Cesar Paulo Francisco, Della Bona Alvaro, Scherrer Susanne S, Tholey Michael, van Noort Richard, Vichi Alessandro, Kelly Robert, Lohbauer Ulrich
Department of Biomaterials and Oral Biology, School of Dentistry, University of São Paulo, São Paulo, Brazil.
Post-Graduate Program in Dentistry, Dental School, University of Passo Fundo, Passo Fundo, Brazil.
Dent Mater. 2017 Jun;33(6):575-584. doi: 10.1016/j.dental.2017.03.006. Epub 2017 Apr 6.
The objective is within the scope of the Academy of Dental Materials Guidance Project, which is to provide dental materials researchers with a critical analysis of fracture toughness (FT) tests such that the assessment of the FT of dental ceramics is conducted in a reliable, repeatable and reproducible way.
Fracture mechanics theory and FT methodologies were critically reviewed to introduce basic fracture principles and determine the main advantages and disadvantages of existing FT methods from the standpoint of the dental researcher.
The recommended methods for FT determination of dental ceramics were the Single Edge "V" Notch Beam (SEVNB), Single Edge Precracked Beam (SEPB), Chevron Notch Beam (CNB), and Surface Crack in Flexure (SCF). SEVNB's main advantage is the ease of producing the notch via a cutting disk, SEPB allows for production of an atomically sharp crack generated by a specific precracking device, CNB is technically difficult, but based on solid fracture mechanics solutions, and SCF involves fracture from a clinically sized precrack. The IF test should be avoided due to heavy criticism that has arisen in the engineering field regarding the empirical nature of the calculations used for FT determination.
Dental researchers interested in FT measurement of dental ceramics should start with a broad review of fracture mechanics theory to understand the underlying principles involved in fast fracture of ceramics. The choice of FT methodology should be based on the pros and cons of each test, as described in this literature review.
本目标属于牙科材料学会指导项目的范畴，即对断裂韧性（FT）测试进行批判性分析，以便以可靠、可重复和可再现的方式对牙科陶瓷的FT进行评估。
对断裂力学理论和FT方法进行了批判性综述，以介绍基本的断裂原理，并从牙科研究人员的角度确定现有FT方法的主要优缺点。
推荐的用于测定牙科陶瓷FT的方法有单边“V”形切口梁（SEVNB）、单边预裂纹梁（SEPB）、人字形切口梁（CNB）和弯曲表面裂纹（SCF）。SEVNB的主要优点是通过切割盘易于制作切口，SEPB允许通过特定的预裂纹装置产生原子级尖锐的裂纹，CNB技术难度大，但基于可靠的断裂力学解决方案，SCF涉及从临床尺寸的预裂纹处断裂。由于工程领域对用于FT测定的计算的经验性质提出了严厉批评，因此应避免使用IF测试。
对牙科陶瓷FT测量感兴趣的牙科研究人员应首先广泛回顾断裂力学理论，以了解陶瓷快速断裂所涉及的基本原理。FT方法的选择应基于本综述中所述的每种测试的优缺点。
