不同冠根比平台转换结构种植义齿应力分布三维有限元分析

A finite element analysis of the stress distribution in platform switching configuration implants with different crown root ratios

目的比较不同冠根比的平台转换结构种植义齿对种植体及其周围骨组织应力分布及应力变化趋势的影响。方法建立平台转换结构种植义齿修复下颌第一磨牙的三维有限元模型。将种植体与基台、基台与螺钉、螺钉与种植体之间设置为摩擦接触,摩擦系数为0.3。冠根比分别为1∶1.5、1∶1、1.5∶1、2∶1和3∶1。分别进行垂直向及斜向加载,运用Ansys Workbench 14.0分析比较各组模型Von Mises应力峰值分布情况及应力变化趋势。结果垂直加载下不同冠根比的各组模型整体应力分布较为均匀,Von Mises应力峰值变化不明显。当冠根比为1.5∶1时,种植体颈部出现最大应力值。应力集中区出现在种植体颈部与基台及基台与中央螺丝连接处;斜向载荷下,随着冠根比的增大,各组模型Von Mises应力峰值明显增大,冠根比为3∶1时种植体和中央螺丝的应力峰值约为1∶1时的3倍,其余部件约增大1倍。应力集中区与垂直载荷下相一致,但Von Mises最大应力出现在基台上。结论在摩擦接触条件下,平台转换结构能够有效地转移种植体的应力集中区,减少牙槽骨吸收。在冠根比较大时,应采取有效措施减小义齿斜向受力。

Objective ratios on the distribution and changing trend of stress in implants and the surrounding bone.MethodsEstablish th three-dimensional finite element model of platform switching configuration implant for the repair of mandibular first mo lar. The contact relationship between implant and abutment,abutment and screws,screws and implants was set for fric tional contact,and 0.3 was taken as the friction coefficient. Ansys Workbench 14.0 software was used to analyse and com pare the distribution of Mises Von maximum stress and the trend of the stress change in different models under vertical o oblique loading. The crown root ratio of the implants was 1∶1.5,1∶1,1.5∶1,2∶1 and 3∶1 respectively.ResultsUnde the vertical loading,the stress distribution of the models with different crown root ratio was more uniform and the chang of Mises Von maximum stress was not obvious. When the crown root ratio was 1.5∶1,the maximum stress value appeare in the neck of the implant. Stress concentration zones appeared in the connection between neck of implant and abutmentscrew connections. Under the oblique loading,with the increases of crown root ratio,the Mises Von maximum stress of each model increased significantly.When the crown root ratio was 3∶1,the stress peak of the implant and the central screw was nearly three-fold of that of 1∶1,and the stress peak of therest components almost doubled. The stress concentration area was consistent with the vertical loading,but the maximum Mises Von stress appeared in the abutment.ConclusionUnder the condition of frictional contact,the platform switching configuration can effectively transfer the stress concentration area of the implant,and then reduce the absorption of the alveolar bone. At the same time,when the crown root ratio is relatively large,the effective measures should be taken to reduce the oblique stress of the denture.