The Impact of Midline Deviation on Smile Attractiveness: A Cross-Sectional Study Among Laypersons

Objective This study aimed to assess laypersons' perceptions of smile aesthetics in relation to upper dental midline deviations and to determine whether adjacent facial structures influence their judgments. Methodology A cross-sectional study was conducted using two sets of photographs depicting midline deviations. The first set included six images showing only the lips, while the second set featured six images displaying the lips, chin, and two-thirds of the nose. Both sets presented deviations at increments of 0 mm (no shift), 1, 2, 3, 4, and 5 mm relative to the facial midline. The photographs were randomly labeled (A-F) and presented in a nonsequential order to prevent bias. Laypersons rated the attractiveness of each smile on a scale of 1 (very unattractive) to 10 (very attractive). Data were tabulated and analyzed using SPSS software version 22 (IBM Corp., Armonk, NY). Results Responses from 242 laypersons (127 females and 115 males) revealed that midline deviations of up to 3 mm were considered aesthetically acceptable across both photo sets. Friedman's test indicated statistically significant differences in ratings for each midline shift in both groups (P < 0.001). However, no significant differences were observed between ratings for smiles showing only the lips and those including the lips, chin, and nose. Additionally, gender and age did not significantly influence perceptions of smile attractiveness. Conclusions Laypersons perceive midline deviations of up to 3 mm as attractive, regardless of whether adjacent facial structures are included in the images. These findings suggest that the presence of additional facial features does not significantly alter aesthetic judgments of midline deviations.