Nanoindentation study on mechanical properties and curing depth of dental resin nanocomposites

Mechanical properties and curing depth of bisphenol‐α‐glycidyl methacrylate/triethylene glycol dimethacrylate‐based dental composites were systematically investigated by site‐specific nanoindentation tests. Effects of filler (20‐nm silica nanoparticle) content on the nanohardness and elastic modulus of the composites were studied in comparison with micromechanics theoretical models. Results showed that the incorporation of the silica nanoparticles at low contents (up to 5.66 vol%) significantly increases the hardness and elastic modulus of the dental composites by up to 65% and 30%, respectively. It was found that the Counto model gave good predictions for the composite modulus as a function of filler content. For the specific composites studied here, the depth of cure increases approximately linearly with the filler content, which may be ascribed to the stronger reinforcement effect of the silica nanoparticles on the dental composites at a higher particle content. These results combined demonstrate the effectiveness of silica nanoparticles as the reinforcement for dental restorative materials even at small volume fractions. POLYM. COMPOS., 40:1473–1480, 2019. © 2018 Society of Plastics Engineers