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目的::应用三维有限元分析下颌第一磨牙近中邻面缺损情况下不同数量、不同位置纤维桩核冠修复时牙本质的应力。方法:分组方法分别采用近中舌侧根管置入纤维桩1根;近中颊侧根管置入纤维桩1根;近颊、近舌根管各置入纤维桩一根;根管内无纤维桩置入共4组;均采用树脂核及钴铬合金烤瓷全冠修复。测试各组试件在垂直力或45°力加载下Von mises应力和最大拉应力的峰值变化。结果:随着根桩数目的变化,各组之间剩余牙本质上Von mises应力、最大拉应力的应力峰值变化不大。45°方向加载时牙根桩核应力均大于垂直方向加载者,两者具有显著性差异(P<0.05)。应力图显示牙颈部应力稍高,其他区域的应力值较小,分布较均匀,在根管壁上呈现出低应力的分布状态;45°力加载与垂直加载相比,各部位应力明显增高。结论:牙体强度与剩余牙体组织关系密切,剩余牙体组织越少,其承担应力越大,发生牙折的可能性越大,临床上在桩核强度足够的前提下,应尽可能多保存健康的牙体组织,根管尽量少扩大,以减少根管壁的应力,减少牙根折裂的风险。在修复过程中应尽量减少侧向力,采用适当减小牙尖斜度,调磨对颌牙过陡牙尖的方法,以降低侧向力对牙体组织应力大小和分布范围的影响,从而降低牙折风险,提高修复体使用寿命。
OBJECTIVE: To analyze the stress of dentine in different numbers and locations of post-and-core crown restored by three-dimensional finite element analysis of the mandibular first molars. Methods: One group of fiber posts were inserted into the proximal and middle lingual root canal respectively by grouping method. One root of fiber bundle was inserted into the proximal and middle buccal root canal. One fiber bundle was placed near the buccal and proximal lingual canal. Fiber posts into a total of 4 groups; both resin core and cobalt-chromium alloy porcelain crown repair. The peak change of Von mises stress and maximum tensile stress were tested under the normal force or 45 ° load. Results: With the change of the number of root piles, the peak stress of the maximum tensile stress did not change much with Von mises stress on the residual dentin between the groups. At 45 °, the stress of stump core was larger than that of vertical loading, which had significant difference (P <0.05). The stress maps showed slightly higher stress in the cervical and cervical parts, less stress in other regions, more uniform distribution and low stress distribution in the root canal wall. Compared with the vertical loading, Increase. Conclusion: There is a close relationship between the strength of tooth body and the remaining tooth tissue. The smaller the remaining tooth tissue, the greater the burden on the tooth. The more likely it is to have a tooth fracture. Clinically, as long as the core strength is sufficient, Save healthy tooth tissue, root canal enlargement as little as possible to reduce the stress of the root canal wall and reduce the risk of root fracture. In the repair process should minimize the lateral force, the use of appropriate reduction of cusp inclination, grinding the teeth on the tip too sharp tip method to reduce the lateral force on the tooth tissue stress size and distribution of the impact, Thereby reducing the risk of tooth fractures and improve the life of the prosthesis.