Koosha Sara, Mirhashemi Fatemeh Sadat
Assisstant Professor, Department of Prosthodontics, Islamic Azad University of Medical Science, Branch of Dentistry, Tehran, Iran.
J Dent (Tehran). 2013 Jan;10(1):51-63. Epub 2013 Jan 31.
Tooth/implant supported fixed prostheses may present biomechanical design problems, as the implant is rigidly anchored within the alveolus, whereas the tooth is attached by the periodontal ligament to the bone allowing movement. Many clinicians prefer tooth/implant supported fixed prosthesis designs with rigid connectors. However, there are some doubts about the effect of attachment placement in different prosthesis designs. The purpose of this study was to examine the stresses accumulated around the implant and natural teeth under occlusal forces using three dimensional finite element analysis (3D FEA).
In this study, different connection designs of tooth/implant fixed prosthesis in distal extension situations were investigated by 3D FEA. Three models with various connection designs were studied; in the first model an implant rigidly connected to an abutment, in the second and third models an implant connected to abutment tooth with nonrigid connector in the distal part of the tooth and mesial part of the implant. In each model, a screw type implant (5×11mm) and a mandibular second premolar were used. The stress values of these models loaded with vertical forces (250N) were analyzed.
There was no difference in stress distribution around the bone support of the implant. Maximum stress values were observed at the crestal bone of the implant. In all models, tooth movement was higher than implant movement.
There is no difference in using a rigid connector, non rigid connector in the distal surface of the tooth or in the mesial surface of an implant.
牙/种植体支持的固定修复体可能存在生物力学设计问题，因为种植体牢固地锚固在牙槽骨内，而牙齿通过牙周韧带与骨相连，允许移动。许多临床医生更喜欢采用刚性连接体的牙/种植体支持的固定修复体设计。然而，对于不同修复体设计中连接体位置的影响存在一些疑问。本研究的目的是使用三维有限元分析（3D FEA）来研究在咬合力作用下种植体和天然牙周围积累的应力。
在本研究中，通过3D FEA研究了远中游离端情况下牙/种植体固定修复体的不同连接设计。研究了三种具有不同连接设计的模型；在第一个模型中，种植体与基牙刚性连接，在第二个和第三个模型中，种植体在牙齿远中部分和种植体近中部分通过非刚性连接体与基牙相连。在每个模型中，使用了一个螺钉型种植体（5×11mm）和一颗下颌第二前磨牙。分析了这些模型在垂直力（250N）加载下的应力值。
种植体骨支持周围的应力分布没有差异。在种植体的牙槽嵴顶骨处观察到最大应力值。在所有模型中，牙齿的移动高于种植体的移动。
在种植体近中面、牙齿远中面使用刚性连接体或非刚性连接体没有差异。
