Graded Structures for Damage Resistant All-Ceramic Restorations

说明(申请人提供)：陶瓷因其美观、惰性和生物相容性而被广泛应用于牙科和矫形修复体。然而，陶瓷很容易破裂，每年的更换成本高达数百万美元，可能会导致患者严重不适，失去有效的生活方式。我们的初步研究已经建立了失效模式与牙冠厚度、表面条件、陶瓷性能和加载条件之间的关系。这些结果表明，整体微晶玻璃冠和贴面氧化铝冠容易受到近接触性咬合损伤和粘结内表面的径向断裂的影响，而贴面Y-TZP冠由于氧化锆支架的优异强度而容易发生贴面断裂。这些发现与临床报告一致。正是陶瓷假体的断裂问题促使我们开发了利用功能梯度材料的新一代抗损伤陶瓷假体。最近的理论和实验进展表明，在传统的均匀材料中，功能梯度材料的接触损伤是无法实现的，这是前所未有的。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，用于侵入性较小的全陶瓷后牙冠和桥，为矫形外科和其他工程应用奠定基础。该方案的目的是制造和验证顶部和底部连续渐变的陶瓷层结构的接触和弯曲损伤抗力。我们建议通过两个具体的目标来实现这一目标：1.开发和表征一种从外表面(低模数微晶玻璃)到内表面(强、致密、细晶的氧化锆石)具有连续弹性模数级配的新型玻璃/氧化锆/玻璃复合材料；2.优化水中循环载荷下玻璃/氧化锆/玻璃的功能-性能(美学、抗损伤-微结构)关系。我们的初步研究表明，通过将低弹性模数的微晶玻璃渗透到预烧的氧化锆表面，可以制备出比块状氧化锆抗损伤能力和美观程度更高的功能梯度玻璃/氧化锆/玻璃夹层结构。与公众健康相关：这项研究产生的知识将指导新一代功能梯度陶瓷牙科和矫形修复体的设计，通过抵抗接触损伤和弯曲疲劳来延长寿命，降低公众的发病率和更换成本。

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.