Ismail Ahmed M, ElBanna Ahmed, Nassef Tamer M, Keilig Ludger, Bourauel Christoph
Oral Technology, University Hospital Bonn, Bonn, Germany; Biomaterials Department, Faculty of Dentistry, Ain Shams University, Cairo, Egypt.
Biomaterials Department, Faculty of Dentistry, Ain Shams University, Cairo, Egypt.
Int Dent J. 2025 Jun;75(3):1746-1758. doi: 10.1016/j.identj.2025.03.007. Epub 2025 Apr 5.
The aim of this study was to develop a numerical model for simulating shear bond strength tests with different specimen sizes and loading techniques. A finite element model was generated consisting of a composite specimen bonded to dentin substrate surrounded by enamel, acrylic resin and polypropylene tube. Four models were created simulating macro (diameter 1.8 mm) and micro (0.8 mm) sized specimens loaded by either a chisel or a wire loop. Experimental data from a previously published study using the identical specimen diameter and shearing tools were used as reference. Four groups were established: macro shear wire loop (group 1), micro shear wire loop (group 2), macro shear chisel (group 3), and micro shear chisel (group 4). In the simulations, contact-based glue failure based on shear contact stresses (series 1) or a combination of shear and normal contact stresses (series 2) were used to simulate the progressive failure of the specimens. Shear and normal failure stress limits were fitted to the experimental results in sensitivity analyses by varying both stresses. Experimental failure forces could be reproduced using group-specific shear stress limits of 71 (group 1), 48 (group 2), 106 (group 3), and 131 MPa (group 4) in series 1. However, when also considering normal stresses, no single, unique pair of shear and normal failure stresses can lead to the experimental failure force values for all groups. In conclusion, no unique pair of shear and normal stresses can provide the same failure force values for different shear setup geometries.
本研究的目的是开发一种数值模型，用于模拟不同试件尺寸和加载技术的剪切粘结强度试验。生成了一个有限元模型，该模型由粘结在牙本质基质上的复合试件组成，周围环绕着牙釉质、丙烯酸树脂和聚丙烯管。创建了四个模型，模拟通过凿子或金属丝环加载的宏观（直径1.8毫米）和微观（0.8毫米）尺寸的试件。使用先前发表的一项研究中使用相同试件直径和剪切工具的实验数据作为参考。建立了四组：宏观剪切金属丝环（第1组）、微观剪切金属丝环（第2组）、宏观剪切凿子（第3组）和微观剪切凿子（第4组）。在模拟中，基于剪切接触应力（系列1）或剪切和法向接触应力的组合（系列2）的基于接触的胶水失效被用于模拟试件的渐进失效。在敏感性分析中，通过改变两种应力，将剪切和法向失效应力极限拟合到实验结果。在系列1中，使用71（第1组）、48（第2组）、106（第3组）和131兆帕（第4组）的特定组剪切应力极限可以再现实验失效力。然而，当也考虑法向应力时，没有单一的、独特的一对剪切和法向失效应力能导致所有组的实验失效力值。总之，对于不同的剪切设置几何形状，没有独特的一对剪切和法向应力能提供相同的失效力值。
