Valente Mariana Lima da Costa, de Castro Denise Tornavoi, Macedo Ana Paula, Shimano Antonio Carlos, Dos Reis Andréa Cândido
Department of Dental Materials and Prosthesis, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Av. do Café, s/n°, 14040-904 Ribeirão Preto, SP, Brazil.
Department of Dental Materials and Prosthesis, School of Dentistry of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Av. do Café, s/n°, 14040-904 Ribeirão Preto, SP, Brazil.
Mater Sci Eng C Mater Biol Appl. 2017 Aug 1;77:360-365. doi: 10.1016/j.msec.2017.03.268. Epub 2017 Mar 29.
The purpose of this study was to compare, through photoelastic analysis, the stress distribution around conventional and modified external hexagon (EH) and morse taper (MT) dental implant connections. Four photoelastic models were prepared (n=1): Model 1 - conventional EH cylindrical implant (Ø 4.0mm×11mm - Neodent®), Model 2 - modified EH cylindrical implant, Model 3 - conventional MT Conical implant (Ø 4.3mm×10mm - Neodent®) and Model 4 - modified MT conical implant. 100 and 150N axial and oblique loads (30° tilt) were applied in the devices coupled to the implants. A plane transmission polariscope was used in the analysis of fringes and each position of interest was recorded by a digital camera. The Tardy method was used to quantify the fringe order (n), that calculates the maximum shear stress (τ) value in each selected point. The results showed lower stress concentration in the modified cylindrical implant (EH) compared to the conventional model, with application of 150N axial and 100N oblique loads. Lower stress was observed for the modified conical (MT) implant with the application of 100 and 150N oblique loads, which was not observed for the conventional implant model. The comparative analysis of the models showed that the new design proposal generates good stress distribution, especially in the cervical third, suggesting the preservation of bone tissue in the bone crest region.
本研究的目的是通过光弹性分析比较传统和改良型外六角（EH）及莫氏锥度（MT）牙种植体连接周围的应力分布。制备了四个光弹性模型（n = 1）：模型1 - 传统EH圆柱形种植体（Ø 4.0mm×11mm - Neodent®），模型2 - 改良EH圆柱形种植体，模型3 - 传统MT锥形种植体（Ø 4.3mm×10mm - Neodent®）和模型4 - 改良MT锥形种植体。在与种植体相连的装置上施加100N和150N的轴向及斜向载荷（30°倾斜）。使用平面透射偏光镜分析条纹，并通过数码相机记录每个感兴趣的位置。采用塔尔迪方法量化条纹级数（n），该方法计算每个选定点的最大剪应力（τ）值。结果显示，在施加150N轴向和100N斜向载荷时，改良圆柱形种植体（EH）的应力集中低于传统模型。在施加100N和150N斜向载荷时，改良锥形（MT）种植体的应力较低，而传统种植体模型未观察到这种情况。模型的对比分析表明，新的设计方案能产生良好的应力分布，尤其是在颈部三分之一处，这表明骨嵴区域的骨组织得以保留。
