Spatial distribution of the human enamel fracture toughness with aging.
Spatial distribution of the human enamel fracture toughness with aging.
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DOI：
10.1016/j.jmbbm.2013.04.025
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发表时间：
2013-10
影响因子：
3.9
通讯作者：
Q. Zheng;Haiping Xu;F. Song;Lan Zhang;Xuedong Zhou;Y. Shao;Dingming Huang
中科院分区：
文献类型：
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作者：
Q. Zheng;Haiping Xu;F. Song;Lan Zhang;Xuedong Zhou;Y. Shao;Dingming Huang
深入了解人牙釉质的断裂韧性(KIC)及其随年龄的变化，对临床治疗牙体裂纹和骨折具有重要意义。我们对年轻患者(18≤Agee≤25)和老年患者(55≤Agee)的磨牙进行了微压痕测试和化学含量测量。通过维氏韧性测试和能谱分析，分别测定了牙冠尖区和牙尖间区外、中、内釉质层的KIC和矿物质(钙、磷)含量。通过基于原子力显微镜(AFM)的纳米压痕测试测量了用于KIC计算的弹性模数。在外釉质层，分别计算两个方向的KIC值(方向I，平行于咬合面的裂缝；方向II，垂直于方向I)。外层釉质的KIC平均值低于内层(p<；0.05)。两组在力学性能方面没有发现其他与区域相关的差异。在外层釉质中，老年牙釉质的KIC、II低于年轻牙釉质，矿物质含量高于年轻牙釉质(p<；0.05)。随着年龄的增长，釉质表面更容易出现裂纹，部分原因是随着釉质的成熟，釉质表面的棱柱间有机基质减少。
A better understanding of the fracture toughness (KIC) of human enamel and the changes induced by aging is important for the clinical treatment of teeth cracks and fractures. We conducted microindentation tests and chemical content measurements on molar teeth from “young” (18≤age≤25) and “old” (55≤age) patients. The KIC and the mineral contents (calcium and phosphorus) in the outer, the middle, and the inner enamel layers within the cuspal and the intercuspal regions of the crown were measured through the Vickers toughness test and Energy Dispersive X-Ray Spectroscopy (EDS), respectively. The elastic modulus used for the KIC calculation was measured through atomic force microscope (AFM)-based nanoindentation tests. In the outer enamel layer, two direction-specific values of the KIC were calculated separately (direction I, crack running parallel to the occlusal surface; direction II, perpendicular to direction I). The mean KIC of the outer enamel layer was lower than that of the internal layers (p<0.05). No other region-related differences in the mechanical properties were found in both groups. In the outer enamel layer, old enamel has a lower KIC, II and higher mineral contents than young enamel (p<0.05). The enamel surface becomes more prone to cracks with aging partly due to the reduction in the interprismatic organic matrix observed with the maturation of enamel.