Evaluation of Moyers mixed dentition analysis in school children

The purpose of this study is to test the reliability of Moyers mixed dentition analysis in school children.

A study was conducted on a sample of 150 school children within the age group of 13 to 16 years old who had all permanent teeth that were fully erupted. Dental impressions were taken with alginate impression material and immediately poured with dental stone. Mesiodistal dimensions of permanent mandibular incisors, maxillary and mandibular canines, and premolars were measured using a digital caliper with a resolution of 0.01 mm.

The coefficient of correlation (r) was calculated to find the correlation between the sums of the canine, premolars in both arches, and mandibular incisors. A Student's unpaired t test was calculated to compare the tooth dimension between male and female subjects. The actual measurements were compared with the predicted values obtained with the Moyers prediction tables at the 35 th , 50 th , and 75 th percentile confidence levels. A Student's t test was calculated to compare the actual and predicted values. Using this data, linear regression equations were formulated for tooth size prediction. The coefficient of determination [r2] was calculated to find the accuracy of the formulated prediction equations. The standard error of estimate (SEE) was calculated to determine the validity of the proposed equations.

Moyers prediction tables are not an accurate method to estimate tooth dimension in our samples. The mesiodistal crown dimension in the buccal segment of the mandibular arch was larger in males (p=0.04) than in females.

The differences noted between predicted values from the Moyers tables and that of the present investigation is the result of racial and ethnic diversity. The accuracy of the prediction equation should be tested in a larger sample.