Dentin is a biocomposite possessing complex hierarchical structure, which endows this hard tissue with excellent damage tolerance. In this study, crack growth in dentin at the microstructural scale is investigated and the synergistic effects of plastic deformation of intertubular dentin (ITD), elasticity and fracture properties of peritubular dentin (PTD), and fracture properties of PTD/ITD interface on the fracture of dentin are explored. A micromechanical model is developed, which captures the experimentally observed fracture process of dentin, i.e. occurrence of microcracking of PTD ahead of the main crack. It is found through numerical simulations that high relative stiffness and low cohesive strength of PTD increase the propensity of microcracking of PTD, whereas reduce the plastic dissipation and toughness of the microstructure of dentin. The microcracking of PTD can be also promoted by low toughness of PTD. The large friction angle and weak strain hardening of ITD could promote the microcracking of PTD, and simultaneously enhance the toughness of the microstructure of dentin. In addition, it is identified that the cohesive strength of the PTD/ITD interface plays a crucial role in dominating fracture mechanisms; low cohesive strength leads to fracture of interface and suppresses microcracking of PTD, which provides an explanation for the crack deflection along interface observed in experiments. Nevertheless, the toughness of interface has a negligible influence on the fracture of dentin.

牙本质是具有复杂层次结构的生物复合材料，赋予这种硬组织优异的损伤耐受性。在这项研究中，研究了牙本质在微观结构上的裂纹扩展，并研究了管间牙本质（ITD）的塑性变形，管周牙本质（PTD）的弹性和断裂特性以及PTD / ITD界面的断裂特性对骨折的协同作用。探索牙本质。建立了一个微力学模型，该模型捕获了实验观察到的牙本质的断裂过程，即在主裂纹之前发生了PTD的微裂纹。通过数值模拟发现，PTD的高相对刚度和低内聚强度增加了PTD的微裂纹倾向，而降低了牙本质的塑性消散和韧性。PTD的低韧性也可以促进PTD的微裂纹。ITD的大摩擦角和较弱的应变硬化可以促进PTD的微裂纹，同时增强牙本质组织的韧性。此外，可以确定的是，PTD / ITD界面的内聚强度在控制断裂机理中起着至关重要的作用。低内聚强度会导致界面断裂并抑制PTD的微裂纹，这为实验中观察到的沿界面的挠曲变形提供了解释。然而，界面的韧性对牙本质的断裂影响可忽略不计。同时增强牙本质微观结构的韧性。此外，可以确定的是，PTD / ITD界面的内聚强度在控制断裂机理中起着至关重要的作用。低的内聚强度会导致界面断裂并抑制PTD的微裂纹，这为实验中观察到的沿界面的挠曲变形提供了解释。然而，界面的韧性对牙本质的断裂影响可忽略不计。同时增强牙本质微观结构的韧性。此外，可以确定的是，PTD / ITD界面的内聚强度在控制断裂机理中起着至关重要的作用。低内聚强度会导致界面断裂并抑制PTD的微裂纹，这为实验中观察到的沿界面的挠曲变形提供了解释。然而，界面的韧性对牙本质的断裂影响可忽略不计。