The Proportional Relationship Among the Aesthetic Units of the Upper Lip: A 3-Dimensional Morphological Analysis of Young Adults

A deep understanding of the proportional relationship among the crucial aesthetic units of the upper lip is essential for lip treatment procedures, yet limited information can be found. The authors used 3-dimensional (D) photogrammetry to analyze the proportional features involving different lip structures. One hundred sixty volunteers (aged 18-35 y) were included, and standardized frontal view 3D images were obtained. A series of anthropometric parameters were measured, including linear, angular, and ratio parameters. The authors took the philtrum as one structure of particular concern. The philtrum was classified into 4 groups according to the shape of philtral columns, and philtrum depth was measured. The authors analyzed the correlations between the philtrum and the vermillion lip. They found significant differences in philtrum depth among different type groups. A significant negative correlation between philtral depth and philtrum length was found, which indicated that a long philtrum was more likely to be accompanied by a flat philtrum with shallow depth. The philtrum width was significantly correlated with the mouth width with a mean ratio of 0.25. The authors also found a significantly negative correlation between philtral depth and angle of Cupid's bow's peak (Achp), and a positive correlation between Achp and mouth width. This study used 3D photography to quantitatively analyze proportional characteristics among labial aesthetic units in young Chinese adults. The results showed that the philtrum and the vermillion lip morphology were closely related, providing helpful references in perioral procedures.