Reliability of Moyer’s and Tanaka Johnston’s prediction methods in a non-Caucasian heterogeneous population – a cross-sectional study

Abstract

Introduction: Mixed dentition analyses are used to determine possible tooth-size and arch-length discrepancies during the transition from primary to permanent dentition. Prediction methods using a probability table or linear regression equation use the sum of the mesiodistal widths of mandibular permanent incisors to predict the mesiodistal width of unerupted permanent teeth. Racial and sexual variations and sexual dimorphism in tooth size have been reported. The objective of this study is to validate Moyer’s and Tanaka Johnston’s mixed dentition analyses in a contemporary South Indian population. Materials and methods: 100 pairs of permanent dentition models belonging equally to both sexes with an age range of 12–21 years comprised the sample in which both analyses were done. The predicted width of permanent canines and premolars was compared to the actual width in the study models. Results: There was a statistically significant difference between the two values for Moyer’s analysis in the mandibular teeth of females (p=0.04), 95% CI −0.605 to −0.969. There was a statistically significant difference between the two values for Tanaka Johnston’s analysis of maxillary teeth (p=0.001), 95% CI 0.863 to 1.370. Conclusions: Moyer’s analysis shows a statistically significant underestimation in the mandibular arch of females. Tanaka Johston’s analysis shows a statistically highly significant overestimation in the maxilla. Both analyses cannot be reliably applied to the South Indian population.