Abstract: Objective To measure and analyze the normal crown facial prominences among people of Han and Mongolian nationality in Hohhot, and to compare the differences of the crown facial prominences between Mongolians and Hans as well as the difference between genders. Methods 80 volunteers with normal occlusion were selected from five universities in Hohhot, among whom 40 were Hans and 40 were Mongolians with both sexes equally represented. The upper and lower jaws of the selected samples were scanned by the GE64 -slice spiral CT machine, and the scan images were measured .Then the differences between right and left sides, genders and ethnicities were observed and compared with paired-t test. Results ①The mean and standard deviation of crown facial prominence among men and women in Han and Mongolian nationality were established. ②The differences n U1、U4、U6、L4 and L5 among males between Mongolian and Han nationality were of statistical significance; the differences in U2、U6、L1 and L7 among females between Mongolian and Han nationality were statistically meaningful. Conclusion During orthodontic treatment, correctional quantity should be adjusted according to the differences in the Mongolians and the Hans and can’t be treated as the same.

Key words: normal occlusion, crown facial prominence, spiral CT, Hohhot