Potential risks of the use of resin-based restorative materials include direct damage to the pulp cells and the induction of hypersensitivity reactions in patients. In this study, we tested the hypothesis that N-acetyl cysteine (NAC) inhibits resin toxicity and restores the function of pulp cells. Analysis of our data demonstrates toxicity of composite resins on pulp cells in both an in vivo rat and an ex vivo human model system. Moreover, cells that survive after the placement of composites are weaker, and they are induced to undergo cell death when exposed to 2-hydroxyethyl methacrylate (HEMA). The toxic effect of composites on pulp cells is neutralized by NAC. Therefore, NAC protects the cells from damage induced by clinically relevant levels of restorative materials, in both rat and human model systems. The addition of N-acetyl cysteine prior to or concomitant with the application of restorative materials may be beneficial for the health and safety of dental patients.
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