Study On Modification Of Dental Visible Light Cured Composites

The dental restorative composites for repairing the tooth defect caused by saprodontia and trauma can be divided into three classes:baked porcelain, alloy materials and polymeric composites. The polymeric composites has been widely used because of the convenient handling, flexible selection of the color and good performance of the curing product.The visible cured composites is composed of resin matrix, processed inorganic fillers and initiating system. To improve the comprehensive performance of polymeric composites, this paper mainly modified the resin matrix and inorganic fillers. In the chapter two, we processed the fluorinated modification on the frequently used resin, which is bisphenol A glycidyl dimethacrylate (Bis-GMA) which has many advantages, also many shortcomings which can’t be ignored, such as the large viscosity, high hydroscopicity and the double bond conversion is not high. To overcome these shortcomings, we have modified the two hydroxyl of Bis-GMA into fluoric chains. At the same time, we have designed different dosages of raw materials, reaction temperature and reaction time, through the FTIR spectrum, we obtained the optimized reaction conditions. Through the FTIR and NMR spectrum, we proved that the product Bis-F-GMA has the designed structure. Compared with Bis-GMA, Bis-F-GMA has less viscosity, high conversion rate, little volume shrinkage and hydrohobicity. The composites composed with Bis-F-GMA also has many advantages, such as low hydroscopicity and solubility, high bending strength and elasticity, good biocompatibility.In chapter three, we synthesized the gradient polymethyl methacrylate (PMMA) particles by photopolymerization which have excellent binding force with resin matrix, solved the problem of weak binding between inorganic fillers and resin matrix. The diameter of the synthesed particles are1～2μm, also uniformly dispersed. Using these gradient PMMA particles as fillers for dental restorative composites has some influence on the properties of composites, slightly changed the curing conversion of double bond and dynamic mechanics performance, increased the water absorbing quality and solubility, reduced the flexural strength, largely reduced the volume shrinkage and has good biocompatibility.