Morphometric Variations and Growth Analysis of the Side Face Profiles of Chinese Children

We aim to use geometric morphometric methods to analyze the contours of the side face profile and its variations in 116 children in Hunan province, China, in order to reveal common morphological features and growth of the side face profiles of Chinese children.

We photographed the side faces with consistent standardized procedures. Thirty-seven landmarks were recorded, which comprehensively reflected the facial sagittal plane. The collection of coordinate data regarding landmarks was conducted by tpsDig software. Other analyses, such as average shape analysis, principal component analysis, variations analysis, and allometric analysis, were conducted using tpsRelw and tpsRegr.

Based on the 37 landmarks, principal component analysis was used on the profiles of boys and girls. The result shows that PC1 and PC2 account for 35.46% and 27.44% of the side face contour variations, respectively. There is no significant difference in the side profiles of boys and girls. Overlapping distributions between the boys and girls occurred. A significant difference occurs when principal component analysis was used on the side profiles of children and adults.

There is a significant difference in the side face profiles between adult males and females. Adult males have a higher brow (the 8th landmark) than females, and adult females have a more curved forehead. However, the side face profiles of boys and girls around 10 years of age are generally similar, which suggests that the significant difference in side face profiles between adult males and females may be formed after the age of 10. This study is of great significance for both orthodontists and pediatricians to use different norms for kids and adults and different norms for males and females for each of those age groups.