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目的分析不同的粘固剂厚度对上颌中切牙桩核冠修复后剩余牙本质和粘固剂应力状况的影响。方法采用三维有限元分析方法,建立不同粘固剂厚度的上颌中切牙桩核冠修复的三维有限元模型,模拟前伸和正中加载,选取指标为Von Mises应力、最大主应力和剪切力,分析粘固剂层厚度变化对牙本质和粘固剂的应力分布以及应力峰值的影响。结果随着粘固剂层的增厚,各模型牙本质应力分布基本相似,前伸加载时3个模型牙本质内Von Mises应力和最大主应力集中区均在根尖,正中加载时两种应力的集中区同时出现在舌侧颈缘及根颈1/3;牙本质内Von Mises应力和最大主应力的峰值略有减小,而粘固剂层的Von Mises应力峰值、最大主应力峰值以及剪切应力峰值均明显减小,其中在前伸加载、粘固剂厚度为100μm时粘固剂层XY和YZ方向剪切应力峰值下降最为明显,分别达到了63.22%和51.46%。结论粘固剂的厚度变化对牙本质的应力影响较小,而对粘固剂本身影响较大,适当增加粘固剂的厚度可以降低粘固剂的应力峰值。
Objective To analyze the effect of different cement thickness on the stress state of residual dentin and cement after the restoration of the maxillary central incisor. Methods The three-dimensional finite element model of the maxillary central incisor restored with different cement thickness was established by three-dimensional finite element analysis. The pre-extension and median-fill were simulated. The selected parameters were Von Mises stress, maximum principal stress and shear force Shear force, the influence of the thickness of cement layer on the stress distribution and stress peak of dentin and cement was analyzed. Results With the thickening of the cement layer, the dentin stress distribution of each model was similar. The Von Mises stress and the maximum principal stress concentration in the dentin were The stress concentrated zone appeared at the lingual side of the neck and the root of the neck 1/3; dentin peak Von Mises stress and maximum stress decreased slightly, while the cement layer Von Mises stress peak, the maximum principal stress Peak value and shear stress peak decreased obviously. When the thickness of the cement was 100μm, the peak shear stress in the XY and YZ direction of the cement was the most obvious, reaching 63.22% and 51.46% respectively. Conclusion The change of cement thickness has little effect on dentin stress, but has a great influence on cement itself. Appropriately increasing the thickness of cement can reduce the stress peak of cement.