New regression equations for mixed-dentition arch analysis in a Turkish sample with no Bolton tooth-size discrepancy.

INTRODUCTION

Our objectives were to establish new regression equations derived from 228 Turkish patients (100 boys, 128 girls) with no intermaxillary tooth-size discrepancy that would give the greatest correlation coefficient for the sum of permanent tooth widths of the canines and the premolars of both jaws, according to sex, and to compare our new data with those from other studies.

METHODS

Mesiodistal tooth widths were measured from dental casts. Student t tests were carried out to compare tooth sizes between the sexes and the right and left sides of the arches. The constants a and b in the standard linear regression equation (y = a + bx), the correlation coefficients (r), the coefficients of determination (r2), and the standard errors of the estimates (SEE) were calculated.

RESULTS

Statistically significant differences were found between the widths of teeth between the sexes in both the maxillary (P <0.01) and mandibular (P <0.001) arches. The r value was 0.956 to 0.989, with the higher coefficients in the girls. The r2 values were 91% in boys and 98% in girls, and the SEE was better in the maxilla and the mandible (0.013 mm) for the girls. The regression equations produced predictions of mesiodistal width summations for the maxillary and mandibular canine and premolar segments that were much different from other reported studies.

CONCLUSIONS

New regression equations were derived for Turkish people. The prediction equations and probability tables should be revised by using subjects with no tooth-size discrepancy.