Mixed Dentition Space Analysis for Jordanians: Comparison of Two Methods

Objectives: To test the reliability of the Moyer's probability tables and the Tanaka and Johnston equations in Jordanians and coefficients of correlation between the combined mesiodistal widths of the permanent four mandibular incisors and the combined widths of the canine and premolars of the maxillary and mandibular quadrants. Methods: The dental models of the dentition of 130 male and 96 female Jordanian subjects (14-16 years) with complete permanent dentition were randomly selected. The mesiodistal width of the mandibular four permanent incisors, maxillary and mandibular canines and premolar teeth were measured using a vernier guage caliper to the nearest 0.1mm. The actual teeth measurements were then compared with the predicted values derived from the Tanaka and Johnston equations and Moyers probability tables. Correlation and linear regression analyses were performed between the predicted and actual tooth size for Jordanian children and standard regression equations were developed. Results: Except for the maxillary arch in males, Tanaka and Johnston regression equations underestimated the mesiodistal widths of permanent canines and premolars. On the other hand, there were no statistically significant differences between actual mesiodistal widths of canines and premolars and the predicted widths from Moyer's charts at the 65% and 75% level for the lower and upper arches in males and at the 85% level for the upper and lower arches in females. For the newly developed regression equations, the correlation coefficients between the sum of the mandibular four incisors and the sum of the canine and premolars were 0.60 (for lower) and 0.51 (for upper) in males and 0.59 and 0.64 respectively in females. Conclusions: 1. Tanaka and Johnston prediction method was not accurate when applied to a Jordanian population. 2. Moyers method for prediction can be used for Jordanian children at different probability levels for males and females.