Three-dimensional analysis of labial morphology: effect of sex and age

Morphological changes in the lips during ageing, including labial volume, area and thickness were assessed in healthy individuals. 40 healthy volunteers (20 men and 20 women) were selected and divided into two groups according to age: 21-34 years ('youthful' group) and 45-65 years ('aged' group). Three-dimensional (3D) stone labial models were made, digitized, and 3D virtual reproductions obtained. Labial thickness, vermilion area, and volume of the upper and lower lips were measured from the digital reconstructions. The data were compared using three-way ANOVA. All data were significantly larger in men than in women (p<0.05), the lower lip was thicker than the upper lip (p<0.001). A significant effect of age for labial thickness and area were found (p<0.001 and p=0.014): the youthful group had higher values than the aged group. Upper to lower lip ratios were not significantly different between sexes or ages. Generally, young people have a larger lip area and thickness than aged ones and men had larger lips than women. The upper/lower lip ratios for area and volume were similar in the two genders.