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

纳米聚集体改善收缩应力

• 批准号: 7454152
• 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 2010-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7454152
• 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; Object Attachment; Organic solvent product; Phase; Plant Resins; Plasticizers; Polymers; Preparation; Process; Property; Reaction; Research; Rubber; Silanes; Silicon Dioxide; Stress; Structure; Surface; System; Technology; Testing; Time; Today; 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; size

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）：市售牙科复合树脂在聚合过程中表现出2-5%体积收缩的固有问题。这种聚合会在复合材料修复体中产生收缩应力，从而破坏复合材料和牙齿结构之间的边缘密封。尽管开发了新的牙本质粘合剂，但由于不可避免的聚合收缩应力，目前没有系统能够承受牙齿/修复体界面处间隙的形成。 此外，现有的复合树脂韧性较低，导致复合修复体出现边缘和整体断裂。 我们在这里描述了一种减少收缩应力并提高复合树脂韧性的新方法，该方法只需对现有技术进行两次修改。第一种方法中，柔顺相材料（例如聚丁二烯）与气相二氧化硅以聚集体形式取代了增强填料。这些均匀分散的柔顺聚集体在聚合过程中产生的静水拉伸应力状态下屈服，并允许聚集体膨胀或柔顺，从而抵消固化收缩并减少粘合界面处的应力。 第二种改性是在基体单体中引入少量增塑剂。增塑剂可降低固化过程中的玻璃化转变温度 (Tg)，从而在交联和扩链反应过程中链活动性在较长时间内保持较高水平，从而在单体转化为聚合物的过程中实现更大程度的固化收缩补偿和收缩应力降低。 我们表明，微米级柔顺聚集体的存在会导致弯曲模量、弯曲强度和断裂能增加，并且微米级聚集体与增塑剂的结合会导致聚合收缩应力降低。此外，我们还发现，纳米级聚集体对树脂基体具有非常大的柔顺表面积，可以成比例地增加聚合收缩应力的降低。 总体而言，顺应性骨料有可能克服当今美学和后部树脂的两个主要问题，即有问题的收缩应力和低韧性。作为对市售复合树脂的改性，顺应性骨料有可能提供卓越的复合修复系统。