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

描述（由申请人提供）：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。其他缺点涉及缺乏韧性、热膨胀失配、聚合后的水分吸收、固化后的可提取的未反应单体和氧抑制。收缩引起的应力主要与甲基丙烯酸酯基自由基聚合过程的链增长性质相关，其导致高体积收缩和早期凝胶化。通过降低反应性甲基丙烯酸酯官能团的浓度或延迟聚合期间的凝胶化来减轻收缩应力。我们提出了一个激进的转变的聚合机理从链增长聚合的混合模式的逐步链增长聚合。这种转变是通过引入硫醇-烯组分作为反应性稀释剂来实现的，其具有两个明显的优点。硫醇-烯聚合机理导致较低的体积收缩和延迟的凝胶化。此外，我们提出了控制结构和尺寸的分子填料的掺入。适当地制造、设计和引入分子填料将降低反应性基团的浓度，并增加填料负载超过现有水平，具有相应的机械性能和收缩益处。由于反应性官能团被结合在整个分子填料中而不是仅在表面处，因此分子填料将在聚合之前更好地整合，这防止了聚集，并且在聚合之后更好地整合，这改善了韧性和其它机械性能。将这两种发展协同结合成复合系统将导致复合系统表现出显著降低的收缩和应力以及改善的机械性能。这些目标是基于这样的假设，即适当的材料合成和设计加上聚合机制的优化将导致增强的聚合物牙科复合材料的收缩应力，复合材料的机械性能，聚合速度（或减少引发剂含量），水分吸收，减少可提取物和改善的生物相容性。迄今为止的结果已经证明了较高的双键转化率、较低的体积收缩诱导应力、改善的机械性能和几乎消除的氧抑制。 公共卫生相关性：由于美学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公众的口腔健康产生非常广泛和积极的影响。迄今为止，这些材料的改进是由填料相的改性驱动的，其中本申请通过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.