Jin Xiao-Zhuang, Homaei Ehsan, Matinlinna Jukka Pekka, Tsoi James Kit Hon
Dental Materials Science, Faculty of Dentistry, The University of Hong Kong, Hong Kong Special Administrative Region, P. R. China.
Dental Materials Science, Faculty of Dentistry, The University of Hong Kong, Hong Kong Special Administrative Region, P. R. China; Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran.
Dent Mater. 2016 Oct;32(10):e238-e250. doi: 10.1016/j.dental.2016.07.005. Epub 2016 Aug 3.
Numerous bond strength tests have been performed on dental adhesion experiments. Yet, the validity of these bond strength tests is controversial due to the name (e.g., "shear" or "tensile") may not reflect to the true and complete stress situation, i.e., assumed uniform shear or uniaxial tensile conditions. Thus, the aim of this study was to simulate and compare the stress distribution of and between shear bond strength (SBS), tensile bond strength (TBS), mold-enclosed shear bond strength (ME-SBS) and de novo lever-induced mold-enclosed shear bond strength (LIME-SBS) tests.
3-Dimensional finite element method (FEM) was used on the dental resin-bonded surfaces (i.e., titanium alloy, dentine and porcelain) interphased with adhesive layer (thickness 5μm) to simulate the mechanical tests. For ME-SBS, both polycarbonate and stainless steel molds were used. For LIME-SBS, stainless steel levers and molds with lengths of 3mm, 6mm, 12mm, 15mm and 18mm were used. The applied loads on these models were 50N, 100N and 200N.
De novo LIME-SBS test was the most optimal configuration to evaluate "shear" bond strength of adhesive in regards to providing significantly high and uniform shear stress as well as eliminating tensile stress at the interface. The conventional SBS test created very high tensile stress at the load area, whereas the TBS created optimal tensile stress but shear stress indeed co-exist. The ME-SBS test could also eliminate some of the tensile stress. Similar stress distributions pattern appeared on the Ti-adhesive models, the dentine-adhesive models and porcelain-adhesive models.
None of the bond strength tests could give purely "shear" or "tensile" bond strength, but LIME-SBS seems to be the best model to evaluate the bond strength under true "shear" mode.
在牙齿黏附实验中已经进行了大量的粘结强度测试。然而，这些粘结强度测试的有效性存在争议，因为其名称（例如，“剪切”或“拉伸”）可能无法反映真实和完整的应力情况，即假定的均匀剪切或单轴拉伸条件。因此，本研究的目的是模拟并比较剪切粘结强度（SBS）、拉伸粘结强度（TBS）、模具封闭剪切粘结强度（ME-SBS）和新型杠杆诱导模具封闭剪切粘结强度（LIME-SBS）测试中以及它们之间的应力分布。
采用三维有限元方法（FEM）对与厚度为5μm的粘结剂层相间的牙齿树脂粘结表面（即钛合金、牙本质和瓷）进行模拟力学测试。对于ME-SBS，使用了聚碳酸酯和不锈钢模具。对于LIME-SBS，使用了长度为3mm、6mm、12mm、15mm和18mm的不锈钢杠杆和模具。这些模型上施加的载荷为50N、100N和200N。
就提供显著高且均匀的剪切应力以及消除界面处的拉伸应力而言，新型LIME-SBS测试是评估粘结剂“剪切”粘结强度的最优化配置。传统的SBS测试在加载区域产生了非常高的拉伸应力，而TBS产生了最佳的拉伸应力，但剪切应力确实同时存在。ME-SBS测试也可以消除一些拉伸应力。在钛-粘结剂模型、牙本质-粘结剂模型和瓷-粘结剂模型上出现了类似的应力分布模式。
没有一种粘结强度测试能够给出纯粹的“剪切”或“拉伸”粘结强度，但LIME-SBS似乎是在真实“剪切”模式下评估粘结强度的最佳模型。
