Oxidative stress and cytotoxicity generated by dental composites in human pulp cells

Dental composites are a source of residual monomers that are released into the oral environment. Since monomers act on cultured cells through reactive oxygen species (ROS), we hypothesized that composites generate ROS associated with cytotoxicity. Human pulp-derived cells were exposed to extracts of methacrylate-based materials including triethylene glycol dimethacrylate and 2-hydroxyethyl methacrylate-free composites (Tetric Ceram, Tetric EvoCeram, els, els flow, Solitaire 2) and a silorane-based composite (Hermes III). The materials were polymerized in the presence and absence of a polyester film and then extracted in culture medium. The generation of ROS was measured by flow cytometry, and cytotoxicity was determined as well. Methacrylate-based composites reduced cell survival but varied in efficiency. Undiluted extracts of Solitaire 2 specimens prepared in the absence of a polyester film reduced cell survival to 26% compared with untreated cultures. Cytotoxicity was reduced when specimens were covered with a polyester film during preparation. Cytotoxicity of the composites was ranked as follows: Solitaire 2 >> els flow > Tetric Ceram = Tetric EvoCeram = els > Hermes III. The generation of ROS followed the same pattern as detected with cytotoxic effects. A positive correlation was found between ROS production and cell survival caused by extracts made from materials not covered with a polyester film. These findings suggest that components released from composites affect cellular signaling networks through ROS formation. Regenerative and reparative capacities of the dentine-pulp complex may be impaired by biologically active resin monomers released from composite restorations.