Zaytsev Dmitry, Panfilov Peter
Ural Federal University, Institute of Natural Sciences, Ekaterinburg, Russia.
Ural Federal University, Institute of Natural Sciences, Ekaterinburg, Russia.
Mater Sci Eng C Mater Biol Appl. 2014 Oct;43:607-13. doi: 10.1016/j.msec.2014.07.051. Epub 2014 Aug 4.
Deformation behavior and mechanical properties of samples of human dentin having different geometries were studied under compression in liquid nitrogen. In this case, the plastic response of the collagen fibers in dentin was excluded. The findings were compared with the mechanical properties of dentin at room temperature. Such a comparison allows the plastic contribution of collagen in human dentin to be estimated for samples of different shapes. It was shown that the deformation behavior of human dentin under compression is similar at 77K and 300 K. The dentin samples with low aspect ratio exhibited almost brittle behavior, whereas those with high aspect ratio were prone to considerable deformation. SEM study of the fracture surfaces of samples tested at room and liquid nitrogen temperatures has shown that they are similar. Examination of cracks on the compression surface of samples agrees with this conclusion. However, the mechanical characteristics of dentin depended on the temperature of testing. The compression strength and elastic deformation of dentin at 77K are higher than these parameters at room temperature, while the plasticity of dentin at 77K is lower. The plastic contribution of collagen fibers at room temperature was estimated on the basis of this comparison. The total plasticity of dentin is the sum of the contributions of both collagen and the geometry of the sample. The plasticity of dentin samples having a low aspect ratio is provided by collagen fibers only, while geometric factors are dominant for samples with a high aspect ratio. The contribution of collagen fibers to the plasticity of dentin depends on the geometry of samples with an intermediate aspect ratio.
研究了不同几何形状的人牙本质样本在液氮中压缩时的变形行为和力学性能。在这种情况下，排除了牙本质中胶原纤维的塑性响应。将这些结果与牙本质在室温下的力学性能进行了比较。这样的比较能够估计不同形状样本中胶原在人牙本质中的塑性贡献。结果表明，人牙本质在压缩时77K和300K下的变形行为相似。低长径比的牙本质样本表现出几乎脆性的行为，而高长径比的样本则易于发生显著变形。对在室温和液氮温度下测试的样本断裂表面的扫描电子显微镜研究表明它们相似。对样本压缩表面裂纹的检查与这一结论相符。然而，牙本质的力学特性取决于测试温度。牙本质在77K时的抗压强度和弹性变形高于室温下的这些参数，而77K时牙本质的可塑性较低。基于这种比较估计了室温下胶原纤维的塑性贡献。牙本质的总可塑性是胶原和样本几何形状贡献的总和。低长径比的牙本质样本的可塑性仅由胶原纤维提供，而几何因素对于高长径比的样本占主导地位。胶原纤维对牙本质可塑性的贡献取决于具有中等长径比样本的几何形状。
