The Measurement And Research On Normal Occlusion Modelof Healthy Yizu

[Objective]Orthodontic dental models of 87 untreated healthy Yizu in Yunnan province were evaluated for grading an ideal anatomic occlusion including good dental interdigitation and alignments. The dental models were measured the size of teeth, the dental arch, dental basebone and palate. In order to know morphologic characters of teeth, dental arch and basebone of Yizu, we established norms and ratios on normal permanent occlusion that were undertaken statistics correlation analysis, meanwhile the morphology of dental arch form was analyzed initially.[Method]87 individuals with normal occlusion in the permanent dentition of Yizu were selected within a particular geographic area (Kunming) of Yunnan province, including 40 male and 47 female aged from 17 to 20 years old (their mean age was 18.5 years old ). Impressions were taken of them, providing 87 plasters. The width and the height of the tooth crown, the size of dental arch and dental basebone, the palatal height of each case were measured with the electronic vernier and computed-assistant system. And all data were input into SPSS 12.0 system and were analyzed with statistic correlation analysis method and compared with that of different regions and nationalities. Both Bolton's and Pont's index are whether valuable to clinical application or not.[Result]On the basis of this study of eighty-seven normal occlusion in the permanent dentition cases, we established the norms and ratios in the normal permanent occlusion of Yizu in Yunnan province. The statistic results suggest that there are significant differences between male and female in the size of most teeth, which are more obvious in the shape of canines and in the width of dental arch and basebone. Meanwhile there is no obvious difference between male and female in the length of dental arch and in the basebone. By partial correlation analysis, we discovered that the width and the length of dental arch have a positive relationship, the quantities of upper teeth and the quantities of lower teeth have the same relationship, but Pont's index and the widths of upper dental arch have a significant negative relationship.(Conclusion]The norms and ratios were established on normal permanent occlusion of Yizu in Yun Nan province. There were significant sexual differences in the size of teeth, the width of dental arch and bacebone. This size of Yizu is bigger then Chinese Han's and almost smaller then Tibetan's. The dental arch form is almost quadrate-round. The results of this study could be concluded that Bolton' index was more valuable to clinic then Pont's index.