The Nanomechanical and Tribological Properties of Restorative Dental Composites after Exposure in Different Types of Media

The aim of this study was to evaluate the effects of various acidic solutions on the surface mechanical properties of commercial resin composites with different microstructures (Filtek Z350 XT, TPH3, Durafill, and Superlux). Specimens were immersed in orange juice, cola, and distilled water for 5 days and the nanohardness, elastic modulus, and wear behavior of the samples were determined via the nanoindentation test and a reciprocating nanoscratch test. The nanoscratch morphology was observed using scanning electron microscopy (SEM) and the wear depth was recorded by scanning probe microscopy (SPM). The results indicate that the nanofilled resin composites had the greatest hardest and highest elastic modulus, whereas the microfilled composites exhibited the lowest nanohardness and elastic modulus values. SEM observations showed that all resin composites underwent erosion and surface degradation after immersion in acidic solutions. Furthermore, the wear resistance was influenced by the composition of the acidic solution and was correlated with the nanohardness and elastic modulus. The dominant wear mechanism changed from plastic deformation to delamination after immersion in acidic solutions