Cytotoxic and nongenotoxic effects of phenolic compounds in human pulp cell cultures

Phenolic compounds are widely used in clinical dentistry as sedatives for t he dental pulp, as disinfectants for caries, and as root canal medications. The pathobiological effects of various phenolic compounds on human dental pulp fibroblasts were investigated with Hoechst 33258 fluorescence assay an d DNA precipitation assay. All phenolic compounds showed cytotoxicity in Ho echst 33258 fluorescence assay by inhibiting cellular DNA in a concentratio n-dependent manner. The 50% inhibition concentrations required to decrease the cellular DNA contents by guaiacol, phenol, eugenol, and thymol were 9.8 , 4.5, 0.9, and 0.5 mM, respectively. However these phenolic compounds did not cause DNA single-strand breaks in cultured human pulp fibroblasts. Thes e results indicate that phenolic compounds are cytotoxic agents but are wit hout genotoxic effects on human pulp fibroblasts in vitro. However care sho uld be taken to reduce the possibility of pulpal as well as periapical irri tations from inadvertent extrusion of these substances in clinical usage.