New Equations for Egyptian Children Based on Tanaka and Johnston Mixed Dentition Analysis

Abstract

Background: The role of different ethnic backgrounds in mixed dentition analyses cannot be overlooked and a customized means of diagnosis should be the goal of every population. Objective:This study aimed at investigating the applicability of the Tanaka and Johnston mixed dentition analysis as a diagnostic aid in Egyptian children and deriving new equations, if relevant.Materials and methods: 180 pairs of stone casts of 13-16-year-old children were traced using TracerNet software. The predicted sum of sizes of 345 from Tanaka and Johnston equations was compared to the actual sum and two regression equations were derived and compared.Results: There was a significant difference between the actual and predicted sizes of teeth; p<0.05. The derived equations for the upper and lower arches were significant; p=0.008 and p<0.001; respectively. They were also significantly different from the tested equation and had a lower mean square error. The mean square error of the derived equations was 4.10 and 6 for the upper and lower arches; respectively, while the Tanaka and Johnston lower arch equation had a mean square error of 9.93 and 12.86 for the upper arch.Conclusions : Tanaka and Johnston analysis could not be an accurate diagnostic aid for Egyptian children and new more accurate and specially tailored equations were derived.