Structure, composition, and mechanical properties of shark teeth
Structure, composition, and mechanical properties of shark teeth
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DOI：
10.1016/j.jsb.2012.03.012
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发表时间：
2012-06-01
影响因子：
3
通讯作者：
Epple, Matthias
中科院分区：
文献类型：
--
作者：
Enax, Joachim;Prymak, Oleg;Epple, Matthias
对两种不同鲨鱼物种（Isurus oxyrinchus 和 Galeocerdo cuvier）的牙齿和地质氟磷灰石单晶进行了结构和化学表征。与牙本质相反，釉质显示出尖锐的衍射峰，表明釉质具有高结晶度。釉质的晶格参数与地质氟磷灰石单晶的晶格参数接近。鲨鱼牙齿的无机部分由氟磷灰石组成，釉质中氟化物含量为3.1 wt.%，即接近地质氟磷灰石单晶的氟化物含量（3.64 wt.%）。扫描电子显微照片显示，釉质中的晶体高度有序，具有特殊的拓扑取向（垂直于外表面，平行于中心）。通过热重分析，测定了两种鲨鱼的牙本质和牙釉质中的水、有机基质和生物矿物质。牙本质比釉质具有更高的水、有机基质和碳酸盐含量，但氟化物含量较少。纳米压痕和维氏显微硬度测试表明，鲨鱼牙齿的釉质大约是牙本质的六倍硬。鲨鱼牙齿和人类牙齿的牙本质和牙釉质/釉质硬度相当。相比之下，由于不存在有机基质，地质氟磷灰石单晶比这两种牙齿都硬得多。总之，鲨鱼牙齿的不同生物学功能（伊苏鲁的“撕裂”和伽莱奥塞多的“切割”）是由不同的几何形状控制的，而不是由化学或晶体成分控制的。 (c) 2012 Elsevier Inc. 保留所有权利。
The teeth of two different shark species (Isurus oxyrinchus and Galeocerdo cuvier) and a geological fluoroapatite single crystal were structurally and chemically characterized. In contrast to dentin, enameloid showed sharp diffraction peaks which indicated a high crystallinity of the enameloid. The lattice parameters of enameloid were close to those of the geological fluoroapatite single crystal. The inorganic part of shark teeth consisted of fluoroapatite with a fluoride content in the enameloid of 3.1 wt.%, i.e., close to the fluoride content of the geological fluoroapatite single crystal (3.64 wt.%). Scanning electron micrographs showed that the crystals in enameloid were highly ordered with a special topological orientation (perpendicular towards the outside surface and parallel towards the center). By thermogravimetry, water, organic matrix, and biomineral in dentin and enameloid of both shark species were determined. Dentin had a higher content of water, organic matrix, and carbonate than enameloid but contained less fluoride. Nanoindentation and Vicker's microhardness tests showed that the enameloid of the shark teeth was approximately six times harder than the dentin. The hardness of shark teeth and human teeth was comparable, both for dentin and enamel/enameloid. In contrast, the geological fluoroapatite single crystal was much harder than both kinds of teeth due to the absence of an organic matrix. In summary, the different biological functions of the shark teeth ("tearing" for Isurus and "cutting" for Galeocerdo) are controlled by the different geometry and not by the chemical or crystallographic composition. (c) 2012 Elsevier Inc. All rights reserved.