A comparison of dental restorative materials and mineralized dental tissues for surface nanomechanical properties

Restorations are commonly used to replace the lost or damaged tooth tissues. The aim of this research was to evaluate the surface mechanical properties (hardness and elastic moduli) of mineralized dental tissues. In addition, hardness and elastic moduli of various restorative dental materials have been reported. Freshly extracted maxillary premolars and seven restorative materials were included in the study. All samples were characterized for nanomechanical properties. A minimum of five nanoindentations were performed using Hysitron [TI 725 Ubi] testing instrument. Data was analyzed using the SPSS software (version 20) and t-test was applied measuring the statistical significance. The tooth enamel hardness range was 2.23 to 7.18 GPa being the hardest at cusp tip (absolute hardness of 6.44±0.74). The bulk of dentin exhibited hardness of 0.71 to 0.92 GPa. Porcelain was the hardest material (9.49±0.52 GPa) followed by Co-Cr and Ni-Cr alloys. Poly methyl methacrylate has the lowest hardness (0.18±0.02 GPa) improved hardness for GIC (0.34±0.05 GPa) resin composites (0.54±0.07 GPa) and amalgam (2.55±0.30 GPa). The dental tissues and materials have a wide range of hardness and elastic modulus. The choice of Biomaterials point of view, a single material cannot be used for all mineralized tissues. Clinically, each case (restoration) should be considered on individual bases to evaluate the material of choice.