Ural Federal University, Ekaterinburg, Russia.
Ural State Medical University, Ekaterinburg, Russia.
Mater Sci Eng C Mater Biol Appl. 2014 Aug 1;41:83-90. doi: 10.1016/j.msec.2014.04.046. Epub 2014 Apr 26.
The cause of difference in deformation behavior of human dentin under compression and bending is discussed. Mechanical properties of dentin under these deformation schemes are compared. Microstructural study of fracture surfaces of samples and cracks in dentin is carried out, too. Dentin behaves like a brittle solid under bending, whereas it exhibits various types of response from brittle to highly deformable under compression that depended on the geometry of sample (d/h ratio of a cubic sample). It is shown that the quantity of cracks on the compressed sample increases when its elasticity and plasticity grow up, whereas under bending the failure of sample occurs due to the advancement of dominant crack. Deformation and crack growth are the channels for the accommodation of applied stress in dentin. Crack growth is the leading one when the level of tensile stress in sample is dominant, whereas deformation becomes the leading channel when compression stress is dominant. However, in both cases contribution of the concurrent channel cannot be ignored. This feature is caused by the ductile fracture mode of dentin on the mesoscopic level.
讨论了导致人牙本质在压缩和弯曲下变形行为差异的原因。比较了牙本质在这些变形方案下的力学性能。还对样品断裂面和牙本质内裂纹的微观结构进行了研究。牙本质在弯曲下表现为脆性固体，而在压缩下则表现出各种从脆性到高可变形的响应，这取决于样品的几何形状（立方样品的 d/h 比）。结果表明，随着压缩样品弹性和塑性的增加，其上的裂纹数量增加，而在弯曲下，由于主导裂纹的扩展，样品发生失效。变形和裂纹扩展是牙本质中适应外加应力的通道。当样品中的拉伸应力占主导地位时，裂纹扩展是主要的，而当压缩应力占主导地位时，变形成为主要的通道。然而，在这两种情况下，都不能忽略并发通道的贡献。这一特征是由牙本质在介观水平上的韧性断裂模式引起的。
