A comparison between laypeople and orthodontists in evaluating the effect of buccal corridor and smile arc on smile esthetics

ObjectiveThe purpose of this study was to investigate the effects of buccal corridor space (BCS) and smile arc (SA) on smile esthetics as judged by laypeople and orthodontists, and to identify the threshold where these smile variables became esthetically displeasing.MethodsA color photograph of a female smile was digitally modified to produce six smile images with BCS ranging from 0% to 25% and three smile images with altered smile arcs (consonant, flat, and reverse). These images were shown to 104 laypeople and 52 orthodontists who were asked to rate the attractiveness of each smile on a scale of 1 to 10. Perceptions were compared between laypeople and orthodontists using t-test analysis. A one-way ANOVA post hoc Duncan test was used to establish the threshold at which BCS was considered unattractive by each group.ResultsThe results showed that orthodontists seemed to detect changes in BCS more readily than did laypeople. They rated images with 15% to 25% BCS as significantly less attractive than did laypeople. The threshold at which BCS was considered significantly unattractive by the laypeople and orthodontists was 25%. The most attractive smile as judged by orthodontists and laypeople was the broadest and consonant smile. The image with a reverse smile arc was rated as the least attractive by both groups.ConclusionsIt is advisable to take into consideration the smile arc during orthodontic treatment, because flattening the smile arc has been perceived as more unattractive than small variations in the BCS.