In vitro toxicity of spiroorthocarbonate monomers designed for non-shrinking dental restoratives

Biocompatibility of Resin-based Dental Materials

Oral and mucosal adverse reactions to resin-based dental materials have been reported. Numerous studies have examined the biocompatibility of restorative dental materials and their components, and a wide range of test systems for the evaluation of the biological effects of these materials have been developed. This article reviews the biological aspects of resin-based dental materials and discusses the conventional as well as the new techniques used for biocompatibility assessment of dental materials.

Assessment of cytotoxicity and DNA damage exhibited by siloranes and oxiranes in cultured mammalian cells

The potential reactivity and structural properties of oxiranes (epoxides) are advantageous when considering polymers for medical devices. However, epoxy compounds are widely known to have genotoxic properties. The objective of the study was to evaluate the cytotoxicity and primary DNA damage effects induced by oxiranes and siloranes, silicon containing oxiranes. The siloranes, Ph-Sil, Tet-Sil, and Sil-Mix and the oxiranes Cyracure UVR-6105 and 1,3-bis[2-(2-oxiranylmethyl) phenoxy]pentane (OMP-5) were dissolved in organic solvents and dilutions containing less than 0.5% solvent were used in biological assays. The concentration that reduced the viability of 50% (TC(50)) of L929 cells was measured using the MTT assay and guided the selection of subtoxic doses for evaluation of DNA damage. Ph-Sil was more cytotoxic than OMP-5, Cyracure UVR-6105 and Sil-Mix. However, the TC(50) value of Tet-Sil could not be determined due to its poor solubility. DNA damage was evaluated in the sister chromatid exchange (SCE) assay with CHO cells, and the alkaline comet assay with L929 cells. In contrast to the siloranes, the oxiranes exhibited significant increases (p>0.05) in SCE frequencies and DNA migration relative to their solvent controls. Our findings support previous reports that siloranes have low genotoxic potential and can be suitable components for development of biomaterials.

Genotoxicity assessment of oxirane-based dental monomers in mammalian cells

The potential use of oxirane (epoxy) monomers in dental composite development raises the concern to test their genetic safety. Oxiranes can interact with DNA resulting in DNA damage, mutations, and possibly carcinogenesis. Our objective was to evaluate DNA damage and cell-cycle disruption in mammalian cells after exposure to epoxy monomers. The experimental oxiranes were Araldite trade mark GY 281, Cyracure trade mark UVR 6105 and 1,3-dioxane-2,2'-1,3-dioxane-5',4'-bicyclo[4.1.0] heptane (DECHE-TOSU). L929 fibroblast cells were incubated with the monomer for 7 and 24 h at 37 degrees C/5% CO(2). After incubation, cells were subjected to DNA damage alkaline unwinding assay and flow cytometry cell-cycle analysis. Lack of DNA damage and cell-cycle effects were observed with DECHE-TOSU. Exposure to subtoxic doses of Araldite trade mark GY 281 or Cyracure trade mark UVR 6105 caused DNA damage and cell cycle disruption. A significant (p < 0.01) effect for Araldite trade mark GY 281 was observed with cell populations in G1 and G2/M when compared to DMSO solvent control. Similar comparisons revealed significant differences in G2/M cell cycle population after 24-h exposure to 100 microM Cyracure trade mark UVR 6105. For comparison, BISGMA was evaluated to produce DNA damage but without cell-cycle effects suggesting DNA repair mechanisms were effective. Our findings with DECHE-TOSU, Araldite trade mark GY 281 and Cyracure trade mark UVR 6105 indicated cell-cycle disruption followed DNA damage.