Analysis of smile esthetics in American Board of Orthodontic patients

Objective: To investigate the common denominators of an esthetically pleasing smile in patients who were considered to be successfully treated upon the submission to American Board Orthodontics (ABO) clinical examination. Material and Methods: A total of 462 patients were examined. Ninety subjects that fulfilled the inclusion criteria were included. Standardized digital smile photographs of the subjects were rated by 30 panel members, including orthodontists, general dentists, and parents of orthodontic patients, using a numeric version of the visual analog scale. Three groups were formed using the mean esthetic score ± standard deviation range: unattractive (n  =  21), average (n  =  47), and attractive (n  =  22) smiles. Eleven smile characteristics were digitally measured on the photographs and compared between the groups using one-way analysis of variance and χ2 tests. Additionally, regression analyses were used to investigate the association of the smile characteristics with the esthetic score. Results: A significant difference was found between the three groups for the comparison of smile arc relationship (P < .001). When all the variables used in this study were entered in the regression analysis, a positive association was found (r  =  0.658; r2  =  0.434; P < .001). Additionally, two models were defined using stepwise regression. The first model included the smile arc (r  =  0.478; r2  =  0.228; P < .001), and the second model had both the smile arc and right gingival display/visible dentition display ratio (r  =  0.567; r2  =  0.321; P < .001). Conclusions: A harmonious smile arc relationship and less gingival display during a smile are significantly associated with smile attractiveness in patients considered successfully treated according to ABO standards.