Nano-aggregates Improve Contraction Stress & Toughness in Dental Composite Resins

纳米聚集体改善收缩应力

• 批准号: 7643309
• 负责人: VALERIE A LEE
• 金额: $ 23.25万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7643309
• 关键词: Acrylonitrile; Address; Adsorption; Area; Butadiene; Composite Dental Resin; Composite Resins; Coupling; Dental; Dentin; Dentin-Bonding Agents; Development; Elastomers; Esthetics; Exhibits; Filler; Fracture; Glass; Mechanics; Methods; Modification; Organic solvent product; Phase; Plant Resins; Plasticizers; Polymers; Preparation; Process; Property; Reaction; Research; Rubber; Silanes; Silicon Dioxide; Stress; Structure; Surface; System; Technology; Testing; Time; Tooth structure; Transition Temperature; Work; composite restoration; crosslink; improved; irradiation; monomer; nano; nanoparticle; nanoscale; nanosized; novel; particle; polybutadiene; polymerization; polymerization shrinkage; prevent; restoration; restorative composite; seal; silane

DESCRIPTION (provided by applicant): Commercially available dental composite resins exhibit the inherent problem of 2-5% volumetric shrinkage during the polymerization process. This polymerization creates contraction stress in the composite restoration, which can disrupt the marginal seal between the composite and the tooth structure. Despite the development of new dentin bonding agents, no system is able to currently withstand the formation of gaps at the tooth/restoration interface, due to unavoidable polymerization contraction stress. In addition, available composite resins suffer from low toughness, which results in marginal and bulk fracture of composite restorations. We describe here a novel means of reducing contraction stress as well as improving toughness in composite resins that entails only two modifications of existing technology. In the first, a compliant phase material, such as polybutadiene, in aggregate form with fumed silica, replaces the reinforcing filler. These homogeneously dispersed, compliant aggregates yield under the hydrostatic tensile stress state generated during polymerization and allow expansion, or compliance, of the aggregates, thereby offsetting cure shrinkage and reducing stress at the bonded interfaces. The second modification is the introduction of a small amount of plasticizer into the matrix monomer. Plasticizers reduce the glass transition temperature (Tg) during curing such that chain mobility remains high for a longer time during the course of the crosslinking and chain extension reaction, and thereby allows greater compliant offset of cure shrinkage and reduction of contraction stress as monomer conversion to polymer progresses. We show that the presence of micrometer-sized compliant aggregates results in increased flexural modulus, flexural strength and energy to break, and that micrometer-sized aggregates in combination with plasticizer result in reduced polymerization contraction stress. In addition, we show that nanometer-sized aggregates, which present a very large compliant surface area to the resin matrix, result in a proportionately increased reduction in polymerization contraction stress. Overall, compliant aggregates have the potential to circumvent two of the major problems of today's esthetic and posterior resins, problematic contraction stress and low toughness. As a modification to commercially available composite resins, compliant aggregates have the potential to provide a superior composite restorative system.

描述（由申请人提供）：在聚合过程中，市售牙科复合树脂表现出2-5％体积收缩的固有问题。这种聚合会在复合恢复中产生收缩应力，这会破坏复合材料和牙齿结构之间的边缘密封。尽管发展了新的牙本质粘结剂，但由于不可避免的聚合收缩应力，目前尚无系统能够承受牙齿/恢复界面处间隙的形成。 此外，可用的复合树脂的韧性低，从而导致复合修复体的边缘和大块骨折。 我们在这里描述了减少收缩应力的新颖手段，并改善了仅需要两种现有技术修改的复合树脂的韧性。首先，用烟雾二氧化硅以综合形式（例如多丁二烯）代替了加固的填充物。这些同质分散的，兼容的聚集体在聚合过程中产生的静静力拉伸应力状态下产生，并允许聚集体的扩展或遵守，从而抵消了治愈的收缩并减少键合接口处的应力。 第二个修饰是将少量增塑剂引入基质单体。增塑剂在固化过程中降低了玻璃过渡温度（TG），从而使链迁移率在交联和链扩展反应过程中持续更长的时间，从而可以更大的合规固化收缩率，并且随着单体转化为聚合物的进展，链接迁移率会更大的稳定性降低和减少收缩应力。 我们表明，符合符合的聚集体的存在导致弯曲模量增加，弯曲强度和能量破裂，并且千分尺骨料与增塑剂结合使用，从而减少了聚合收缩应力。此外，我们表明，纳米尺寸的聚集体对树脂基质呈现非常大的表面积，从而导致聚合收缩应力的减少成比例增加。 总体而言，合规的聚集体有可能规避当今美学和后树脂的主要问题，有问题的收缩应力和低韧性。作为对市售复合树脂的修改，兼容的骨料具有提供优质复合修复系统的潜力。