Comparison of nanohardness between coronal and radicular intertubular dentin.

This study investigated the hardness and Young's modulus of coronal and radicular intertubular dentin. Ten bovine teeth were each divided into coronal and radicular groups, and the flat surfaces of the coronal and radicular dentin were subsequently processed along the tooth axis. The hardness and Young's modulus of the coronal and radicular intertubular dentin were evaluated using nanoindentation tests, at two locations per tooth. Mean hardness and Young's modulus values were statistically compared by one-way ANOVA and Fisher's PLSD test. The hardness of coronal intertubular dentin was 0.81 +/- 0.05 GPa and that of radicular dentin was 0.55 +/- 0.02 GPa. Additionally, the Young's modulus of coronal intertubular dentin was 26.60 +/- 2.19 GPa and that of radicular dentin was 20.89 +/- 1.10 GPa. Findings of this study revealed that the hardness and Young's modulus of coronal intertubular dentin were greater than those of radicular intertubular dentin.