Fractal Analysis of Ceramic FPDs

描述(申请人提供)：陶瓷假体的断裂面可以用分形几何来表征，以提供关于材料特性和故障时存在的条件的丰富信息。这一潜在的有用的方法也没有被广泛使用，因为目前的分形分析方法是劳动密集型的、技术敏感的，并且有统计上的偏见。我们团队开发了一种新的失效分析方法。它是一种自动化的、无偏的方法，可以快速而精确地测量断口表面的分维增量(D*)。拟议的项目旨在验证该工具作为一种使能技术，从而能够(1)确定多层结构中的失效原因和(2)确定材料的断裂韧性，这两项都有助于改进材料加工。此外，以前的工作使我们假设，可以通过分析破损假体的任何片段的D*来确定(1)和(2)--即使在故障起因已经丢失或损坏的情况下。此外，当关键缺陷在 在断裂面上，我们应该能够估计失效时的应力，这将有助于诊断半功能和/或是否存在非典型残余应力。我们将通过将我们在两种基准材料(石英玻璃和NIST标准化的Si3N4)上的结果与文献中相同材料的值进行比较，来测试这项技术的准确性。我们将通过验证我们的能力来测试这项技术的实用性，以检测三种商业牙科陶瓷中哪一种是双层试件(瓷质玻璃陶瓷贴面、瓷质氧化锆贴面和微晶玻璃贴面氧化锆)的失败来源。拟议项目有三个总体目标：(1)验证我们的创新技术，用于具有已知破坏应力水平的标准几何形状的单层和双层弯曲梁试件。(2)验证我们的创新技术在全瓷固定局部义齿(全冠和三单元FPD)上的应用。(3)确定偏离临床情况的测试条件的影响(单调载荷与循环载荷、潮湿环境与干燥环境)。由此产生的信息将对口腔修复领域产生巨大的潜在影响，也可能适用于矫形外科以及汽车、航空航天和半导体行业中使用的陶瓷部件。

DESCRIPTION (provided by applicant): The fracture surfaces of ceramic prostheses can be characterized using fractal geometry to provide a wealth of information about the material properties and the conditions that were present at the time of failure. This potentially useful too is not widely employed because the current methods of fractal analysis are labor intensive, technique sensitive, and statistically biased. Our team has developed a new failure analysis method. It is an automated, unbiased method of rapidly and precisely measuring the fractal dimensional increment (D*) of fracture surfaces. The proposed project aims to validate this tool as an enabling technology to allow (1) determination of the failure origin in multilayered structures and (2) determination of material fracture toughness, both of which are useful in improving material processing. Furthermore, prior work leads us to hypothesize that both (1) and (2) can be determined from analyzing the D* of any fragment of a broken prosthesis - even when the failure origin has been lost or damaged. In addition, when the critical flaw is visible on the fracture surface, we should be able to estimate the stress at failure, which will be useful in diagnosing parafunction and/or the presence of an atypical residual stress. We will test the accuracy of this technique by comparing our results on two benchmark materials (silica glass and NIST standardized Si3N4) to the values in the literature for the same materials. We will test the utility of this technique by verifying our ability to detect which of three commercially availale dental ceramics is the failure origin in bilayered specimens (glass-ceramic veneered with porcelain, zirconia veneered with porcelain, and zirconia veneered with glass-ceramic). There are three overall goals of the proposed project: (1) Validate our innovative technique for use on monolithic and bilayered flexure beam specimens having a standard geometry with known failure stress levels. (2) Validate our innovative technique for use on all-ceramic fixed partial dentures (both crowns and three-unit FPDs). (3) Determine the effects of test conditions that deviate from the clinical case (monotonic vs. cyclic loading and wet vs. dry environment). The resulting information will have a high potential impact on the field of prosthodontics and may also be applicable to ceramic components used in orthopedic surgery and the automotive, aerospace, and semiconductor industries.