Effects of monomers eluted from dental resin restoratives on osteoblast-like cells

Resin-modified glass-ionomer (RMGIC) has been demonstrated to exhibit inhibition on the growth and differentiation of osteoblasts on its surface. In this study, the hypothesis that the different levels of inhibitory effects on osteoblasts of resin restoratives depend on elution of unpolymerized monomers was examined. Release of monomers from cured specimens of Bis-GMA/TEGDMA-composites, MMA-resin cements, or HEMA-containing RMGIC was determined and osteoblast-like MC3T3-E1 cells were cultured in the presence of 100-10 microg/mL of TEGDMA, 10-1 microg/mL of MMA, or 400-50 microg/mL of HEMA according to the release concentrations. Cell proliferation, alkaline phosphatase (ALP) activity, the expression of osteoblastic markers, and mineralized tissue formation were evaluated. TEGDMA and MMA at the concentrations tested did not affect the growth of MC3T3-E1 and exhibited little harmful effects on their differentiation and mineralization. On the contrary, HEMA inhibited proliferation, ALP activities, the expression of osteocalcin, and mineralized tissue formation at 200 microg/mL or more. These results indicate that HEMA at the concentrations similar to that observed in elution tests affected osteoblastic proliferation, differentiation, and mineralization, suggesting that elution of unreacted HEMA could be the main component of the adverse effects of RMGIC on osteoblast-like cells and influences of resin restoratives on the osteoblasts are possibly dependant on release characteristics of unpolymerized monomers.