Abstract:

BACKGROUND: Morphological measurement of the tooth buccal and lingual surface measured by three-dimensional measuring instrument and computer-aided system confirms that there are significant differences of the teeth date between Chinese and foreigner. 
OBJECTIVE: To obtain the morphological characters of normal occlusion in Chongqing with the purpose of providing evidence for individual treatment system, and to study the discrimination in tooth profile of different races and various areas, through comparing the data of this study with those of Andrews, other domestic researchers and Ormco lingual brackets.
METHODS: Forty-five casts of non-orthodontic subjects (21 males and 24 females) with normal occlusion were examined using the ATOS three-dimensional lasing scanner system. Then, the data of digital three-dimensional dental casts, including crown angulation, inclination, facial prominence and offset angle of molars both of labial and lingual surfaces of the teeth was calculated and analyzed statistically by computer-aided system. 
RESULTS AND CONCLUSION: Chongqing people had their own ethnic characteristics in normal occlusion: ①the crown angulation of the upper incisors and canines were more upright, while the premolars and molars were medially more inclined compared with Caucasian. ②the upper incisors were inclined more to the labial side, while the upper molars to the lingual side, but the inclination were smaller than that of domestic researchers’ study. ③the facial prominence of molars was larger than that of Caucasian and the facial prominence of canines was larger than domestic researchers’ study. ④the offset angle of upper first molars was smaller, but was similar to that of domestic researchers’ study. Tooth profile in Chongqing was significantly different from that of Caucasian and domestic residents and had their own characteristics. The result can not only provide evidence for straight wire technique and lingual therapy, but also help our clinicians to assess the craniofacial malformation completely and objectively for diagnosis and plan individual treatment for patients from different races and various areas.