人牙釉质的微压痕断裂行为。
Micro-indentation fracture behavior of human enamel.
机构信息
Department of Information and Electronic Materials Engineering, Paichai University, Daejeon 302735, Republic of Korea.
出版信息
Dent Mater. 2010 Jan;26(1):100-4. doi: 10.1016/j.dental.2009.07.015.
OBJECTIVE
The purpose of this study was to determine the crack resistance behavior (K(R)) of human enamel in relation to its microstructure.
METHODS
Human molar teeth were precision cut, polished and tested using Vickers micro-indentation at different loads ranging from 0.98 to 9.8 N. Five indentation load levels were considered, 20 indentation cracks for each load level were introduced on the surface of the test specimen (10 indentations per tooth) and their variability was evaluated using Weibull statistics and an empirical model. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to analyze the crack morphology and propagation mechanisms involved.
RESULTS
The results showed that enamel exhibited increasing cracking resistance (K(R)) with increasing load. It was found that the crack propagation mainly depended on the location and the microstructure it encountered. SEM showed the formation of crack bridges and crack deflection near the indentation crack tip. The crack mode was of Palmqvist type even at larger loads of 9.8 N. This was mainly attributed to the large process zone created by the interwoven lamellar rod like microstructure exhibited by the enamel surface.
SIGNIFICANCE
This study shows that there are still considerable prospects for improving dental ceramics and for mimicking the enamel structure developed by nature.
目的
本研究旨在确定与微观结构有关的人牙釉质的抗裂性能（K(R)）。
方法
采用维氏微压痕法，对人磨牙进行精密切割、抛光和测试，载荷范围为 0.98 至 9.8 N。考虑了 5 个压痕载荷水平，在试件表面引入了 20 个不同载荷水平的压痕裂纹（每个牙齿 10 个压痕），并使用威布尔统计和经验模型评估其变异性。扫描电子显微镜（SEM）和原子力显微镜（AFM）用于分析涉及的裂纹形态和扩展机制。
结果
结果表明，牙釉质的抗裂性能（K(R)）随载荷的增加而增加。发现裂纹扩展主要取决于裂纹所处的位置和遇到的微观结构。SEM 显示在压痕裂纹尖端附近形成了裂纹桥和裂纹偏斜。即使在 9.8 N 的较大载荷下，裂纹模式仍为 Palmqvist 型。这主要归因于牙釉质表面交错的层状棒状微观结构所产生的大加工区。
意义
本研究表明，在改善牙科陶瓷和模仿自然界开发的牙釉质结构方面仍有很大的前景。
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