Lin Chun-Li, Chang Shih-Hao, Wang Jen-Chyan
Department of Mechanical Engineering, Chang Gung University, Taoyuan, Taiwan.
Chang Gung Med J. 2006 Mar-Apr;29(2):143-53.
The splinting of an implant and tooth is a rational alternative in some clinical situations. The complex biomechanical aspects of a tooth-implant system are derived from the dissimilar mobility between the osseointegrated implant and the tooth. The aim of this study was to analyze the biomechanics in a tooth-implant splinting system for various bone qualities with different occlusal forces using non-linear finite element (FE) analysis.
A 3D FE model containing one Frialit-2 implant splinted to the mandibular second premolar and a simplified bony segment was constructed. Four bone quality categories were established by varying the elastic parameters assigned to the bone volumes. Contact elements (frictional surface) were used to simulate the realistic frictional interface condition within the implant system. The stress distributions in the splinting system were observed for four loading types.
The simulated results indicated that the lateral occlusal forces significantly increased the implant system (sigmaI, max), alveolar bone (sigmaAB, max) and prosthesis (sigmaP, max) stress values when compared with the axial occlusal forces. The sigma1, max and sigmaP, max values did not exhibit significant differences between the four bone qualities. Conversely, the sigmaAB, max values increased with reduction in bone quality, in particular for type IV bone quality. The sigmaI, max, sigmaAB, max and sigmaP, max stress values were significantly reduced in centric or lateral contact situations once the occlusal forces on the pontic were decreased.
This study suggests that implants connected to natural teeth should be used with caution in softer bone regions. Utilizing occlusal adjustment to minimize the occlusal loading force on the pontic could reduce the stress/strain values in the splinting system.
在某些临床情况下，将种植体与牙齿进行夹板固定是一种合理的选择。牙种植体系统复杂的生物力学特性源于骨结合种植体与牙齿之间不同的移动性。本研究的目的是使用非线性有限元（FE）分析，分析不同骨质量和不同咬合力作用下牙种植体夹板固定系统的生物力学。
构建一个包含一个与下颌第二前磨牙夹板固定的Frialit-2种植体和一个简化骨段的三维有限元模型。通过改变赋予骨体积的弹性参数建立了四种骨质量类别。使用接触单元（摩擦表面）模拟种植体系统内实际的摩擦界面情况。观察四种加载类型下夹板固定系统中的应力分布。
模拟结果表明：与轴向咬合力相比，侧向咬合力显著增加了种植体系统（σI，max）、牙槽骨（σAB，max）和修复体（σP，max）的应力值。σ1，max和σP，max值在四种骨质量之间未表现出显著差异。相反，σAB，max值随骨质量降低而增加，尤其是IV型骨质量。一旦桥体上的咬合力降低，在正中或侧向接触情况下，σI，max、σAB，max和σP，max应力值会显著降低。
本研究表明，在较软的骨区域使用与天然牙相连的种植体时应谨慎。通过咬合调整以最小化桥体上的咬合加载力，可以降低夹板固定系统中的应力/应变值。
