目的：通过有限元方法计算裂纹扩展过程中裂纹尖端应力强度因子的变化和裂纹扩展的路径。方法用ANSYS软件建立釉牙本质界结构的有限元模型，在模型的单边缘设置长度为0.1mm的初始裂纹，该数值试样的底端固定，顶端受有б=1MPa的均匀拉伸载荷，加载频率为5Hz。利用ANSYS软件计算裂纹在扩展过程中裂纹尖端的应力强度因子和裂纹在扩展过程中的偏斜角度。结果裂纹到达釉牙本质界时应力强度因子会突然降低并且在釉牙本质界内随裂纹的延伸而降低。裂纹在釉质和牙本质内的偏斜角度小于15°，当裂纹扩展到釉牙本质界时会出现大的偏斜角度，裂纹尖端出现应力降低的现象。结论由于裂纹尖端应力强度因子在釉牙本质界处的降低以及裂纹偏斜，釉牙本质界可能具有阻断裂纹扩展的作用。%Objective This study aims to identify the crack tip stress intensity factor of the propagation process, crack propagation path, and the changes in the shape of the crack tip by the finite element method. Methods The finite element model of dentino-enamel junction was established with ANSYS software, and the length of the initial crack in the single edge was set to 0.1 mm. The lower end of the sample was fixed. The tensile load of 1 MPa with frequency of 5 Hz was applied to the upper end. The stress intensity factor, deflection angle, and changes in the shape of the crack tip in the crack propagation were calculated by ANSYS. Results The stress intensity factor suddenly and continuously decreased in dentino-enamel junction as the crack extended. A large skewed angle appeared, and the stress on crack tip was reduced. Conclusion The dentino-enamel junction on human teeth may resist crack propagation through stress reduction.
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