Possible Oxidative Pathways of Dental Composites Cytotoxicity:  In Vitro Study

Objective: Dental composites (DCs) commonly consist of a mixture of monomers, such as BisGMA (bisphenol-A-diglycidyl-dimethacrylate) or UDMA (urethane-dimethacrylate) in combination with co-monomers of lower viscosity (TEGDMA -triethylene-glycol-dimethacrylate), filler particles and silane component. DCs have shown to produce local, as well as, certain systemic toxic effects, based on in vivo experimental studies. Oxidative stress (OS) was established to contribute to DCs′ cytotoxicity, leading to apoptosis (programed cell death). In altered functioning of mitochondria, seen in OS, transmembrane migration of phospholipide cardiolipin occurs, leading to formation of complex with cytochrome c (cyt c). Formed complex show immense peroxidase activity, a possible triggering mechanism of apoptosis. Effect of DCs and lipophilic antioxidant d-tocopherol (d-TOC), applied concomitantly, on peroxidase activity of cyt c/cardiolipin complex was tested in vitro.

Method: Measurement of cyt c/cardiolipin peroxidase activity was determined fluorometrically by Amplex Red method.

Result: The obtained results have shown that examined DCs reduce/or have no effect on the peroxidase activity of cyt c/cardiolipin complex in vitro, implying that some other cell signaling triggering pathways are involved in achievement of apoptotic program, if any.

Conclusion: DCs and d-TOC present in combination, reduce peroxidase activity of cyt c/cardiolipin complex, synergistically, in dose dependent manner.