Analysis of dentofacial characteristics in Han Chinese adults with facial harmony

Objective·To establish Downs cephalometric norms for the Han Chinese aged 18‒25 with harmonious faces, and to analyze gender and regional characteristics.Methods·A stratified sampling approach was used to recruit participants from seven geographic regions across China. Over 30 000 volunteers were screened, and 883 participants with harmonious faces were ultimately included. Basic demographic data were collected, and lateral cephalometric radiographs were taken. Hard tissue measurements were performed with Downs analysis (using anatomical porion). The data were then statistically analyzed to compare gender and regional differences in dentofacial structures.Results·The gender differences in the four hard tissue measurements, the angle of convexity, A-B plane angle, mandibular plane angle, and occlusal plane angle, were statistically significant (P<0.001). Females showed larger values for the angle of convexity, mandibular plane angle, and occlusal plane angle, but smaller values for the A-B plane angle, compared to males. The gender differences in the interincisal angle, L1 to occlusal plane, L1 to mandibular plane, and U1 to AP plane were not statistically significant. There were regional differences in all 10 measurements of Downs analysis, though some regions shared common features. Specifically, the northeastern, eastern, and southern coastal regions exhibited a smaller facial angle, and larger mandibular plane angle, angle of convexity, occlusal plane angle, and U1 to AP plane. It suggested that, compared to inland regions, individuals from coastal regions tended to have more retrusive chins, steeper mandibular planes, more prominent upper incisors, and more convex hard tissue profiles.Conclusion·Gender differences exist in the dentofacial hard tissue structures of Han Chinese adults with harmonious faces, primarily in skeletal measurements. Each region has its unique dentofacial characteristics, along with some common features. These differences should be taken into account in clinical diagnosis and treatment for the development of personalized and precise therapeutic strategies.