The effect of dentin depth on the permeability and ultrastructure of primary molars.

The purpose of this study was to measure the permeability of primary molar and permanent premolar dentin at various thicknesses from the pulp and to correlate permeability with the tubule density and diameter of dentin using SEM. The data were examined for statistically significant differences using two-way analysis of variance, multiple comparison Scheffe, and regression analysis. The permeability of all teeth increased with decreasing dentin thickness. The removal of the smear layer resulted in a significant increase in the permeability. However, the permeability of the dentin in premolars was significantly higher than that in the primary molars. The density and diameter of the dentinal tubular in primary molars were lower than the values reported for permanent teeth and may account for the lower permeability of the primary molars.