AIM To analyse the effect of post-core, and cement materials and thickness of the cement lute on the stress in post-core systems under ultrasonic vibration at different frequencies and amplitudes using three-dimensional finite element analysis. METHODOLOGY Eight three-dimensional finite element models of a maxillary central incisor with post-cores were established. Two post-core materials (Au and Ni-Cr alloys), two cements (glass ionomer (GI) and zinc phosphate (ZP)) and two cement layer thicknesses (50 and 150 μm) were considered. Vibration loads were applied near the neck on the buccal side of the core at frequencies of 10-40 kHz and amplitudes of 10-50 μm. The maximum shear stress of the cement layer and maximum principal stress of the roots and their distributions were investigated. RESULTS The stresses on cements and roots increased with an increase in the frequency and amplitude of the vibration load and elastic modulus of the cements, and decreased with increasing thickness of the cement layer and elastic modulus of the post-core. Maximum cement stress was observed on the contralateral upper part of the loading side, whereas the maximum root stress was found on the ferrule where the load was applied. CONCLUSIONS In this simulated model, the frequency and amplitude of ultrasound needed to remove a post-core were positively related to the elastic modulus of the post-core and thickness of the cement layer and negatively related to the elastic modulus of the cements.

中文翻译：

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桩芯材料和水泥特性对超声波振动下桩芯应力的影响：三维有限元分析。

目的利用三维有限元分析方法，分析不同频率和振幅的超声振动下桩芯，水泥材料和水泥屑厚度对桩芯系统应力的影响。方法建立了带有后核的上颌中切牙的八个三维有限元模型。考虑了两种后核材料（Au和Ni-Cr合金），两种水泥（玻璃离聚物（GI）和磷酸锌（ZP））和两种水泥层厚度（50和150μm）。在芯的颊侧颈部附近以10-40 kHz的频率和10-50μm的振幅施加振动载荷。研究了水泥层的最大剪切应力和根部的最大主应力及其分布。结果水泥和根系上的应力随水泥的振动载荷频率和振幅，弹性模量的增加而增加，随水泥层厚度和后芯厚度的增加而减小。在载荷侧的对侧上部观察到最大水泥应力，而在施加载荷的套圈上发现最大根应力。结论在该模拟模型中，去除后岩心所需的超声波的频率和幅度与后岩心的弹性模量和水泥层的厚度呈正相关，与水泥的弹性模量呈负相关。随着水泥层厚度的增加和后岩心的弹性模量的增加而降低。在载荷侧的对侧上部观察到最大水泥应力，而在施加载荷的套圈上发现最大根应力。结论在该模拟模型中，去除后岩心所需的超声频率和振幅与后岩心的弹性模量和水泥层的厚度呈正相关，与水泥的弹性模量呈负相关。随着水泥层厚度的增加和后岩心的弹性模量的增加而降低。在载荷侧的对侧上部观察到最大水泥应力，而在施加载荷的套圈上发现最大根应力。结论在该模拟模型中，去除后岩心所需的超声频率和振幅与后岩心的弹性模量和水泥层的厚度呈正相关，与水泥的弹性模量呈负相关。