Regression Equations and Probability Tables for Mixed Dentition Analysis in a Nigerian Population

Abstract

Objectives: The objectives of this study were to evaluate the applicability of both the Moyers and the Tanaka and Johnston mixed dentition space analysis in a Nigerian population, and develop a new probability tables and regression equations for prediction of the size of unerupted canines and premolars in Nigerian population. Methods: The mesiodistal crown dimensions of 54 dental casts of Nigerian subjects were measured with digital calipers. Gender differences were evaluated with independent t-test. Correlation coefficients between the combined mesiodistal widths of the permanent mandibular incisors and the canine and premolars of the maxillary and mandibular arches were determined respectively. Linear regression equations and probability tables were derived and used to compare actual Nigerian tooth widths with those predicted by the Moyer’s probability table and regression equations of Tanaka and Johnston. Results: The regression equations for the maxillary arch males: Y=0.49x+10.98, females: Y=0.47x+12.95, sexes combined: Y=0.47x+11.49, and the mandibular arch males: Y=0.54x+9.53, females: Y=0.39x+12.75, sexes combined: Y=0.51x+10.27 were derived. No statistically significant differences (p>0.05) were observed in the mesiodistal widths of maxillary canine and premolars for combined sexes at 75 th percentile, and in the mandibular arch for male at 85 th percentile confidence levels when compared with those of the Moyers’ probability tables, while there were statistically significant differences (p<0.05) at all the remaining percentile levels. Tanaka and Johnston’s equations underestimated canine and premolars mesiodistal widths in the mandibular and maxillary arches.