中文摘要：

目的通过有限元数值计算的方法研究年龄变化对牙本质断裂力学行为的影响。方法根据典型的紧凑拉伸试件形式建立有限元模型,采用内聚力模型分别模拟裂纹在年轻和老龄牙本质中稳态扩展的过程,并进行比较。结果老龄牙本质的扩展断裂韧度和断裂韧度趋于恒定时的值分别为0.51、1.19 MPa.m1/2,显著小于年轻牙本质的相应值（7.48、1.71 MPa.m1/2）;然而,这两者之间的初始断裂韧度相差比较微小,年轻和老龄牙本质的初始断裂韧度分别为0.51和0.38 MPa.m1/2。结论随着年龄的增长,牙本质抵抗裂纹扩展的能力发生了明显的减弱。基于内聚力模型的数值方法能够很好地预测牙本质等力学性能与年龄相关的生物硬组织材料的裂纹扩展行为。

英文摘要：

Objective To investigate effects of aging on the fracture mechanical behavior of human dentin with fi- nite element numerical method. Methods The finite element model was established according to the typical compact tension specimen in the experiment. The stable crack growth in human dentin was simulated with the co- hesive zone model to compare the crack extensions of the young and aged dentin. Results The growth tough- ness and plateau toughness of the aged dentin were 0.51 and ]. 19 MPa · m1/2, respectively, which were signifi- cantly lower than those of the young dentin （？. 48, 1. 71 MPa · m1/2）. However, the initiation toughness of the young and aged dentin showed no significant difference with 0.51 and 0.38 MPa · m1/2, respectively. Conclusions The crack growth resistance of human dentin is decreased significantly with aging. Based on the cohesive zone model, the crack growth behavior of biological hard tissue, whose mechanical properties are related with age （such as the human dentin）, can be well predicted by using numerical methods.