仿真“骨小梁”牙种植体的生物力学特征

Biomechanical features of trabecular metal dental implants

背景:有研究报道,骨小梁金属可为新生骨组织提供足够的生理支持,使得骨长入、骨整合形成生物性骨结合,有利于提高种植体的初期和二期稳定性。目的:利用三维有限元对比分析多孔钽骨小梁牙种植体和常规钛种植体在下颌双尖牙区不同骨质条件下的应力分布差异。方法:利用Mimics16.0、CATIA等软件建立多孔钽骨小梁牙种植体(实验组)和常规钛牙种植体(对照组),分别在下颌双尖牙区Ⅱ、Ⅲ、Ⅳ类骨质条件下的三维有限元模型,于基台中心颊舌向45°行100 N静力加载,采用MSC Patran和MSC Nastran计算并随机采集具有代表性的冯·米斯应力(Von Mises Stress),SPSS20.0统计软件分析Von Mises Stress分布差异。结果与结论:(1)两组种植体周围Von Mises Stress均集中于骨皮质-种植体-基台连接区域,对应骨松质区应力较小;(2)相同骨质条件下,实验组周围Von Mises Stress平均值大于对照组,但差异无显著性意义;随着骨密度(Ⅱ-Ⅳ)的降低,两种植体周围Von Mises Stress平均值均增大;(3)结果表明多孔钽骨小梁与钛种植体应力大小及分布无显著差异,但随骨密度的降低,多孔钽骨小梁种植体周围应力增大率在Ⅲ-Ⅳ类骨质时小于钛种植体,提示多孔钽骨小梁种植体可能更有利于Ⅲ-Ⅳ骨质疏松患者种植修复后的二期稳定性。

BACKGROUND： Trabecular metal has been reported to provide enough physiologic support for new bone formation, to induce bone ingrowth and osseointegration so as to achieve the biological synosteosis; therefore, it is available for improving the initial and second stability of the dental implant.OBJECTIVE： To explore the stress distributional differences between porous tantalum trabecular metal （PTTM） dental implant and conventional titanium （TI） dental implant in the zone of mandibular premolar using three-dimensional finite element analysis.METHODS： Three-dimensional finite element models emulating PTTM and TI dental implants were established using Mimics16.0 and CATIA in the zone of mandibular premolar with three types of bone （II, III, IV）. Then 100 N force was applied on the abutment at a 45° angle to the vertical axis of the implants in software of MSC Patran2010 and Nastran2010, then the representative von Mises stress nodes were calculated and sampled randomly, and finally the von Mises stress distributional differences between two types of implants were analyzed using SPSS 20.0 statistical software.RESULTS AND CONCLUSION： （1） The Von Mises stresses around the two types of implants both focused on the interface of the cortical bone-abutment-implant region, and the stress was relatively less for the corresponding trabecular bone. （2） If the bone quality was similar, the average von Mises stress of PTTM was higher than that of TI dental implants, but there was no significant difference （P 〉 0.05）. As the bone density lowered （II-IV）, the average Von Mises stresses were both increased, and the increasing rate of PTTM was higher than that of TI in bone of II-III, and was lower than that of TI in bone of III-IV. In this experiment, there were no significant stress distributional differences between PTTM and TI dental implant. However, with the bone density reduction, the increasing rate of average Von Mises stress for PTTM was lowered than that for TI dental implants in bone of III-IV, which suggests that PTTM dental implant may be more beneficial for the primary and secondary stability in osteoporosis patients undergoing dental implantation.