Graded Structures for Damage Resistant All-Ceramic Restorations

描述（由申请人提供）：陶瓷因其美观、惰性和生物相容性而广泛用于牙科和骨科假体。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。我们的初步调查已经建立了失败模式和冠厚度，表面条件，陶瓷的性能，和负载条件之间的关系。这些结果表明，整体玻璃陶瓷冠和氧化铝贴面冠容易发生近接触咬合损伤和粘结内表面径向断裂，而Y-TZP贴面冠由于氧化锆支架的上级强度优越，容易发生贴面断裂。这些结果与临床报告一致。陶瓷修复体的断裂问题促使我们利用功能梯度材料开发新一代抗损伤陶瓷修复体。最新的理论和实验进展表明，在功能梯度材料中，接触损伤的阻力是前所未有的，否则无法在传统的均匀材料中实现。我们的长期目标是开发一种美观、坚固、薄的氧化锆基功能梯度材料，用于微创全瓷后冠和桥，为骨科和其他工程应用奠定基础。本提案的目的是制造和验证从顶部和底部表面连续渐变的陶瓷层结构的接触和弯曲损伤抗性。我们建议通过两个具体目标来实现这一目标：1.开发和表征一种新的玻璃/氧化锆/玻璃复合材料，其具有从外表面（低模量玻璃-陶瓷）到内部（坚固、致密、细粒氧化锆）的连续弹性模量梯度;以及2.优化玻璃/氧化锆/玻璃在水中循环载荷下的功能-性能（美观性、抗损伤性-微观结构）关系。我们的初步研究表明，功能梯度玻璃/氧化锆/玻璃夹层结构，具有改善的抗损伤性和美学相比，他们的散装氧化锆对应物，可以通过渗透到预烧结氧化锆的表面低弹性模量的玻璃陶瓷。与公共卫生的相关性：从这项调查中产生的知识将指导新一代功能梯度陶瓷牙科和骨科假体的设计，通过抵抗接触损伤和弯曲疲劳，降低发病率和公众更换成本，提高寿命。

DESCRIPTION (provided by applicant): Ceramics are widely used in dental and orthopedic prostheses because of their aesthetics, inertness, and biocompatibility. 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. Our preliminary investigations have established relations between failure modes and crown thickness, surface conditions, properties of the ceramic, and loading conditions. These findings indicate that monolithic glass- ceramic crowns and veneered alumina crowns are vulnerable to both near-contact occlusal damages and cementation internal surfaces radial fractures, while the veneered Y-TZP crowns are prone to veneer fracture owing to the superior strength of zirconia frameworks. These findings are consistent with clinical reports. It is the fracture problem of ceramic prostheses that motivated us to develop a new generation of damage resistant ceramic prostheses utilizing functionally graded materials. Recent theoretical and experimental advances demonstrate unprecedented resistance to contact damage in functionally graded materials that otherwise cannot be realized in conventional homogeneous materials. Our long-term goal is to develop an aesthetic, strong, thin zirconia based functionally graded material for less invasive all-ceramic posterior crowns and bridges, foreshadowing possibilities for orthopedic and other engineering applications. The objective of this proposal is to fabricate and validate the contact and flexural damage resistances of ceramic layer structures with continuous gradation from both top and bottom surfaces. We propose to achieve this objective through two specific aims: 1. Develop and characterize a new glass/zirconia/glass composite with continuous elastic modulus gradation from outer surfaces (low modulus glass-ceramic) to interior (strong, dense, fine-grain zirconia); and 2. Optimize the function-property (aesthetics, damage resistance-microstructure) relation of glass/zirconia/glass subjected to cyclic loading in water. Our preliminary studies have demonstrated that a functionally graded glass/zirconia/glass sandwich structure with improved damage resistance and aesthetics compared to their bulk zirconia counterparts can be produced by infiltrating a low elastic modulus glass-ceramic into the surfaces of a presintered zirconia. Relevance to public health: Knowledge generated from this investigation will guide design of a new generation of functionally graded ceramic dental and orthopedic prostheses with improved lifetime by resistance to contact damage and flexural fatigue, reducing morbidity and costs of replacement to the public.