Applicability of two non-radiographic tooth size prediction methods of unerupted permanent canine and premolars, for Galle district, Sri Lanka

Abstract

Introduction: Mixed dentition space analysis necessitates accurate prediction of size of the unerupted permanent teeth. The methods commonly employed are the radiographs, correlation and regression equations, or a combination. Much interest was developed on the application of prediction tables and regression equations to avoid the radiation exposure. However, the predicted values and equations have been reported to be inaccurate on populations other than on which they were developed on. We intended to evaluate the applicability of the Moyer’s probability table and Tanaka Johnston equation in estimating the mesiodistal widths of mandibular and maxillary permanent canines and premolars in adolescents of the Galle District. Material and Methods: Data were collected from study models of 318 randomly selected school students aged 13– 16 years with fully erupted, intact dentitions and no significant malocclusion. The measurements were obtained by a digital caliper with a Vernier scale calibrated to the nearest 0.01 mm. The data were subjected to statistical analysis to compare the actual and predicted values from Moyer’s probability table and Tanaka Johnston equation. Results: There was a statistically significant difference when Pearson correlation two-tailed significance test was used. The actual mesiodistal width of permanent canines and premolars and predicted widths from Moyer’s probability chart at all levels for males and females showed a statistically significant difference at 0.01 level. The values from Tanaka Johnston equation also showed a statistically significant difference at P = 0.01/R = 0.47. Conclusion: Moyer’s prediction table and Tanaka Johnston equation must be carefully used for children in Galle District, Sri Lanka. Therefore, it might be safer to develop regression equations for our population.