新型医用锆合金静力加载有限元研究

Finite Element Study on Static Loading of New Medical Zirconium Alloys

摘要:

采用有限元方法探究材料弹性模量对种植体及骨组织应力应变分布的影响，同时根据牙科制造商和临床统计数据，建立种植体和下颌骨模型；通过拉伸试验获得制备的Zr30Ti、Zr22Nb相关材料参数，并选择弹性模量为110 GPa的Ti6Al4V和30 GPa的Zr24Nb作为对比；骨组织采用更接近真实特性的正交异性材料模型；施加垂直和倾斜载荷，根据ISO14801标准，倾斜角度为30°。研究均以Ti6Al4V为参照，结果表明：种植体弹性模量降低对其在倾斜载荷下的承载能力不利，Zr30Ti（76 GPa）、Zr22Nb（59 GPa）、Zr24Nb（30 GPa）的应力增幅分别为2.98%、5.47%、14.55%，但最大应力仍小于其强度（分别为952、611、800 MPa）。种植体传递的应力主要由皮质骨承担，倾斜载荷下Zr30Ti、Zr22Nb、Zr24Nb在皮质骨中产生的最大应力增幅分别为17.59%、31.92%、79.14%，皮质骨过载风险随种植体弹性模量降低而增加，但其中Zr30Ti、Zr22Nb在皮质骨中产生的应力仍小于皮质骨强度，具有良好的应用安全性。种植体向皮质骨传递的应力随弹性模量的降低数值增大且更为均匀，倾斜载荷下Zr30Ti、Zr22Nb、Zr24Nb在种植体-骨界面的皮质骨平均Mises应力增幅分别为12.75%、122.94%、155.11%，界面上种植体-骨的应力差降低幅度分别为16.82%、29.45%、65.41%。弹性模量较低的种植体内部变形区较大，倾斜载荷下Zr30Ti、Zr22Nb、Zr24Nb种植体颈部的内部最大应变分别是Ti6Al4V的2倍、2.6倍、4.9倍，且与骨组织模量差较小，种植体和皮质骨在界面处的变形更协调，从而促进应力向皮质骨传递，减小界面应力差。随着弹性模量的降低，松质骨植入位置底部的应力逐渐减小、整体应力向上部集中，Zr30Ti、Zr22Nb锆合金种植体的松质骨应力分布更为均匀。

Abstract:

The effect of material elastic modulus on stress and strain distribution in implants and bone tissue was investigated. Utilizing dental manufacturer and clinical statistical data, implant and mandible bone models were established. Material parameters for prepared Zr30Ti and Zr22Nb alloys were obtained through tensile testing, with Ti6Al4V (elastic modulus: 110 GPa) and Zr24Nb (elastic modulus: 30 GPa) selected as contrasting materials. Bone tissue was modeled using orthotropic material properties closer to real characteristics. Vertical and oblique loads were applied according to ISO 14801 standards, with a tilt angle of 30°. All studies were referenced against Ti6Al4V. Results show that the decrease in implant elastic modulus detrimentally affects its load-bearing capacity under oblique loads, with stress increments for Zr30Ti (76 GPa), Zr22Nb (59 GPa), and Zr24Nb (30 GPa) of 2.98%, 5.47%, and 14.55%, respectively. However, maximum stresses still remain below their strengths (952, 611, and 800 MPa). The stress transmission from implants is primarily borne by cortical bone, with maximum stress increments in cortical bone under oblique loads for Zr30Ti, Zr22Nb, and Zr24Nb of 17.59%, 31.92%, and 79.14%, respectively. The risk of cortical bone overloading increases with decrease in implant elastic modulus, but the stresses generated by Zr30Ti and Zr22Nb within cortical bone remain below cortical bone strength, ensuring favorable application safety. The stress transmitted from implants to cortical bone increases and becomes more uniform with decrease in elastic modulus, with average Mises stress increments at the implant-bone interface for Zr30Ti, Zr22Nb, and Zr24Nb under oblique loads of 12.75%, 122.94%, and 155.11%, respectively; while the stress difference at the interface for implant-bone decreases by 16.82%, 29.45% and 65.41%, respectively. This is attributed to larger deformation zones within implants with lower elastic modulus, where under oblique loads, the internal maximum strains in the neck region of Zr30Ti, Zr22Nb, and Zr24Nb implants are 2 times, 2.6 times, and 4.9 times greater than that of Ti6Al4V, respectively, with minimal differences in modulus between implants and bone tissue, promoting more coordinated deformation at the interface. Thereby, this can promote stress transfer to cortical bone and reduce interfacial stress difference. With decrease in elastic modulus, the stress at the bottom of cancellous bone implant sites gradually decreases, and the overall stress is concentrated in the upper part. The stress distribution of the cancellous bone in Zr30Ti and Zr22Nb zirconium alloy implants is more uniform.