Akhlaghi Pedram, Khorshidparast Setareh, Rouhi Gholamreza
Faculty of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran.
Faculty of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran.
J Mech Behav Biomed Mater. 2023 Oct;146:106062. doi: 10.1016/j.jmbbm.2023.106062. Epub 2023 Aug 3.
Primary stability of a dental implant is defined as its ability to resist the applied load without showing excessive damage in peri-implant bone, which is a prerequisite for secondary stability, and consequently for implantation success. The main goal of this study was to develop a validated micro-finite element (μFE) approach to assess the primary stability of dental implants in terms of stiffness, stiffness reduction, and irreversible displacement of the bone-implant system, subjected to an increasing step-wise quasi-static compressive loading-unloading test. The μFE models were generated based on the μCT images of bone, taken from extracted bovine tibia trabecular bone samples after drilling and implantation. A tissue constitutive model was considered for trabecular bone by describing elasto-plasticity with a modified von Mises yield criterion and element deletion technique to account for trabecular bone damage behavior. Then, the obtained force-displacement curves from the simulation were compared with the in-vitro mechanical test curves to evaluate the validity of the model. The results showed that the proposed μFE model could be properly predict the bone-implant system mechanical response in terms of irreversible displacement (R = 0.99), stiffness (R = 0.77), and stiffness reduction (R = 0.72) of the bone-implant construct for all the applied displacements without a significant difference from the unit slope and zero intercept of the QQ-plot (p-value<0.05). Moreover, a qualitative agreement was seen between the peri-implant bone damage predicted by the μFE model and the observed from μCT images. The adopted methodology used in this study can predict the mechanical failure response of the bone-implant system, which can be employed as a representative tool to study the effects of various dental implant design parameters on the primary stability with the ultimate goal of optimizing dental implants design.
牙种植体的初期稳定性定义为其在种植体周围骨组织中不出现过度损伤的情况下抵抗施加负荷的能力，这是二期稳定性的前提条件，也是种植成功的前提条件。本研究的主要目的是开发一种经过验证的微观有限元（μFE）方法，通过逐步增加的准静态压缩加载-卸载试验，从骨-种植体系统的刚度、刚度降低和不可逆位移方面评估牙种植体的初期稳定性。μFE模型是基于取自钻孔和植入后提取的牛胫骨小梁骨样本的骨μCT图像生成的。通过用修正的冯·米塞斯屈服准则描述弹塑性和采用单元删除技术来考虑小梁骨损伤行为，从而为小梁骨考虑一种组织本构模型。然后，将模拟得到的力-位移曲线与体外力学试验曲线进行比较，以评估模型的有效性。结果表明，所提出的μFE模型能够在所有施加位移下，就骨-种植体结构的不可逆位移（R = 0.99）、刚度（R = 0.77）和刚度降低（R = 0.72）而言，正确预测骨-种植体系统的力学响应，与QQ图的单位斜率和零截距无显著差异（p值<0.05）。此外，μFE模型预测的种植体周围骨损伤与μCT图像观察到的损伤之间存在定性一致性。本研究采用的方法可以预测骨-种植体系统的机械失效响应，可作为一种代表性工具，用于研究各种牙种植体设计参数对初期稳定性的影响，最终目标是优化牙种植体设计。
