Morphology And Classification Of Youth Maxillary Incisors

[Aim]In this study, according to different methods of classification, the maxillary central incisor digital image of Chinese youth were measurement and classify all the samples. Then represent the shape of each tooth type. To provide reference for making crown compositing aesthetic standard for the tooth defects and dentition defect.[Methods]The shape of maxillary incisors were investigated in 177 healthy individuals by digital photography, age 22-30 years old,85 men,92 women. Take pictur es of maxillary central incisors. Different of image-processing programs were u sed to measure the index. According to the different method we classified all t he samples into groups. And the data were analyzed by ANOVA test whether there was statistical difference between the groups. Then represent the shape of each tooth type by geometric morphometric.[Results]1. In experiment 1, the number of the triangular, round, square maxillary central incisors is 90:77:10. Triangular samples accounted for a large proportio n, square samples number is the smallest, there was significant difference betw een 3 groups of TA/TB value (P＜0.05).2. In the first part of experiment 2, the tree graph analysis in SPSS revea led 3 classifications of crown forms:The number of the triangular, round, squa re maxillary central incisors is 53:107:17. When the CS/CL ratio is less tha n 42.6583%, the tooth is triangular in shape. When the ratio is more than 57.8 067%, the tooth is square in shape. When the ratio is between 42.6583% and 57.8067%, the tooth is defined as round.In the second part of experiment 2, GA was positively correlated with C W. CW/CL and GA, CS/CL and CS/CL were positively correlation. There was significant difference among the 3 groups with respect to CS/CL ratios, CW/ CL ratios.3. In experiment 3, the geometric morphometric can divide all samples int o 3 groups by cluster analysis:group A, group B, group C, containing the nu mber of samples is 57:46:74. The mean shape of each group represent as the 3 tooth type.[Conclusions]1. The Tufts University classification index is applicable to the samples i n this research. There is correlation between tooth type and the position of the mesial contact area of maxillary central incisors. The position of the mesial c ontact area of triangular group is lower than the other two groups.2. The classification of maxillary central incisor by geometric measurement is feasible; It can provide the shape of each tooth type.