Light cured resin composites have been widely used in dentistry and biocompatibility of the material has been studied. A lot of studies issued the cytotoxic effect of their components. However there is little information about the cytotoxic effect of radicals to polymerize resin composites. In the present study, we investigated the effect of radicals on the apoptotic pathway to clear the mechanism of cytotoxic effect by radicals.
Method:
Human THP-1 monocytes, 0.5×105 cells/well in 48well-plates, were cultured at 37°Cand 5%CO2 in air. After 0.5mM of dimethyl-aminoethyl methacrylate and 0.4mM of camphour quinone were added, the THP-1 cells were irradiated for 40 sec by light irradiation unit utilizing to cure resin composites. The concentrations of these chemicals added have been previously shown to be subtoxic to THP-1 cells. Then activities of Caspase 3/7, Caspase 8, or Caspase 9 were measured at 1, 6, or 24h (n=8). These enzymes are activated when apoptosis is induced. The activity was revealed as relative activities to the control group that no chemicals added without light irradiation at 1h.
The data were statistically analyzed by one-way ANOVA and Dunnett’s test (a<0.05)
Result:
For Caspase3/7, the activities were significantly increased at 1, 6, and 24h. The activity at 6h showed 850% to the control group.
For Caspase8 or 9, the activities were significantly decreased by 20-50% to the control group.
Conclusion:
The results suggested that radicals induced apoptosis in THP-1. However, the pathway of the apoptosis might not depend on mitochondrial pathway or death-ligand pathway. There is a possibility to participate other apoptotic pathways.