Soares C J, Soares P V, Santos-Filho P C F, Armstrong S R
Biomechanics group, School of Dentistry, Federal University of Uberlândia, Av. Pará 1720, Bloco 2B, sala 2B24, 38400-902, Uberlândia, MG, Brazil.
J Dent Res. 2008 Jan;87(1):89-93. doi: 10.1177/154405910808700116.
Microtensile bond strength values are influenced by specimen shape and attachment method to the gripping device during testing. We hypothesized that stress distribution inside the testing specimen is affected by microtensile specimen shape and attachment method. Rectangular, hourglass-, and dumbbell-shaped specimens, all with a 1 mm(2) cross-sectional testing region, were modeled as indirect ceramic restorations luted to dentin. Three specimen attachments were investigated: (1) posterior surface; (2) posterior, superior, and lateral surfaces; and (3) all surfaces. Qualitative and quantitative analyses were carried out according to von Mises' criteria. Stress analysis showed a direct correlation between attachment modes and stress distribution, with shear stresses observed in models with less surface attachment. Increasing the number of faces for specimen attachment to the metallic gripping device resulted in a more homogeneous and regular distribution of stress, with tensile stress concentrated at the adhesive interface. Dumbbell-shaped specimens showed improved stress distribution compared with rectangular and hourglass-shaped specimens.
微拉伸粘结强度值在测试过程中受样本形状以及与夹持装置的连接方式影响。我们推测测试样本内部的应力分布受微拉伸样本形状和连接方式的影响。将所有横截面测试区域为1平方毫米的矩形、沙漏形和哑铃形样本模拟为粘结于牙本质的间接陶瓷修复体。研究了三种样本连接方式：（1）后表面；（2）后表面、上表面和侧表面；（3）所有表面。根据冯·米塞斯准则进行定性和定量分析。应力分析表明连接方式与应力分布直接相关，在表面连接较少的模型中观察到剪应力。增加样本与金属夹持装置连接的面数会使应力分布更均匀、规则，拉应力集中在粘结界面处。与矩形和沙漏形样本相比，哑铃形样本的应力分布有所改善。
