A one-part free radical initiator system to enable visible light-activated polymerization with post-exposure dark cure and extensive, athermal shadow cure behavior

美国每年进行的超过1.6亿次牙科修复治疗中的大部分 涉及树脂粘结复合材料的放置，并认识到很大一部分 牙医的时间要花在修改和更换这些修复体上，显然需要材料 随着临床表现的改善。相对较短的平均临床寿命(约6年)，特别是对于大型 修复，不仅低效和昂贵，而且每一次修复都升级为更具侵入性的治疗。这个 修复体失败率的主要原因是复合体的断裂或丢失，其次是 龋齿。这些问题都可能与修复过程中固化不充分有关，因为 聚合物的性能与粘附牙和相关材料时的转化率有关 受损牙齿的加固也取决于复合树脂的固化程度。未固化 已知的是，从修复体中浸出的单体促进了附近更具侵略性的细菌活动 修复，这进一步强调了良好固化复合材料的必要性。值得注意的是，有显著的 类似商业复合材料的临床使用寿命的差异，这表明 材料的可靠放置具有高度的技术敏感性。这里的目标是设计新颖的光引发 能够传递自由基以进行超越时间和空间足迹的可靠聚合的系统 一种可见的固化光。预期的临床相关应用是用于直接放置维度 厚的、高填充的复合修复材料，其中有大量的光衰减和/或阴影 遇到了图案化。这些重体材料不能容纳在双固化自动混合中 注射器。这一建议的产品可以缓解不完全光固化复合材料的所有担忧 通过开发全新的光活化氧化还原聚合引发系统进行修复 一种版本可以通过采用深色固化过程来增强复合材料未固化区域的初始固化 这种情况在暴露在固化光下后仍会继续。我们的早期结果显示了有限的光聚合 在直接光曝光期间仅达到10%的转化率，然后可以进行无色的完全转换 在随后的暗相中的聚合物。或者，预计另一个版本的启动器将生成完整 在被可见光短暂激活后的转换，即使在没有从 固化光。如果成功，这个示范项目将在光固化方面取得突破， 大大增加了牙科复合材料的固化深度，并提供了完全转化的充分保证 树脂水泥光聚合。除了有保证的完全转换和优化的明显好处 性能，其他优点，如降低聚合应力和改善胶粘剂粘接由于 可以在复合底座上实现更渐进的聚合过程。在这里的成功将代表着 光聚合方面的巨大进展无疑将延伸到牙科以外。

With a majority of the more than 160 million dental restorative treatments performed in the US each year involving the placement of resin-bonded composite materials, and the acknowledgement that a large portion of a dentist’s time is consumed with revising and replacing these restorations, there is a clear need for materials with improved clinical performance. The relatively short average clinical lifespan (~6 years), particularly for large restorations, is not just inefficient and expensive, but each revision escalates to more invasive treatment. The primary reasons for the failure rate of restorations are fracture or loss of the composite as well as secondary caries. These problems are all potentially linked to inadequate curing during placement of the restoration since polymer properties are correlated with degree of conversion while adhesion to the tooth and the associated reinforcement of a compromised tooth are also dependent on the extent of cure of the composite resin. Uncured monomer leaching from a restoration is known to promote more aggressive bacterial activity in the vicinity of a restoration, which further underscores the need for well cured composites. It is notable that there are significant discrepancies in the clinical service life of similar commercial composite materials, which indicates that the reliable placement of the materials is highly technique sensitive. The goal here is to design novel photoinitiating systems capable of delivering free radicals for reliable polymerization beyond the temporal and spatial footprint of a visible curing light. The intended clinically relevant application is for the direct placement of dimensionally thick, highly filled composite restorative materials in which substantial light attenuation and/or shadow patterning is encountered. These heavy-body materials cannot be accommodated in dual-cure auto-mixing syringes. The product of this proposal could alleviate all concern of incompletely photocured composite restorations by development of completely new photo-activated redox polymerization initiation systems that in one version can augment the initial cure in under-cured regions of a composite by engaging a dark curing process that continues beyond exposure to the curing light. Our early results demonstrate limited photopolymerizations reaching only 10% conversion during direct light exposure that can then progress to full conversion of colorless polymer in the ensuing dark phase. Alternatively, another version of the initiator is expected to produce full conversion following a brief activation by visible light even within regions that received no exposure from the curing light. If successful, this demonstration project will introduce a breakthrough in photocuring that would dramatically increase depth of cure and provide full assurance of complete conversion in dental composite and resin cement photopolymerizations. In addition to the obvious benefits of assured full conversion and optimized properties, other advantages such as reduced polymerization stress and improved adhesive bonding due to a more gradual polymerization process at the composite base may be realized. Success here would represent a tremendously important advance in photopolymerization that would undoubtedly extend beyond dentistry.