Introduction

Facial analysis of soft tissue using 3D stereophotogrammetry can contribute to the process of facial identification through the smile.

Aim

To compare measures of linear, angular and area variables in three-dimensional images of the lip's soft tissues between gender and age, to contribute to the process of human face identification based on smile images.

Methods

The total sample consisted of 120 Brazilian subjects, 60 men and 60 women, divided into three different age groups: 18 to 35 years; 36 to 50-years-old and 50 to 70-years-old (20 male volunteers and 20 women in each age group, male and female). 32 points were marked on the face, after that 3D images were taken (Vectra® H1, Canfield Scientific, Parsippany, NJ, USA) and linear, angular and area measures of the lip's soft tissue were analyzed (ANOVA, p < 0.05 as significance).

Results

Age showed more expressive differences when compared to variables between genders. This can be analyzed since the variables of the upper and lower lip vermilion area, mentolabial angle, upper lip vermilion height and lower lip vermilion height presented the values of p = 0.01, respectively; 0.02; 0.04; 0.0001; 0.002; while in relation to gender, only the nasolabial angle variable had a p-value of 0.03.

Conclusion

In conclusion, the variations that can be observed through three-dimensional images in soft tissue of the lips are only significant when comparing different age groups. Several analysis techniques for human identification based on smile images have been studied and developed, and these results indicate that perioral soft tissue variations can be a comparison variable focused only on age estimation and should not be considered in the estimation of gender.