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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 To compare the effect of implant dentures with different crown-root ratio on the stress distribution and stress trend of implant and surrounding bone. Methods The three-dimensional finite element model of the mandibular first molar restored with implant-implant system was established. The implant and abutments, abutments and screws, screws and implants placed between the frictional contact, the friction coefficient of 0.3. The crown-root ratio was 1: 1.5, 1: 1, 1.5: 1, 2: 1 and 3: 1, respectively. The vertical and diagonal loads were applied respectively. The distribution of stress Von Mises stress and the trend of stress change were analyzed by Ansys Workbench 14.0. Results The stress distribution of the groups with different crown-root ratios under vertical loading was more uniform and the Von Mises stress peak did not change significantly. When the crown-root ratio is 1.5: 1, the maximum stress appears on the neck of the implant. Stress concentration zone appeared in the implant neck and abutments and abutments and the central screw connection Department; oblique load, with the crown-root ratio increases, the model Von Mises stress peak value increased significantly, the crown-root ratio At 3: 1, the stress peak of the implant and the central screw is about 3 times the peak at about 1: 1, with the remaining components about a factor of 1. The stress concentration zone is consistent with the vertical load, but the maximum Von Mises stress appears on the abutment. Conclusion Under the condition of frictional contact, the platform transfer structure can effectively transfer stress concentration area of implants and reduce alveolar bone resorption. When the crown-root ratio is relatively large, effective measures should be taken to reduce the oblique force of the denture.