|Budget Amount *help
¥3,200,000 (Direct Cost : ¥3,200,000)
Fiscal Year 1999 : ¥1,000,000 (Direct Cost : ¥1,000,000)
Fiscal Year 1998 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1997 : ¥1,400,000 (Direct Cost : ¥1,400,000)
Acrylic resins are widely used as dental materials. There have several reports concerning the amount of residual methyl methacylate(MMA), triethylene glycol dimethacrylate(TEGDMA) and so on, which are one of the principal factors that have an effect on the properties of dental materials and will be responsible for oral mucosa inflammatory symptoms and systemic ones. Thus, the levels of residual MMA, TEGDMA and so on in dental resins have become very important from the point of view of the quality of dental resins and the clinical problems. While there have been some reports regarding the levels of residual MMA,TEGDMA and Bis-GMA in dental resins, little is known of reports concerning quantitative analysis of all components leached from dental resins. The purpose of the present study was to develop a new determination method for leachable components from dental resins using HPLC together with verification of its accuracy and also to determine the levels of components leached from dental
resins that were immersed in 100% methanol, 5-100% ethanol and distilled water and to develop a new method for toxicity testing using the change in the value of fluorescence anisotropy(γ) which is the index of membrane fluidity.
For good separations of leachable components, a mixture of 50% acetonitrile+50% 10mM phosphate buffer (pH2.5) in acrylic resins and 44%acetonitrile+56%distilled water in fissure sealants and a polymer-coated CィイD218ィエD2 column were required. Leaching of components from dental resins could occur in different amounts and different rates, depending on kinds of solvents. By the immersion in methanol(or ethanol), benzoic acid(BA), MMA, methyl benzoate(ethyl benzoate in ethanol) and benzoyl peroxide were leached from acrylic resin plates and by the immersion in distilled water, only MMA and BA were leached from plates. In addition , infissure sealants, TEGDMA, Bis-GMA and so on were detected by the immersion of methanol, whereas, by the immersion in artificial saliva, a main leachable component was TEGDMA.
As MMA, TEGDMA, ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butane diol dimethacrylate, trimethylolpropane trimethacrylate, Bis-GMA and UDMA decreased γ values concentration-dependently in cells derived from human periodontal ligament, suggesting that these monomers increase membrane fluidity, an correlation between the changes in γ values which are the index of membrane fluidity by these monomer sand the toxicity potency in neutral red assay and MTT assay were examined. A good correlation was found between these two different methods and γ values.
These results suggest that toxicity testing using membrane fluidity is a highly useful and excellent method. Less