EFFECTS OF METHACRYLATES PRESENT IN COMPOSITE RESINS ON REDOX STATUS OF HUMAN PULP CELLS

Background: Composite resins, utilized in dentistry, are complex mixed materials composed also by methacrylic monomers like triethylenglycol-dimethacrylate (TEGDMA) and 2-hydroxyhethyl methacrylate (HEMA). Since the polymerization reaction of monomers is uncomplete the release of these compounds may implement adverse effects in the organism. To understand the causes of this toxic action, the effects of TEGDMA and HEMA on cellular redox status were investigated in this study. The analytical techniques utilized are usually applied in Clinical Biochemistry in patient’ s serum for the evaluation o oxidative stress. Methods: Pulpal Cells were used in this study. Sub-cytotoxic concentrations of monomers were identified by the MTT assay and the following parameters were analysed: 1) Production of reactive oxygen species (ROS), measured using the probe 2’,7’-dichlorodihydrofluorescin diacetate by a Glomax Multi detection system fluorimeter (Promega, Milan, Italy) (490 nm excitation and 526 nm emission wavelengths). 2) Reduced Glutathione (GSH) and Total Glutathione (GSH+GSSG), determined by Ellman method. 3) GSH metabolism, investigated through the assay of glutathione reductase (GR) and glucose-6-phosphate dehydrogenase (G6PDH) activity. NADPH absorbance modifications at 340 nm were used to determine the activity of both enzymes. 4) Superoxide dismutase (SOD) and Catalase enzymatic activities, were measured (Packard Spectracount; Packard BioScience) using the appropriate SOD determination kit (19160 Fluka Analytical, Sigma-Aldrich, Milan - Italy) and Catalase Assay kit (SigmaAldrich, Milan - Italy) Statistical analysis Data are expressed as the mean ± statistical error of the mean (SEM) and compared by analysis of variance (ANOVA), P <0.05 was considered significant. Results: Monomers induced an increase (about 100%, P <0.01) of ROS production with a consequent increase of SOD (about 10% P <0.05) and catalase enzymatic activity (about 30% P <0.05). Moreover, monomers provoked a depletion both of GSH and GSH+GSSG (40% P <0.01), no changes in GR and G6PDH activity were observed. Conclusions: These changes can then be considered as a mechanism able to trigger clinical and sub-clinical adverse effects, thus calling for further investigation on biocompatibility of dental materials