| The objective for this project is to develop a bioactive dental composite showing enhanced mechanical properties through the development of a designed interface and to experimentally evaluate and model these interfaces. The efficiency of the surface modifications is analyzed as it relates to the bioactivity of the filler, a sol-gel derived bioglass (60 mol% SiO2, 36 mol% CaO, 4 mol% P2O5), and to the enhancement of mechanical properties. Among the filler surfaces studied are a methacryloxypropyl triethoxysilane (MAMTES) coupling agent combined with a methyl triethoxysilane (MTES) coupling agent, and a grafted sulfonated polysulfone (SPSF) with different degrees of sulfonation.; The resin system chosen is based on 2,2′-bis-(4-methacryloylethoxyphenyl) propane using triethylene glycol dimethacrylate as a diluent to improve processability. To help offset the polymerization shrinkage, nadic methyl anhydride is added Hydrolysis of this anhydride provides a mechanism for offsetting shrinkage.; A dependence on the ratio of methacrylate functionalized coupling agent on the reinforcing capabilities of the filler was discovered. This dependence also translates into the stabilization of the interface after a solution soak. Enhanced properties at mid-level ratios of MAMTES to MTES show the importance of the coupling system and not just the presence of a coupling agent to the enhancement of a composite. Evidence of the bioactivity of the composites is seen in a comparison of composite samples after submersion in either pure water or a salt solution. Additional weight gain could be the result of the sorption of HCA forming ions (calcium and phosphate) from the salt solution. The lower weight gain rate for the silanated composite supports a shielding effect of the coupling agent to the bioactivity of the filler.; Sulfonated polysulfones were successfully prepared and grafted onto the Bioglass® filler. A dependence on the level of sulfonation on the reinforcing capabilities of the filler was discovered. At higher degrees of sulfonation there is an increased water attraction at the interface that leads to a higher propensity for hydrolytic degradation and lowered mechanical properties. Along with the lowered mechanical properties, however, there is evidence of HCA growth that is necessary for the condition of bioactivity. |
