimation according to a standard categorization are more practical for regular diagnostics. Our objective in this study was to compare 2 semiquantitative methods with quantitative measurements for reliability and agreement.
  
  
  METHODS
  The faces of 122 male participants were individually registered by using digital videography. Spontaneous and posed smiles were captured. On the records, maxillary lip line heights and tooth display were digitally measured on each tooth and also visually estimated according to 3-grade and 4-grade scales. Two raters were involved. An error analysis was performed. Reliability was established with kappa statistics.
  
  
  RESULTS
  Interexaminer and intraexaminer reliability values were high, with median kappa values from 0.79 to 0.88. Agreement of the 3-grade scale estimation with quantitative measurement showed higher median kappa values (0.76) than the 4-grade scale estimation (0.66). Differentiating high and gummy smile lines (4-grade scale) resulted in greater inaccuracies. The estimation of a high, average, or low smile line for each tooth showed high reliability close to quantitative measurements.
  
  
  CONCLUSIONS
  Smile line analysis can be performed reliably with a 3-grade scale (visual) semiquantitative estimation. For a more comprehensive diagnosis, additional measuring is proposed, especially in patients with disproportional gingival display.
authors.affiliation: Department of Orthodontics and Oral Biology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors.forename: Pieter
authors.initials: P
authors.lastname: Van der Geld
authors.forename: Paul
authors.initials: P
authors.lastname: Oosterveld
authors.forename: Jan
authors.initials: J
authors.lastname: Schols
authors.forename: Anne Marie
authors.initials: AM
authors.lastname: Kuijpers-Jagtman
mesh_terms: D000328:Adult; D005881:Gingiva / Q000033:anatomy & histology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008046:Lip / Q000033:anatomy & histology; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D023861:Photography, Dental; D012904:Smiling; D013223:Statistics as Topic; D014070:Tooth / Q000033:anatomy & histology; D014741:Video Recording; D014796:Visual Perception; D055815:Young Adult