制作缺陷致双层瓷修复体崩瓷失效的规律及断裂过程机制的研究

Various lab machining processes will introduce surface and internal fabrication defects into the bilayered ceramic restorations, which have been shown to play a critical role in triggering clinical catastrophic fracture and veneer chipping. Recent studies conducted by the present applicant indicated that not all fabrication defects appear to act as crack origins. Rather the failure of restorations is directly related to the location and size of some key (or fatal) defects as well as the fracture resistance property of the ceramic materials used. This project proposal aims to clarify the characteristic distribution and size of the "fatal" fabrication defects and to identify their origins and the mechanisms of failure originating from these defects. This project study mainly consists of two parts; one part is to construct valid three-dimensional (3D) digital models based on ultrahigh resolution micro-CT and then build up finite element (FE) models of the in-vitro samples and will be used to evaluate the appearance and distribution characteristic of superficial and internal fabrication defects in both lithium disilicate and zirconia based bilayered ceramic restorations; the other part is to perform cross-checking and comparison between the results from the experimental characterization and FE simulation, and quantitatively determine the location, shape and size as well as the root cuase of the "fatal" fabracation defects in bilayered ceramic restorations. In addition, it is proposed to elucidate the essential feature and associated mechanism for the origin of the fabracation defect-caused failure. Up on the completion of the project, it is envisaged that the outcomes of the study would indicate the limitations of current dental ceramic materials and fabrication technique, additionally provide experimental and theoretical background for development of ceramic materials and quality control of ceramic restorations, as well as reduce the clinical failure rate of the all-ceramic restorations.

不同制作工艺会在双层瓷修复体表面及内部引入各种类型的缺陷，其中一些缺陷是导致修复体崩瓷及断裂失效的重要原因。申请人近期研究结果指出并非所有的制作缺陷均可成为裂纹源，修复体的断裂失效与某些关键缺陷的尺寸、部位及材料的抗折性能等有关。本项目拟探索不同制作工艺及材料中关键缺陷（或称为"致命"缺陷）的形貌分布特征及其导致双层瓷修复体失效的作用机制。研究内容包括两部分：一是显微CT扫描后重建与体外实验试件一致的三维数字模型及有限元模型，定量分析二硅酸锂及氧化锆双层瓷修复体表面及内部缺陷的形貌分布特征；二是通过有限元模拟与实验表征结果相互校验，明确双层瓷修复体中"致命"缺陷的成因、部位、形态及尺寸参数，揭示关键缺陷导致双层瓷修复体崩瓷及断裂失效的本质规律与过程机制。研究旨在明确现有材料及修复体制作工艺的不足之处，为牙科全瓷材料工艺的发展及修复体的质量检测提供实验与理论依据，减少临床失效的发生。

不同制作工艺会在双层瓷修复体表面及内部引入各种缺陷，其中一些缺陷是导致修复体崩瓷及断裂失效的重要原因。申请人近期研究结果指出并非所有的制作缺陷均可成为裂纹源，修复体的断裂失效与某些关键缺陷的尺寸、部位及材料的抗折性能等有关。本项目拟探索不同制作工艺及材料中关键缺陷（或称为“致命”缺陷）的形貌分布特征及其导致双层瓷修复体失效的作用机制。研究内容包括两部分：一是显微CT扫描后重建与体外实验试件一致的三维数字模型及有限元模型，定量分析二硅酸锂及氧化锆双层瓷修复体表面及内部制作缺陷的形貌分布特征；二是通过有限元模拟结果与体外实验表征相互校验，明确双层瓷修复体中“致命”缺陷的成因、部位、形态及尺寸参数，揭示关键缺陷导致双层瓷修复体崩瓷及断裂失效的本质规律与过程机制。研究旨在明确现有材料及修复体制作工艺的不足之处，为新型牙科全瓷材料工艺的发展及修复体的质量检测提供实验与理论依据，减少临床失效的发生。