A surface pre-reacted glass-ionomer (S-PRG) fillers have been used for incorporation into a variety of dental materials. Owing to their diverse applications, it is important to evaluate their biological safety under various test conditions. This study evaluated the cytotoxic effect of exposure to various concentrations of S-PRG fillers or their eluates in RAW264 cells employing cytotoxic assays and morphological observation using a transmission electron microscope. No cytotoxic effects were

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... d in the presence of the eluates under all concentrations tested, whereas the direct exposure of higher concentrations of S-PRG fillers to RAW264 cells showed cytotoxicity. By microscopic observations, S-PRG fillers or their depositions were found in the cells or nuclei. These findings indicated that the eluates from the S-PRG fillers exerted no influence on cytotoxicity of the RAW264 cells. Although the direct exposure of the S-PRG fillers to the cells resulted in cytotoxicity due to endocytosis, filler eluates possessed no cytotoxicity. Thus, cytotoxicity of the S-PRG fillers depends on the conditions of the exposed fillers.