Proportional analysis of the facial profile in natural head position in Caucasian and Chinese children.

A proportional analysis of the facial soft tissue profile in natural head position involving 11 indices (ratios), was applied to 80 Caucasian, and 80 Chinese male and female 12-year-old children in Hong Kong. The analysis is based on the true horizontal and the porion vertical, and has the advantage that its foundation lies on a more stable (less growth affected) region of the head compared to profile soft tissue landmarks. Measurements were made on cephalograms recorded in natural head position. Male subjects were larger than the females for most of the horizontal measurements, but for both population samples the vertical measurements displayed virtually no significant intersex differences at 12 years. No very significant intersex differences were found for the proportional indices. Ethnic differences were mainly found with the horizontal measurements. Relative to the porion vertical the Caucasian children were more protrusive over soft tissue nasion, nose tip, and sulcus labialis superior, whilst the Chinese displayed more protrusion over the lower lip and sulcus labialis inferior. Ethnic proportional differences relative to nasion were combined with a shorter porion-nasion distance in the Chinese as compared with the Caucasian children. The sella-nasion line was found to be more forwards-upwards inclined in Chinese than Caucasian children. It was concluded that a proportional soft tissue profile analysis, based on natural head position, is a useful method for the comparison of ethnic population groups. This study amplified ethnic differences previously reported by Cooke (1986) and Cooke and Wei (1989).