Understanding the microstructural bonding mechanisms between Y-TZP and veneering ceramic

迄今为止，牙科贴面氧化锆基核修复体已得到广泛应用。氧化锆芯采用瓷贴面材料分层，达到了合适的美学效果。然而，氧化锆基修复体可能会造成临床问题，如瓷贴面层碎裂或断裂。以前的研究已经报道了贴面失效的显著发生率，如分层、碎裂和开裂。这种断裂行为可归因于单板/芯材界面结合强度差、芯材与单板之间的弹性模数不匹配、芯材与单板之间的热膨胀系数不匹配、陶瓷强度较低以及因冷却速度和/或高温烧结而产生残余应力的热加工过程。为提高烤瓷与烤瓷之间的界面相容性，避免早期破坏，应对氧化锆/瓷界面有更深入的了解。*拟议的研究将探索氧化锆/陶瓷界面粘结的详细机理，以开发一种可行的解决方案，使用两种成型技术(分层技术和压制技术)来改善这两种材料之间的粘结。还将对热应力进行评估。这项研究的主要目的是表征陶瓷和氧化锆之间的相互作用，然后根据结果开发材料或新的设计。因此，全瓷修复体的瓷贴面与氧化锆核之间可以获得更好的粘结稳定性。瓷贴面与氧化锆的粘结是氧化锆基修复体成功的基础。在确定了制作氧化锆基修复体的新方案和/或设计后，将进行力学测试。*将仔细进行不同的测试，以描述氧化锆瓷粘结的微观结构机理。用扫描电子显微镜、能谱仪、电子背散射衍射仪(EBSD)进行了测试。此外，还将利用EBSD对显微组织、织构、缺陷、晶粒形态和变形进行评估。此外，聚焦离子束显微镜(FIB)将用于制备用于透射电子显微镜和飞行时间二次离子质谱仪(TOF-SIMS)的薄样品。俄歇微探针将有助于以高空间分辨率确定表面的二维和三维元素分布。本研究的成果是为牙科实验室提供一种新的制作牙科贴面氧化锆核修复体的方法，以提高这类牙体修复体的成功率。新的协议将基于从本研究结果获得的氧化锆/陶瓷界面的详细结合机制。在5年的时间里，我将培养3名研究生。

Dental veneered zirconia-based core restorations have been used widely to date. The zirconia core is layered with a porcelain veneer material to achieve suitable esthetics. However, zirconia-based restorations can create clinical issues such as chipping or fracture of the porcelain veneered layer. Previous studies have reported a significant incidence of veneer failures such as delaminations, chipping and cracking. This fracture behavior could be attributed to the poor veneer/core interface bond strength, elastic modulus mismatch between the core material and the veneer, coefficient of thermal expansion mismatch between the core and the veneer, weak porcelain strength and thermal procedure which could introduce residual stress induced by cooling rate and/or sintering at high temperatures. To improve the compatibility at the interface between veneer and core, and to avoid premature failure, the interface zirconia/porcelain should be better understood. ***The proposed research will investigate the detailed mechanism for the adhesion at the interface zirconia/porcelain to develop a feasible solution to improve the bonding between these two materials, using both molding techniques (the layering technique and the press technique). The thermal stresses will be also evaluated. The main objectives of this study are to characterize the interaction between porcelain and zirconia then, materials or new designs will be developed based on the results. Therefore, better bonding stability between porcelain veneer and zirconia core of an all-ceramic restoration can be achieved. The adhesion of porcelain veneer to zirconia is fundamental for the success of the zirconia-based restorations. After determining the new protocol and/or design to fabricate zirconia-based restorations, mechanical tests will be performed.***Different tests will be carefully conducted to describe the microstructural mechanisms of zirconia/porcelain bond. The tests are SEM, EDS, Electron Backscatter Diffraction (EBSD). Furthermore, microstructures, texture, defects, grain morphology and deformation will also be evaluated by EBSD. In addition, the Focused Ion Beam microscopy (FIB) will be used to prepare thin specimens for the TEM and for Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS). Auger Microprobe will contribute to the determination of 2D and 3D elemental distributions on surfaces with high spatial resolution. The bond formation of the zirconia to porcelain will also be examined by XPS.***The outcome of the research is to provide the dental laboratories with a new protocol to fabricate dental veneered zirconia-based core restorations in order to improve the success rate of this type of dental restoration. The new protocol will be based on the detailed bond mechanisms at the zirconia/porcelain interface obtained from the results of this study. Over 5 years, I will train 3 graduate students.