天然牙-种植体联合支持式义齿的应力分析

目的:比较以常规固定桥、固定式套筒冠和CEKA冠外精密附着体为上部结构的天然牙-种植体联合支持义齿的应力分布情况,寻求联合支持义齿上部结构的优化设计方案。方法:利用ANSYS三维有限元法,建立下颌右侧第一磨牙缺失、以下颌第二前磨牙和种植体(位于下颌第二磨牙)联合支持局部固定义齿的三维有限元模型,采用分散垂直和分散斜向(45°)两种加载方式(总加载力200N)。结果:2种加载条件下,固定式套筒冠和CEKA附着体都明显降低了种植体和天然牙周围骨组织的应力,垂直加载时,前者应力值低于后者;斜向加载时,后者低于前者,但后者会使天然牙局部应力有所增加。斜向加载时,种植体及其周围骨组织和天然牙及其周围骨组织的应力值均大于垂直加载条件下的应力值。结论:固定式套筒冠和CEKA附着体均能改善联合支持义齿的应力分布,CEKA附着体对侧向力的缓冲作用较优。

Study on the stress distribution of different superstructures for tooth-implant supported denture

PURPOSE: To compare the stress distributions of fixed bridge, cement-retained telescopic prostheses and extracoronal precision attachment (CEKA attachment) when connect the implants to the natural teeth, in order to find a more suitable design for it. METHODS: 3-D finite element models of tooth-implant partial fixed dentures were constructed by using the ANSYS software. The partial fixed denture was supported by the second premolar and an implant (substitute the second molar). A total load of 200N was distributed to the three units of the denture in vertical and lateral (45 degree) directions. RESULTS: Both of the cement-retained telescopic and the CEKA attachment made the stress of the osseous tissues surrounding the implant and the tooth declined obviously under the loads of the two directions. The stress of the cement-retained telescopic was lower under vertical load,the stress of Ceka attachment was lower under lateral load while it caused the stress of the natural tooth increasing slightly.The stress under the lateral load was higher than that under the vertical load. CONCLUSION: Both of the cement-retained telescopic and the CEKA attachment can improve the stress distribution of tooth-implant support denture. The CEKA attachment is better under lateral loads.