Graded Zirconia Structures for Resistance to Chipping, Delamination, and Fatigue

描述（申请人提供）：陶瓷因其美学价值和化学惰性而广泛应用于牙科和骨科。然而，陶瓷易骨折，每年的更换成本高达数百万美元，并可能导致患者严重不适，失去富有成效的生活方式。尽管材料性能有所改善，但全陶瓷修复体的性能仍然无法达到金属陶瓷修复体的“黄金标准”。我们之前的研究已经建立了破坏模式与修复厚度、表面条件、陶瓷性能和加载条件之间的关系。综上所述，整体玻璃陶瓷修复体和贴面氧化铝修复体易发生咬合滑动接触损伤和胶结体断裂，而贴面氧化锆修复体易发生贴面碎裂和脱层。这些发现与临床报告一致。目前nidcr支持的项目的理论和实验工作的最新进展表明，通过控制恢复层内的成分梯度，可以大大减轻单板破坏和整体断裂。这种梯度结构相对于均匀结构具有更高的抗滑动接触损伤和弯曲体断裂的能力。在这个竞争性的更新应用中，我们建议阐明在平面模型结构和解剖正确的几何形状中，有或没有薄贴面（0.3 mm）的分级氧化玻璃材料增强的抗切屑、贴面/芯层剥离和口部运动疲劳。这将使我们更接近解决陶瓷修复体的碎裂、脱层和断裂等临床问题。此外，我们建议建立一种简单但功能强大的边缘压痕技术来评估渐变层压板的韧性特性，这是目前断裂测试协议范围之外的一个问题领域。我们建议通过三个具体目标来实现这些目标：利用一种新的边缘压痕技术，量化分级氧化锆结构边缘切屑的阻力增加；2. 利用一种新的裂纹扩展技术和传统的剪切粘结试验来阐明分级氧化锆结构的裂纹-界面相互作用；和3。在潮湿环境中，使用口腔运动模拟器确定具有或不具有薄瓷贴面的解剖正确的玻璃/氧化锆/玻璃分级结构相对于商业贴面和单片氧化锆系统的疲劳损伤抵抗力。从这项研究中获得的知识将促进下一代牙科和骨科假体的智能玻璃-氧化锆分级结构的发展，这些结构具有更好的损伤耐受性、美观性和粘合性。这些改进将会降低义齿的发病率和公众的替代费用。

DESCRIPTION (provided by applicant): Ceramics are widely used in dental and orthopedic applications because of their esthetic value and chemical inertness. However, ceramics are vulnerable to fracture which accounts for millions of dollars annually in replacement costs and can cause significant patient discomfort and loss of productive lifestyle. Despite improvements in material properties, the performance of all-ceramic restorations still fails to match the 'gold standard' of metal-ceramic restorations. Our previous investigations have established relations between failure modes and restoration thickness, surface conditions, ceramic properties, and loading conditions. These findings indicate that monolithic glass-ceramic and veneered-alumina restorations are vulnerable to both occlusal sliding-contact damage and cementation bulk fracture, while the veneered zirconia restorations are prone to veneer chipping and delamination. These findings are consistent with clinical reports. Recent advances in theoretical and experimental work from our current NIDCR-supported project have demonstrated that veneer failure and bulk fracture may be substantially mitigated by controlled compositional gradients within the restoration layer. Such graded structures exhibit significantly higher resistance to sliding- contact damage and flexural bulk fracture relative to their homogeneous counterparts. In this competing renewal application we propose to elucidate enhanced resistance to chipping, veneer/core delamination, and mouth-motion fatigue of graded glass-zirconia materials with and without a thin veneer (0.3 mm) in both flat model structures and anatomically-correct geometries. This will bring us closer to a solution of a clinical problem-chipping, delamination, and fracture of ceramic restorations. Additionally, we propose to establish a simple but powerful edge-indentation technique to assess the toughness properties of graded laminates, a problem area that lies beyond the scope of current fracture testing protocols. We propose to achieve these objectives through three specific aims: 1. Quantify increased resistance to edge-chipping of graded zirconia structures using a novel edge-indentation technique; 2. Elucidate crack-interface interaction of graded zirconia structures using a novel crack growth technique and a conventional shear bond test; and 3. Determine resistance to fatigue damage of anatomically-correct glass/zirconia/glass graded structures with or without a thin porcelain veneer relative to commercial veneered and monolithic zirconia systems using a mouth-motion simulator in wet environments. Knowledge generated from this investigation will facilitate the development of smart glass-zirconia graded structures for next-generation dental and orthopedic prostheses with improved damage-tolerance, esthetics, and cementation properties. These improvements will lead to reduced morbidity of dental prostheses and cost of replacement to the public.