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Dynamic covalent chemistry (DCC) in dental restorative materials: Implementation of a DCC-based adaptive interface (AI) at the resin-filler interface for improved performance.
Dental Materials ( IF 5 ) Pub Date : 2019-12-04 , DOI: 10.1016/j.dental.2019.11.021
Nancy Sowan 1 , Adam Dobson 2 , Maciej Podgorski 3 , Christopher N Bowman 4
Affiliation  

OBJECTIVE Dental restorative composites have been extensively studied with a goal to improve material performance. However, stress induced microcracks from polymerization shrinkage, thermal and other stresses along with the low fracture toughness of methacrylate-based composites remain significant problems. Herein, the study focuses on applying a dynamic covalent chemistry (DCC)-based adaptive interface to conventional BisGMA/TEGDMA (70:30) dental resins by coupling moieties capable of thiol-thioester (TTE) DCC to the resin-filler interface as a means to induce interfacial stress relaxation and promote interfacial healing. METHODS Silica nanoparticles (SNP) are functionalized with TTE-functionalized silanes to covalently bond the interface to the network while simultaneously facilitating relaxation of the filler-matrix interface via DCC. The functionalized particles were incorporated into the otherwise static conventional BisGMA/TEGDMA (70:30) dental resins. The role of interfacial bond exchange to enhance dental composite performance in response to shrinkage and other stresses, flexural modulus and toughness was investigated. Shrinkage stress was monitored with a tensometer coupled with FTIR spectroscopy. Flexural modulus/strength and flexural toughness were characterized in three-point bending on a universal testing machine. RESULTS A reduction of 30% in shrinkage stress was achieved when interfacial TTE bond exchange was activated while not only maintaining but also enhancing mechanical properties of the composite. These enhancements include a 60% increase in Young's modulus, 33% increase in flexural strength and 35% increase in the toughness, relative to composites unable to undergo DCC but otherwise identical in composition. Furthermore, by combining interfacial DCC with resin-based DCC, an 80% reduction of shrinkage-induced stress is observed in a thiol-ene system "equipped" with both types of DCC mechanisms relative to the composite without DCC in either the resin or at the resin-filler interface. SIGNIFICANCE This behavior highlights the advantages of utilizing the DCC at the resin-filler interface as a stress-relieving mechanism that is compatible with current and future developments in the field of dental restorative materials, nearly independent of the type of resin improvements and types that will be used, as it can dramatically enhance their mechanical performance by reducing both polymerization and mechanically applied stresses throughout the composite lifetime.

中文翻译:

牙科修复材料中的动态共价化学(DCC):在树脂-填充剂界面上实现基于DCC的自适应界面(AI),以提高性能。

目的牙科修复性复合材料已得到广泛研究,目的是改善材料性能。然而,由聚合收缩,热和其他应力以及甲基丙烯酸酯基复合材料的低断裂韧性引起的应力诱发的微裂纹仍然是重大问题。本文中,该研究致力于通过将能够将硫醇-硫酯(TTE)DCC的部分偶联到树脂-填料界面上,将基于动态共价化学(DCC)的自适应界面应用于常规BisGMA / TEGDMA(70:30)牙科树脂。诱导界面应力松弛并促进界面愈合的手段。方法用TTE官能化的硅烷对二氧化硅纳米颗粒(SNP)进行功能化,以使界面与网络共价键合,同时通过DCC促进填料-基质界面的松弛。将官能化的颗粒掺入否则为静态的常规BisGMA / TEGDMA(70:30)牙科树脂中。研究了界面键交换在响应收缩和其他应力,弯曲模量和韧性方面增强牙科复合材料性能的作用。用张力计和FTIR光谱法监测收缩应力。弯曲模量/强度和弯曲韧性通过在通用试验机上的三点弯曲来表征。结果当激活界面TTE键交换时,收缩应力降低了30%,不仅保持而且还增强了复合材料的机械性能。这些改进包括杨氏模量增加了60%,弯曲强度增加了33%,韧性增加了35%,相对于不能进行DCC但在组成上相同的复合材料。此外,通过将界面DCC与基于树脂的DCC结合,相对于树脂或树脂中不含DCC的复合材料,在“配备”两种类型的DCC机理的“硫醇-烯系统”中,可观察到80%的收缩诱导应力降低。树脂-填充物界面。意义这种行为凸显了在树脂-填充剂界面使用DCC作为应力消除机制的优势,该机制与牙科修复材料领域的当前和未来发展兼容,几乎与树脂改良剂的类型和类型无关。可以使用它,因为它可以通过降低复合材料寿命期间的聚合和机械施加的应力来显着提高其机械性能。
更新日期:2019-12-04
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