In vitro cytotoxicity of a composite resin and compomer

Abstract

Aim: This work was designed to investigate the potential cytotoxicity of two of the newer dental restorative materials, Spectrum® composite resin and Dyract® AP compomer. Methodology: Cultured human endothelial cells (ECV-304) were exposed to each of the restorative materials through a 70-μm 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. Results: 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. Conclusions: These results indicate the restorative materials to be potentially toxic, particularly if the degree of light-cure is inadequate.