Bioactive components of dental resins interact with adjacent cells, producing effects ranging from acute to chronic cytotoxicity, depending upon the components' physico-chemical properties and the cell type. Objectives: Since many cellular responses to resin components are a result of their interactions with the cell membrane, several resin components were compared for cytotoxicity relative to their hydrophobicity. Methods:The components selected were the DMABEE (4-dimethylaminobenzoic acid), DMDDA (dimethyldodecane amine), DMTDA (N,N-dimenthytetradecyl amine), DMAEMA, (dimethylaminoethyl methacrylate), HEMA (hydroxyethyl methacrylate), and the hydrogenated derivitives H-DMAEMA and H-HEMA. Cultured hamster epithelial cells were plated, then exposed to serial dilutions of the resin components. After 24 hr incubation at 37°C in 95%air/5%CO₂ cytotoxicity was assessed by the MTS assay. Responses of the cells were compared to solvent controls by ANOVA. The values presented are the lowest concentrations that demonstrated significant differences from control cultures (p<0.05). Values in parentheses are the Hoy's solubility parameters. Results: The toxic levels were as follows: DMDDA (17.2)=0.01 mM; DMTDA (17.5)=0.5 mM; DMABEE (18.7)=1.0 mM; DMAEMA (18.7)=32 mM; H-DMAEMA (18.2)=64 mM; HEMA (24.9)=10 mM; and H-HEMA (24.3)=100 mM. Conclusions: Results suggest that the components with a lower Hoy's parameter (greater hydrophobicity) are more cytotoxic, although presence of a methacrylate group mitigates this. Hydrolysis of HEMA and DMAEMA by esterases may be a rate-limiting step that affects cytotoxicity by these components. The hydrogenated derivatives may be hydrolyzed more slowly than the non-hydrogenated forms, hence their lesser toxicities. Thus, cytotoxicity may relate to a material's solubility and rate of hydrolysis, that may in turn affect its interactions with the cell membrane. Supported by RO1-DE -11980

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