Influence of aging solutions on wear resistance and hardness of selected resin-based dental composites

Purpose: The purpose of this study was to investigate the effect of different plasticizing aging solutions on wear resistance and hardness of selected universal resin-based dental composites. Methods: Three light cured (one nanofilled, two microhybride) and one hybride chemical cured composites were aged at 37 °C for 48 h in distillated water, ethyl alcohol solution or Listerine mouthwash. After aging the microhardness tests were carried out and then tribological tests were performed in the presence of aging solution at 37 °C. During wear testing coefficients of friction were determined. The maximal vertical loss in micrometers was determined with profilometer. Results: Aging in all liquids resulted in a significant decrease in hardness of the test materials, with the largest values obtained successively in ethanol solution, mouthwash and water. The effect of the liquid was dependent on the particular material, but not the type of material (interpreted as the size of filler used). Introduction of mouthwash instead of water or ethanol solution resulted in a significant reduction in the coefficient of friction. The lowest wear resistance was registered after aging in ethanol and for the chemical cured hybrid composite, but the vertical loss was strongly material dependent. Conclusions: The effect of different aging solution, including commercial mouthrinse, on hardness and wear was material dependent, and cannot be deduced from their category or filler loading. There is no simple correlation between hardness of resin-based dental composites and their wear resistance, but softening of particular composites materials during aging leads to the reduction of its wear resistance.