Modified Björk Analysis of Lateral Head Radiographs of Southern Chinese

Abstract

Aim: To establish cephalometric norms for the modified Bjork's cephalometric analysis in southern Chinese children, and compare them to those of a matched Caucasian sample. Materials and Methods: The material comprised lateral cephalometric radiographs of a random sample of 200 males and 205 females 12-year-old southern Chinese, and an additional sample of 43 males and 43 females 12-year-old British Cau- casian children in Hong Kong. The radiographs were digitized twice with the Computer-Assisted Simulation System for Orthognathic Surgery (CASSOS) program. Results: The results showed that there were statistically significant ethnic differences for 15 out of the 17 cephalometric variables (P<0.05-0.001). There were statistically significant ethnic differences for 11 variables in males (P<0.05-0.001) and 15 variables in females (P<0.05-0.001). The size of the statistically significant gender differences varied from -0.4 to 0.8 (P<0.05-0.001) in SD scores for Chinese and from 0.5 to 0.6 (P<0.01) for Caucasian. The size of the observed statisti- cally significant ethnic differences varied from -1.7 to 1.3 (P<0.05-0.001) in SD scores for female and from -1.6 to 1.0 (P<0.05-0.001) for male. Conclusion: Cephalometric norms for the modified Bjork's cephalometric analysis in southern Chinese children were es- tablished. The use of specific standards for Chinese and separate for gender, for the modified Bjork' cephalometric analy- sis seems to be justified.