The nanofiller effect on properties of experimental graphene dental nanocomposites

Abstract

The purpose of the present study is to analyze the effect of the new nanofiller type graphene–gold nanoparticles on the surface structure and surface properties of some dental nanocomposites based on BisGMA/triethyleneglicol dimethacrylate matrix. Materials used in our study were three experimental nanocomposites, two of them based on graphene–gold nanoparticles as filler of different percent. As reference material, a commercial dental nanocomposite product named Herculite XRV Ultra was used. FTIR-ATR spectroscopy was used to determine the residual double bonds and the degree of conversion (DC) after 1 and 21 days of immersion in distilled water at 37 °C. The difference in DC between the experimental materials was statistically analyzed by one tail, paired Student’s t-Tests, using Graph Pod. Surface properties were evaluated through surface free energy using contact angle measurement while roughness and topography was assessed using Atomic Force Microscopy (AFM). To determine the amount of filler particles and thermal behavior of organic matrix, the nanocomposites were investigated by thermal analysis. According to the experimental results, the dental nanocomposites with highest percent in graphene–gold nanoparticles present a better value for the surface free energy. AFM investigations reveal differences in the term of roughness properties and suggest that in order to improve the surface properties is necessary to use a higher percent of graphene–gold nanoparticles as filler. The degradation process of major nanocomposites constituents is observed at temperatures between 240 and 620 °C. Entire results sustain this, but the future studies in order to evaluate the biological properties of the experimental nanocomposites will be made.