Modified Björk Analysis of Lateral Head Radiographs of Southern Chinese

Aim: To establish cephalometric norms for the modified Björk’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 Caucasian 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 statistically 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 Björk’s cephalometric analysis in southern Chinese children were established. The use of specific standards for Chinese and separate for gender, for the modified Björk’ cephalometric analysis seems to be justified.