Importance of interincisal index for predicting mesiodistal crown diameters of canines and premolars.

The aim of this study was to examine the accuracy of regression equation for prediction of the mesiodistal diameter (MDD) of the crowns of canines and premolars (C, P1, P2), and to determine whether an incisal indexs can serve as a reliable predictor. MDD and vestibulooral diameter (VOD) of the crowns of central and lateral incisors (I1, I2), C, both P1, and P2, and first permanent molars (M1) in both jaws were measured on the plaster casts of 150 subjects (75 boys and 75 girls). The obtained measurements were compared and correlated with predicted values (by linear regression equation derived previously), with respect to gender, jaw side and value of the interincisal index. The correlation coefficients between measurements and predicted MDD of the C, P1, and P2 were calculated with respect to gender and jaw. The values varied from 0.62 to 0.81. It could be concluded that normal values of the interincisal index of the I1 and I2 are highly associated with measured and predicted MDD of the C, P1, and P2 crowns. Correlation coefficients ranged from 0.84 to 0.99.