Dynamics of a smile in different age groups

Objective: To evaluate smile in different age groups and to detect gender differences in smile. Materials and Methods: Digital videographic records of 241 randomly selected subjects were obtained for smile analysis. The subjects were divided into four groups by age (15–20 years, 21–30 years, 31–40 years, and 41–50 years). Each group was further subdivided by gender. After 41 subjects were excluded, the smile dimensions of 200 subjects were analyzed by two-way multivariate analysis of variance (MANOVA) with Duncan's multiple range post hoc test. Results: All dynamic measurements (change in upper lip length, upper lip thickness, commissure height, and intercommissural width from rest to smile) decreased with age in both males and females. Changes in upper lip length and commissure height on smiling were greater in males as compared with females of the same age groups. Changes in intercommissural width on smiling were greater in females as compared with males in all age groups. Conclusion: Smile changes with increase in age, and the changes differ between males and females. Females had a wider smile as compared with males of similar age groups.