Analysis of the Predicted Size for Permanent Canine and Premolars / Монголын Анагаах Ухаан

ABSTRACT

Introduction: Among those prediction methods for estimating size of unerupted canine and premolars, Moyers and Tanaka-Johnston methods are most widely used, though the method-using radiograph is more accurate. Significant differences in tooth size exist among different ethnic groups. Therefore, an accurate prediction method for American white maybe less accurate for Mongolians. Objective: The purposes of the study were to develop new regression equations for predicting the size of the unerupted permanent canine and premolars in Mongolian children. Methods: Eighty-four males and eighty-three females in total 167 sets of dental cast of the permanent dentition aged 14.20.96 years were included in this study. The criteria of subjects selecting were following all permanent teeth erupted (third molars may not be present), Angle I class fi rst molar relationship, no fi lling and no caries, no history of orthodontic treatment. The mesio-distal crown diameters were measured with a caliper to an accuracy of 0.05 mm. The data were processed with SPSS16.0 software package. Independent t-test and regression analysis were used for statistical analysis. Results: The development new linear regression equations with predictor sum 21|12 for predicting the size of the canine-premolar segment was based on the normative standard of mesio-distal crown diameters of permanent teeth in Mongolian children. The following new regression equations were developed for unerupted canines and premolars in Mongolian children Y=9.07+0.57*x in maxillary, Y=8.43+0.55*x in mandible arch. Discussion: This study confi rmed that the use of Moyers and Tanaka-Johnston prediction methods for mixed dentition analysis among Mongolian children were unsuitable. Both methods underestimated the size of caninepremolar segments. Conclusions: The following new regression equations were developed for interrupted canine and premolars in Mongolian children y=9.11+0.57*x in maxillary and y=8.43+0.55*x in mandible arch.