A Primary Study Of Establishment And Application Of Tanaka-Johnston Analysis In Shanghai Adolescent

OBJECTIVE: The aim of this study was to develop Tanaka-Johnston prediction method for Shanghai adolescent population,which could be used to predict the widths of permanent premolars and canines by the sum of the widths of the four mandibular incisors.METHODS: A total of 288 models(132 men and 156 female)aged from 12-20 years were selected from patients seeking orthodontic treatment in department of Oral Orthodontics in the Ninth People ’s Hospital,Shanghai Jiaotong University School of Medicine.After carefully measurement of the widths of the teeth,the following values were calculated: total mesio-distal width of mandibular incisors(ΣL2112),total mesio-distal width of unilateral maxillary canine and premolars(ΣU345),total mesio-distal width of unilateral mandibular canine and premolars(ΣL345).All statistical analysis was performed with SPSS 23 statistical software.The paired sample t-test and correlation analysis were carried out and the Tanaka-Johnston prediction equation of Shanghai adolescent population was obtained.The accuracy of the prediction equation is compared by residual analysis and compared with the Moyers prediction table and the linear regression equation.RESULTS: There is a significant statistical gender duality in the measured tooth size in Shanghai adolescent population,indicating the importance of different using of the mixed dentition prediction by gender.After the paired sample t-test of the left and right sides of mandibular arch showing no statistical differences,the Tanaka-Johnston prediction equation of Shanghai adolescent population was found: for male in the maxillary: Y = 0.5X +11.5,and in the mandibular: Y = 0.5X +10.7;For female in the maxillary: Y = 0.5X + 11.2,and in the mandibular: Y = 0.5X + 10.1.There were differences between the new prediction equation and the original Tanaka-Johnston prediction equation and the Moyers prediction table.70%-78% of the prediction error of this study is within 1mm.CONCLUSIONS: Based on the measurement of adolescent population in Shanghai,this study modified Tanaka-Johnston prediction equation,and the accuracy and reliability of the equation are verified by comparison with other methods.