摘要
目的 研究种类和强度不同的冠预备体材料与瓷层破折碎裂的内在关系 ,对临床上残根、残冠的核桩冠修复技术以及全冠的修复技术提供必要的理论指导。方法 选用计算机建立上颌牙的三维有限元模型 ,模拟了瓷层、Ni-Cr合金帽状冠、牙本质、核桩等结构 ,与临床实际结构类似。分析在活髓牙、钴铬合金及复合树脂三种预备体情况下 ,金属烤瓷全冠的瓷层内、金瓷界面以及残余牙本质的应力分布情况。结果 高弹性模量的Co -Cr合金能够降低瓷层、金瓷界面以及残余牙本质内的最大主应力和最小主应力峰值 ,防止瓷层破折碎裂 ,同时 ,改变原有的应力分布模式 ,在桩与残余牙本质交界处出现应力集中现象 ,而弹性模量与牙本质基牙相近的复合树脂桩不改变原有的应力分布模式 ,降低应力峰值的作用不明显。结论 对于行根充治疗术的无髓牙 ,应采用高弹性模量的高熔合金核桩冠修复 ;对于活髓牙 ,保存牙髓活力行烤瓷冠修复。
Objective To investigate the relationship between different kinds and strengths of preparation and the fragmentation of porcelain which may assist to improve the design of the post-core crown and full crown.Methods A three-dimensional finite element model of maxillary incisor which consisted of porcelain,Ni-Cr metal crown,post-core,similar to the clinical structure,was constructed by means of Super SAP on a personal computer.We analyzed the tensile stress distributions on the crown and residual dentin under three kinds of preparation which were a natural tooth,a Co-Cr cast core and a composite resin core.Results Co-Cr metal post core with high elastic modules decreased the maximum principle stress and minimum principle stress on porcelain,interface of porcelain and metal and residual dintin,then preventing the fragmentation of porcelain.Meanwhile,this design changed the pattern of stress distribution,with high stress concentrating on the border between post and dentin.The stress distribution pattern of the composite resin post core with low elastic modules was similar to that of natural tooth,but had little influence in lessening the principle stress.Conclusion For natural tooth preparation with active pulp,we should make full crown and preserve the activity of pulp.For post-core crown,we should use metal post core with high elastic modules to avoid using resinpost core with low elastic modules.
出处
《现代口腔医学杂志》
CAS
CSCD
2002年第2期163-165,共3页
Journal of Modern Stomatology
