REDUCTION OF POLYMERIZATION SHRINKAGE AND STRESS

拟议研究的长期目标是开发方法， 测量和抵消树脂基材料中产生的应力 由于聚合收缩。 具体目标是：（一）建立一个 张力计，用于测量聚合过程中产生的应力 树脂基材料;（ii）研究潜在的松弛 树脂和复合材料中的聚合应力。 本文介绍了一种测量收缩应力的装置， 由Feilzer等人设计，（1993年）。慢速和快速固化复合体系 随着填料量的增加，将用于测试一种可能的 应力与收缩的相关性及评价仪器 再现性 将化学计量量的化合物加入到 以补偿固化收缩。 如果这些金额将 如果不将应力降低到零，化合物浓度将增加到 进一步减轻压力。 限量将根据 反应物浓度对其它物理性质的影响 复合材料（例如，固化度，径向拉伸强度，4点 横向测试（TS）、对牙本质的粘附性、吸水性和溶解性）。 为了保持较高的物理性能，TS降低15%以上 会被认为是不可接受的 具体目标中确定的系统 作为降低聚合引起的收缩的候选体系， 牙科复合材料中的应力将在最终随机侧中进行比较， 并行实验设计，包括对照。 虽然压力 减少将是关注的主要响应变量，收缩， 固化度、吸水性、横向强度、吸水性和溶解性 所有这些都将在最终推荐一个有用的系统时加以考虑。

The long-term goal of the proposed research is to develop methods to measure and counteract the stresses developed in resin-based materials due to polymerization shrinkage. The specific aims are: (i) to build a tensometer for measuring stresses developed during the polymerization of resin-based materials; (ii) to investigate the potential relaxation of polymerization stresses in resins and composites. An apparatus for measuring shrinkage stresses will be built following a design by Feilzer et al., (1993). Slow and fast curing composite systems with increasing amounts of fillers, will be used to test a possible correlation between stress and shrinkage and to evaluate instrument reproducibility. Stoichiometric amounts of compounds will be added to composites to compensate for curing contraction. If these amounts will not reduce stress to zero, compound concentrations will be increased to further reduce stress. The limiting amounts will be determined from the effects of the reactant concentrations on other physical properties of the composite (e.g., degree of cure, diametral tensile strength, 4-point transverse test (TS), adhesion to dentin, water sorption and solubility). To maintain high physical properties, a decrease in TS of more than 15% would be considered unacceptable. Systems identified in Specific Aims as candidate systems for reducing polymerization-induced shrinkage and stress in dental composites will be compared in a final randomized side- by-side experimental design including controls. Although stress reduction will be the primary response variable of interest, shrinkage, degree of cure, DTS, transverse strength, water sorption and solubility will all be considered in the final recommendation of a useful system.