| Objective: Through measuring and analyzing the study models of teenage patients with permanent occlusion in Shijiazhuang,this study is aim to find out the sex difference,group difference,distribution of numer and the prevalence rate of abnormal Bolton index in Angle Class I,II,III malocclusion groups,in the meantime the regressive equations and the cartesian coordinate graph about linear regression relationship beteewn intermaxillary tooth-size of normal Bolton index were made,providing reference to clinical diagnosis, treatment and prognosis designed in orthodontics.Method: 972 cases of malocclusion dental study model meeting the requirements of teenage patients with permanent occlusion in Shijiazhuang were selected,including the subjects of Angle class I,II and III. Each tooth crown mesiodistal size between the first molar and the opposite molar of 972 dental cases was measured by calliper. Anterior ratio (AR) and overall ratio(OR) were calculated on the basis of data inputed to computer , according the Chinese normal Bolton index(AR 78.8%士1.72%, OR 91.5%士1.51%), then were analysed with statistic methods. 972 cases were divided into an oversized, a normal and an undersized group according to the Bolton normal value pins or minus one standard deviation, then statistic analysis was got about the sex difference,group difference,distribution and the prevalence rate of abnormal Bolton index in Angle Class I,II,III malocclusion groups,then the cartesian coordinate graph about linear regression relationship beteewn intermaxillary tooth-size of normal Bolton index with the aid of drafting software Metlab was made.Result:1 Anterior ratio and overall ratio analysis1.1 sex difference1.1.1 Anterior ratio: no statistically significant sex difference was found about anterior ratio in each malocclusion group(P>0.05, P>0.05, P>0.05), but the mean of the male was lager than that of the female in Angle class III. ,and the means of the female was lager than those of the male in Angle class I,II.1.1.2 Overall ratio: no statistically significant sex difference was found about overall ratio in each malocclusion group(P>0.05, P>0.05, P>0.05), but the mean of the male was lager than that of the female in each Angle malocclusion group.1.2 Group difference: the mean of anterior ratio in Angle class II was the largest , then that in Angle class I, the mean in Angle class III was the smallest. The mean of overall ratio in Angle class III was the largest , then that in Angle class I, the mean in Angle class II was the smallest. Statistically significant group difference was not found about overall ratio nor anterior ratio(P>0.05, P>0.05).2 The distribution of number2.1 Difference in each malocclusion group2.1.1 The distribution of number about anterior ratio: the distribution of number in each Angle malocclusion group was as follows: the number of patients with normal Bolton index was the largest, then that with undersized Bolton index, it was the smallest with oversized Bolton index.Statistically significant difference was found in each Angle malocclusion group(P<0.01, P<0.01, P<0.01).2.1.2 The distribution of number about overall ratio: the distribution of number in Angle class I,III was as follows: the number of patients with normal Bolton index was the largest, then that with oversized Bolton index, it was the smallest with undersized Bolton index. The distribution of number in Angle class II was as follows: the number of patients with normal Bolton index was the largest, then that with undersized Bolton index, it was the smallest with oversized Bolton index. Statistically significant difference was found in each malocclusion Angle group(P<0.01, P<0.01, P<0.01).2.2 Group difference about the proportion of patients with abnormal Bolton index: statistically significant group difference was not found about the proportion of patients with abnormal anterior ratio nor with abnormal overall ratio(P>0.05, P>0.05).2.3 The proportion of patients with abnormal Bolton index in overall malocclusion cases of the sample was as follows:in the sample including 972 cases,the proportion of patients with normal anterior ratio is 52.67%, and that with undersized one is 28.81%, the proportion of patients with oversized one is18.52%, so the proportion of patients with abnormal anterior ratio is 47.33%; while the proportion of patients with normal overall ratio is 61.32%, and that with undersized one is 18.62%, the proportion of patients with oversized one is 20.06%, so the proportion of patients with abnormal overall ratio is 38.68%.3 Analysis of linear regression relationship between intermaxill- ary tooth-size with normal Bolton index3.1 Normal anterior ratio3.1.1 Sex difference in each Angle malocclusion group: statistically significant linear regression relationship between intermaxillary anterior tooth-size were both in male cases and female ones with normal anterior ratio in each group (the male cases in Angle classI,II,III:the coefficient of regression P<0.01,P<0.01,P<0.01;the female cases in Angle classI,II,III:the coefficient of regression P<0.01,P<0.01,P<0.01), but no statistically significant sex difference was found in each group(in Angle class I: group*maxillary anterior tooth-size P>0.05, group P>0.05; in Angle class II: group*maxillary anterior tooth-size P>0.05, group P>0.05; in Angle class III: group*maxillary anterior tooth-size P>0.05, group P>0.05).3.1.2 Group difference:no statistically significant group differe- nce was found about linear regression relationship between intermaxillary anterior tooth-size with normal anterior ratio among the three malocclusion groups(group*maxillary anterior tooth-size P>0.05, group P>0.05).3.2 Normal overall ratio3.2.1 Sex difference in each group in each Angle malocclusion group: significant linear regression relationship between intermaxillary overall tooth-size were both in male cases and female ones with normal overall ratio in each group(the male cases in Angle classI,II,III:the coefficient of regression P<0.01,P<0.01,P<0.01;the female cases in Angle classI,II,III:the coefficient of regression P<0.01,P<0.01,P<0.01), but no statistically significant sex difference was found in each group(in Angle class I: group*maxillary overall tooth-size P>0.05, group P>0.05; in Angle class II: group*maxillary overall tooth-size P>0.05, group P>0.05; in Angle class III: group*maxillary overall tooth-size P>0.05, group P>0.05).3.2.2 Group difference: no statistically significant group difference was found about linear regression relationship between intermaxillary overall tooth-size with normal overall ratio among the three malocclusion groups(group*maxillary overall tooth-size P>0.05, group P>0.05).4 The linear regression equation between intermaxillary teeth-size with normal Bolton index4.1 The linear regression equation between intermaxillary anterior tooth-size with normal anterior ratio: Statistically significant linear regression relationship was found between intermaxillary anterior tooth-size(the coefficient of regression P<0.05).The linear regression equation was: Y1=0.776X1+0.612, (X1: maxillary anterior tooth-size, Y1: mandibular anterior tooth-size).4.2 The linear regression equation between intermaxillary overall tooth-size with normal overall ratio Statistically significant linear regression relationship was found between intermaxillary overall tooth-size(the coefficient of regression P<0.05).The linear regression equation was: Y2=0.899X2+1.661, (X2: maxillary overall tooth-size, Y2: mandibular overall tooth-size).5 The cartesian coordinate graph about linear regression relationship beteewn intermaxillary tooth-size of normal Bolton index were drafted(Fig. 10, Fig. 11).Conclusion:1 No significant sex differences was found about the anterior and overall ratios in Angle class I,II,III.2 The number of patients with normal anterior ratio was the largest, while it was the smallest with undersized one in each Angle group. The number of patients with normal overall ratio was the largest in each Angle group, while it was the smalleat with undersized overall ratio in Angle class I,III, contrarily it was the smallest with oversized overall ratio in Angle class II. The proportion of patients with abnormal Bolton index existed.3 The linear regression equation between intermaxillary anterior tooth-size with normal anterior ratio was: Y1=0.776X1+0.612,(X1: maxillary anterior tooth-size, Y1: mandibular anterior teeth- size).The linear regression equation between intermaxillary overall tooth-size with normal overall ratio was: Y2=0.899X2 + 1.661, (X2: maxillary overall tooth-size, Y2: mandibular overall tooth-size).4 The cartesian coordinate graph about linear regression relationship beteewn intermaxillary tooth-size of normal Bolton index were drafted,providing a more concise and intuitive method for clinical application of Bolton index.
|
PDF Full Text Request