Cephalometric norms of Chinese: modified Bjork's analysis

Abstract

AIMS: To establish cephalometric norms for Chinese using modified Björk’s analysis (1947) and compare them with those of Caucasians. MATERIALS AND METHOD: Lateral cephalometric radiographs taken in natural head posture of a random sample of 200 male and 205 female 12-year-old southern Chinese together with 43 male and 43 female 12-year-old British Caucasians in Hong Kong. The radiographs were digitised twice with the CASSOS program. RESULTS: In males, the inter-incisal angle, A,B on OP and SN length were significantly larger in Caucasians than in Chinese. On the other hand, the SNA, SNB, SN/MnPl, SN/MxPl, SN/Ui, Ui/MxPl, Li-APo, upper face height and upper and lower lip to E line were significantly larger in Chinese males than in Caucasian males. For females, NSBA, ANB, inter-incisal angle, A,B on OP and SN length were significantly larger in Caucasian than in Chinese. On the contrary, SNA, SNB, SNPg, SN/MnPl, SN/MxPl, SN/Ui, Ui/MxPl, Li-APo, upper and lower face height, and upper and lower lip to E line were significantly larger in Chinese females than in Caucasian females. CONCLUSIONS: There are significant differences between Caucasians and Chinese when using the modified Björk’s analysis.