Development of a risk assessment method for dental materials using a bone metabolic system

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Many chemicals released into the environment are believed to disrupt normal endocrine functions in humans and anima1s. These endocrine-disrupting chemicals (EDCs) affect reproductive health and development. Currently, attention is focused on the development of in vivo and in vitro screening strategies to identify and classify EDCs, in order to determine whether such chemicals pose a hazard to human health. In previous studies, we reported on the estrogenic activity of compounds, receptor-binding assays, and receptor gene expression assays using cultured cells and yeast cells, and a yeast two-hybrid assay. These screening tests were applied to the risk evaluation of dental materials. Despite the usefulness of these methods for detecting estrogenicity, they have their limitations. In particular, very little is known about whether EDCs affect bone formation. This study investigated the effects of the genotoxicity and estrogenicity of dental materials. It is hoped that a bioassay of EDCs and genotoxic chemicals in vivo can be established, using osteoblasts, and then applied, to judge the safety of the chemicals that leach from dental materials in the mouth. Summarizing the results of the various analyses carried out in these studies, the following conclusions were drawn:1) Chemicals such as resin monomers and plasticizers leach out of dental resins after polymerization.2) Some components of dental materials have genotoxic or estrogenic activity.3) Measurements of RANKL, OPG, ERα, and ERβ mRNA in osteoblasts exposed to chemicals were useful for evaluating risk assessment in a bone metabolic system.