In vitro cytotoxicity of a composite resin and compomer

This work was designed to investigate the potential cytotoxicity of two of the newer dental restorative materials. Spectrum composite resin and Dyract AP compomer.

Cultured human endothelial cells (ECV-304) were exposed to each of the restorative materials through a 70-microm dentine barrier to simulate the in vivo clinical situation. Cell viability was measured by the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide) assay and lactate dehydrogenase release assay. The effects of different extents of light-curing were also examined by microscopic examination of stained human promyelocytic leukemia cells (HL-60). Caspase-3 activation was determined as a measure of apoptotic cell death.

Assessment of cellular viability indicated that both materials cause cell death, with Spectrum being the more toxic. The cytotoxicity was considerably increased in the absence of the dentine barrier. Direct exposure to Spectrum for 12 h resulted in the death of 69% of the cells after full light-curing (78% of total death was by apoptosis) and 96% after partial light-curing (73% of total death was by necrosis). Assessment of caspase activation, in the absence of the dentine barrier, showed that longer curing-times resulted in an increase in the proportion of the cells dying through apoptosis, rather than necrosis, for both materials tested.

These results indicate the restorative materials to be potentially toxic, particularly if the degree of light-cure is inadequate.