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

描述（由申请人提供）：陶瓷因其美学价值和化学惰性而广泛用于牙科和骨科应用。然而，陶瓷容易断裂，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和生产生活方式的丧失。尽管在材料性能方面有所改进，但全陶瓷涂层的性能仍然无法与金属-陶瓷涂层的“黄金标准”相匹配。我们以前的研究已经建立了失效模式和修复厚度，表面条件，陶瓷性能和加载条件之间的关系。这些结果表明，整体式玻璃陶瓷和饰面氧化铝瓷容易受到咬合滑动接触损伤和粘结体断裂，而饰面氧化锆瓷更容易发生饰面剥落和分层。这些结果与临床报告一致。 从我们目前的NIDCR支持的项目的理论和实验工作的最新进展表明，单板故障和散装断裂可以大大减轻恢复层内的控制成分梯度。这种梯度结构相对于它们的均质对应物表现出显著更高的抗滑动接触损伤和抗弯曲整体断裂性。在这种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学上正确的几何形状中，具有和不具有薄饰面（0.3 mm）的分级玻璃氧化锆材料的增强的抗碎裂、饰面/芯层分层和口部运动疲劳性。这将使我们更接近于解决临床问题-陶瓷涂层的碎裂、分层和断裂。此外，我们建议建立一个简单但功能强大的边缘压痕技术来评估梯度层压板的韧性性能，一个问题领域，超出了目前的断裂测试协议的范围。我们建议通过三个具体目标来实现这些目标：1.量化增加电阻梯度氧化锆结构的边缘缺口使用一种新的边缘压痕技术; 2。使用新的裂纹扩展技术和传统的剪切粘结试验阐明梯度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学正确的玻璃/氧化锆/玻璃分级结构相对于商业贴面和整体氧化锆系统的抗疲劳损伤性。从这项调查中产生的知识将促进智能玻璃氧化锆梯度结构的发展，下一代牙科和骨科假体具有改善的损伤容限，美学和粘结性能。这些改进将导致减少假牙的发病率和公众更换假牙的费用。

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.