Mechanistic aspects of in vitro fatigue-crack growth in dentin
Mechanistic aspects of in vitro fatigue-crack growth in dentin
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DOI：
10.1016/j.biomaterials.2004.04.051
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发表时间：
2005-04-01
期刊：
影响因子：
14
通讯作者：
Ritchie, RO
中科院分区：
文献类型：
--
作者：
Kruzic, JJ;Nalla, RK;Ritchie, RO
虽然疲劳裂纹的扩展已被认为是牙本质中的一个具有临床意义的问题，但很少有基于断裂力学的研究对该问题进行了研究。在本研究中，在大象牙本质上进行了一系列循环频率（1-50 Hz）的体外循环疲劳实验，以便从理解牙本质疲劳机制的角度量化疲劳裂纹扩展行为。具体而言，裂纹扩展率沿着平行于牙本质小管的方向获得的结果被发现是很好地描述的应力强度范围，AK，使用一个简单的巴黎幂律方法，指数范围从12到32。此外，观察到的频率依赖性的裂纹增长率，与较高的增长率与较低的频率。通过使用涉及交替循环和静态加载的裂纹扩展实验，从机械上确定这种疲劳裂纹扩展是“真正的”循环疲劳机制的结果，而不仅仅是一系列静态断裂事件。此外，基于所观察到的频率依赖性的疲劳裂纹生长在牙本质和随时间变化的裂纹钝化的观察，提出了一个循环疲劳机制，包括裂纹尖端钝化和再锐化。这些结果被认为是重要的，为更好地了解疲劳相关的失败，在牙齿。(C)2004爱思唯尔有限公司保留所有权利。
Although the propagation of fatigue cracks has been recognized as a problem of clinical significance in dentin, there have been few fracture mechanics-based studies that have investigated this issue. In the present study, in vitro cyclic fatigue experiments were conducted over a range of cyclic frequencies (1-50 Hz) on elephant dentin in order to quantify fatigue-crack growth behavior from the perspective of understanding the mechanism of fatigue in dentin. Specifically, results obtained for crack extension rates along a direction parallel to the dentinal tubules were found to be well described by the stress-intensity range, AK, using a simple Paris power-law approach with exponents ranging from 12 to 32. Furthermore, a frequency dependence was observed for the crack-growth rates, with higher growth rates associated with lower frequencies. By using crack-growth experiments involving alternate cyclic and static loading, such fatigue-crack propagation was mechanistically determined to be the result of a "true" cyclic fatigue mechanism, and not simply a succession of static fracture events. Furthermore, based on the observed frequency dependence of fatigue-crack growth in dentin and observations of time-dependent crack blunting, a cyclic fatigue mechanism involving crack-tip blunting and re-sharpening is proposed. These results are deemed to be of importance for an improved understanding of fatigue-related failures in teeth. (C) 2004 Elsevier Ltd. All rights reserved.