Impact of incisor display and lower lip height on aesthetic perception and age estimation

Objective: This study investigated the perception of smile attractiveness and age estimation based on different proportions of maxillary and mandibular incisor exposure, combined with changes in lower lip vermilion height. Materials and Methods: Smile photographs were digitally modified to simulate different proportions of incisor exposure combined with reduced or unaltered lower lip vermilion height. A total of 162 evaluators (orthodontists, dentists, and laypersons) rated attractiveness using a 10-point visual analog scale and estimated the apparent age range. The differences between groups were tested by Kruskal-Wallis, chi-square and repeated measures ANOVA, and a linear regression was performed, with p<0.05 as statistically significant. Results: Greater maxillary incisors exposures were considered more attractive by all groups. However, the lower lip vermilion height did not significantly influence esthetic perception or age estimation. Orthodontists were more critical compared to dentists and laypersons. An increase in mandibular incisor exposure was correlated with the attribution of a more advanced apparent age. Older laypersons tended to be more tolerant of smiles showing greater mandibular incisor exposure. Conclusions: These findings suggest that the proportion of maxillary and mandibular incisor exposure plays a significant role in the perception of smile attractiveness and age estimation. Clinical significance: The results not only contribute to our understanding of smile esthetics but also have direct implications for clinical practice in orthodontics and esthetic dentistry, guiding treatment planning and patient communication.