Influence of incisor display and lower lip height on smile esthetics and perceived age

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.

Smile photographs were digitally modified to create images with varying proportions of incisor exposure (100%, 80%, 60%, 40%, and 20% maxillary incisor exposure) and reduced or unaltered lower lip vermilion height. A total of 162 evaluators, including orthodontists, dentists, and laypersons, rated attractiveness using a 10-point visual analog scale and estimated the apparent age range (<30, 30-50, >50).

Maxillary incisor exposure significantly affected smile attractiveness, with higher exposure levels (100% and 80%) receiving higher attractiveness scores across all evaluator groups (p < 0.05). Reduction in lower lip vermilion height did not result in statistically significant differences in attractiveness ratings or age estimation (p > 0.05). Orthodontists assigned significantly lower attractiveness scores than dentists and laypersons (p < 0.05). Increased mandibular incisor exposure was significantly associated with the perception of an older apparent age (p < 0.05). Older laypersons demonstrated greater tolerance toward smiles with increased mandibular incisor exposure (p < 0.05).

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. Furthermore, they highlight the importance of considering individual preferences in dental treatment planning. The results of this study have direct implications for clinical practice in Orthodontics and Esthetic Dentistry, providing valuable guidance for treatment planning and patient communication.