Analysis of smile exposure and related factors in young people aged 20 to 30 with convex facial profiles

To study smile exposure in 20- to 30-year-olds with convex facial profiles and to explore the correlation between smile exposure and other aesthetic indicators, as well as psychological factors.

This study obtained ethical approval from the hospital. After they gave informed consent and portrait authorization, 80 young subjects aged 20-30 with convex facial profiles had their dynamic postural smile and spontaneous laughter recorded. The videos were imported into Photoshop CC software, key frames were selected, and the smile exposure was measured. The three-dimensional information of the subject's face in a resting state was obtained, the relevant aesthetic indicators were measured, and the satisfaction degree of their smile and laughter were evaluated. Correlation analysis was conducted for smile exposure and the relevant aesthetic indicators and subjective psychological evaluation.

There were statistically significant differences in smile exposure, smile patterns, relevant aesthetic indicators and subjective psychological evaluation between males and females aged 20 to 30 (P< 0.05). There was a large gap between males and females in the average opening degree when laughing, males having 5 times that of females, while the average gingival exposure height of the maxillary central incisor in males was approximately 1/2 of that in females. The average nasolabial angle of males (99.80°± 7.96°) was larger than that of females (96.26° ± 7.31°) (P< 0.05), while the average ratio of upper lip length to the length of the lower 1/3 of the face of males (33.73%±2.35%) was less than that of females (38.57%±2.76%) (P< 0.05). The average psychological score of males (57.75±13.46) was higher than that of females (53.69±17.95) (P< 0.05). The ratios of maxillary teeth and gingival exposure to oral fissure in the postural smile were positively correlated with the nasolabial angle. The oral fissure width in spontaneous laughter was negatively correlated with psychological score.

Convex-faced males and females aged 20 to 30 have different smile exposures and smile patterns. Males tend to smile more openly with a larger opening and less gingival exposure, while females tend to grin with a small opening and more gingival exposure. Smile exposure is positively correlated with nasolabial angle and negatively correlated with smile satisfaction.