Does the presence of unilateral maxillary incisor edge asymmetries influence the perception of smile esthetics?

Abstract

Objective: Determine orthodontists and laypersons' perception of maxillary central and lateral incisor edge asymmetries in full-face and close-up smiles.

Material and methods: Four smile photos were selected for this study: two full-face and two close-up smile photos of two male subjects, a white man and an Afro-descendant man. Both were considered pleasant smiles, following some principles of an ideal smile. Images were digitally altered to create tooth wear asymmetries on the maxillary left central and lateral incisor in 0.5 mm increments. Final images were arranged randomly into a photo album and were shown to 86 judges (43 orthodontists and 43 laypersons). Judges were asked to evaluate the attractiveness of the images according to a visual analog scale. Data were statistically analyzed using one-way analysis of variance (ANOVA) with the Tukey's post hoc test and the Student t test.

Results: There was no statistically significant difference in the mean esthetic scores of the full-face and close-up smile photos. The most attractive smiles were those without asymmetries and those with 0.5 mm wear in the lateral incisor, whereas the least attractive ones were those with 1.0-1.5 mm wear in the central incisors. Statistically significant difference was found in the mean scores given by the judges in most cases. The orthodontists were more critical and assigned lower scores than the laypersons.

Conclusions: The presence of maxillary incisor asymmetries is a critical factor influencing the perception of smile esthetics. The most attractive smiles of the men investigated were those without asymmetry and those with 0.5 mm incisor edge asymmetry in the lateral incisor.

Clinical significance: The presence of incisal asymmetries (especially in maxillary central incisors) negatively influences smile esthetics, corroborating the clinical hypothesis that the closer to the facial midline, the greater the need for symmetry.

Keywords: anterior restorations; orthodontics; smile; smile esthetics.