Development of Novel Thiol-Ene-Methacrylate Composites for Dental Restorative Mat

描述(申请人提供)：聚合物复合牙科修复材料的性能和寿命仍然有限，主要是由于收缩引起的聚合应力引起的并发症。其他缺点包括缺乏韧性、热膨胀不匹配、聚合后吸湿、可提取、固化后未反应的单体以及氧气抑制。收缩引起的应力主要与以甲基丙烯酸酯为基础的自由基聚合过程的链增长性质有关，该过程导致高体积收缩和早期凝胶。通过降低反应性甲基丙烯酸酯官能团的浓度或延缓聚合过程中的凝胶化，可以缓解收缩应力。我们提出了聚合机理的激进转变，从链生长聚合到混合模式的分步链生长聚合。这种转变是通过加入硫醇-烯成分作为活性稀释剂来实现的，这有两个明显的优点。硫醇-烯烃聚合机理导致较低的体积收缩和延迟胶凝。此外，我们还建议加入结构和大小可控的分子填料。适当的制备、设计和掺入分子填料将降低反应性基团的浓度，并使填料的加入量超过目前的水平，并具有相应的力学性能和收缩效益。由于反应性官能团被结合到整个分子填料中，而不是仅在表面，因此分子填料在聚合前和聚合后将更好地整合在一起，从而防止聚集，从而提高韧性和其他机械性能。将这两项发展协同结合到一个复合体系中，将导致复合体系表现出显著减少的收缩和应力，并改善机械性能。这些目标是基于这样一个假设，即适当的材料合成和设计加上聚合机理的优化将导致在收缩应力、复合材料力学性能、聚合速度(或引发剂含量的降低)、吸湿率、减少可萃取物和改善生物相容性方面提高聚合物牙科复合材料的性能。到目前为止，结果已经显示出更高的双键转化率，更低的体积收缩引起的应力，更好的机械性能，以及几乎消除氧抑制。 公共卫生相关性：由于美容复合牙科修复材料的广泛使用，其可靠性和性能的显著改善将对普通公众的口腔健康产生非常广泛和积极的影响。到目前为止，这些材料的改进是由填充阶段的改进推动的，在该阶段，该应用通过一种新的化学方法解决了聚合物相的持续缺陷。

DESCRIPTION (provided by applicant): The performance and longevity of polymer composite dental restorative materials is still limited, primarily due to complications from shrinkage induced polymerization stresses. Other drawbacks involve a lack of toughness, thermal expansion mismatch, moisture uptake following polymerization, extractable, unreacted monomer following cure, and oxygen inhibition. Shrinkage induced stresses are primarily associated with the chain growth nature of the methacrylate-based free radical polymerization process that leads to high volume shrinkage and early gelation. Shrinkage stress is alleviated either by reducing the concentration of reactive methacrylate functional groups or delaying gelation during polymerization. We propose a radical shift in the polymerization mechanism from a chain growth polymerization to a mixed mode step-chain growth polymerization. This shift is achieved by the incorporation of a thiol-ene component as the reactive diluent, which has two distinct advantages. The thiol-ene polymerization mechanism results in lower volume shrinkage and delayed gelation. Additionally, we propose the incorporation of molecular fillers of controlled architecture and size. Appropriately fabricating, designing and incorporating molecular fillers will reduce the concentration of reactive groups and increase the filler loading beyond the present levels with corresponding mechanical property and shrinkage benefits. Since the reactive functionality is incorporated throughout the molecular filler rather than only at the surface, the molecular filler will be better integrated before polymerization, which prevents aggregation, and following polymerization, which improves toughness and other mechanical properties. Synergistically combining these two developments into a composite system will result in composite systems that exhibit both dramatically reduced shrinkage and stress and improved mechanical properties. These aims are predicated on the hypothesis that appropriate materials synthesis and design coupled with optimization of the polymerization mechanism will lead to enhanced polymeric dental composites with respect to shrinkage stress, composite mechanical properties, polymerization speed (or reduction in the initiator content), moisture uptake, reduced extractables and improved biocompatibility. Results to date have already demonstrated a higher double bond conversion, lower volume shrinkage induced stress, improved mechanical properties, and near elimination of oxygen inhibition. PUBLIC HEALTH RELEVANCE: Because of the widespread use of esthetic composite dental restorative materials, significant improvements in their reliability and performance will have a very broad and positive effect on the oral health of the general public. Improvements in these materials to date have been driven by modifications in the filler phase where this application addresses the continuing deficiencies of the polymer phase through a novel chemistry approach.