Institute of Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, Universitaetsstr. 5-7, 45117 Essen, Germany.
Microstructure Physics and Alloy Design, Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Düsseldorf, Germany.
Acta Biomater. 2014 Sep;10(9):3959-68. doi: 10.1016/j.actbio.2014.04.028. Epub 2014 May 4.
The outer part of shark teeth is formed by the hard and mineral-rich enameloid that has excellent mechanical properties, which makes it a very interesting model system for the development of new bio-inspired dental materials. We characterized the microstructure, chemical composition and resulting local mechanical properties of the enameloid from teeth of Isurus oxyrinchus (shortfin mako shark) by performing an in-depth analysis using various high-resolution analytical techniques, including scanning electron microscopy, qualitative energy-dispersive X-ray spectroscopy and nanoindentation. Shark tooth enameloid reveals an intricate hierarchical arrangement of thin (50-80nm) and long (>1μm) crystallites of fluoroapatite with a high degree of structural anisotropy, which leads to exceptional mechanical properties. Both stiffness and hardness are surprisingly homogeneous in the shiny layer as well as in the enameloid: although both tooth phases differ in structure and composition, they show almost no orientation dependence with respect to the loading direction of the enameloid crystallites. The results were used to determine the structural hierarchy of shark teeth, which can be used as a base for establishing design criteria for synthetic bio-inspired and biomimetic dental composites.
鲨鱼牙齿的外部是由坚硬且富含矿物质的釉质形成的，具有出色的机械性能，这使其成为开发新型仿生牙齿材料的非常有趣的模型系统。我们通过使用各种高分辨率分析技术，包括扫描电子显微镜、定性能量色散 X 射线光谱和纳米压痕技术，对短鳍真鲨（Isurus oxyrinchus）牙齿的釉质进行了深入分析，以表征其微观结构、化学成分和局部力学性能。鲨鱼牙齿的釉质显示出薄（50-80nm）而长（>1μm）的氟磷灰石晶体的复杂层次排列，具有高度的结构各向异性，从而产生了出色的机械性能。在闪亮层以及釉质中，弹性模量和硬度都非常均匀：尽管这两个牙齿相在结构和组成上有所不同，但它们在釉质晶体的加载方向上几乎没有取向依赖性。这些结果用于确定鲨鱼牙齿的结构层次，可以作为建立仿生和仿生牙科复合材料设计标准的基础。
