Objectives

The aim of this study was to investigate dentin bonding durability of different etch-and-rinse (ER) adhesive systems under fatigue stress and to compare morphological features of resin/dentin interfaces using SEM.

Methods

Two three-step ER adhesives, a two-step ER adhesive, and a universal adhesive in ER mode were evaluated. Before application of either primer or adhesive, phosphoric acid etching of human dentin was completed. Fifteen bonded specimens for each adhesive system were stored in distilled water at 37 °C for 24 h, then subjected to a shear bond strength (SBS) test. Bonding durability was assessed from the perspective of biomechanical stress. 25 bonded specimens for each adhesive system were subjected to shear fatigue strength (SFS) testing with a repeated subcritical load at a frequency of 20 Hz for 50,000 cycles or until failure.

Results

Mean SBS and SFS values ranged from 33.3 to 41.2 MPa, and from 18.3 to 20.3 MPa, respectively. Three-step adhesives showed higher SBS and SFS values than the other adhesive systems. Under SEM, resin tags in different adhesive systems showed similar features, but morphology below the hybrid layer was material dependent. The universal adhesive in ER mode showed an obvious thin, high-density reaction layer below the hybrid layer.

Significance

Three-step adhesives showed higher dentin bond durability than the other ER adhesives; no significant differences in SFS were found between the universal adhesive in ER mode and the three-step ER adhesives. The results of this in vitro study indicate that some ER adhesives might establish chemical bonding with intact dentin below the hybrid layer in addition to micromechanical retention.

中文翻译：

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基于剪切疲劳牙本质粘合强度和界面形态特征的不同蚀刻和冲洗粘合剂体系的比较

目标

这项研究的目的是研究在疲劳应力下不同蚀刻和冲洗（ER）粘合剂体系的牙本质粘合耐久性，并使用SEM比较树脂/牙本质界面的形态特征。

方法

评估了两种三步ER粘合剂，两步ER粘合剂和处于ER模式的通用粘合剂。在施加底漆或粘合剂之前，已完成对人牙本质的磷酸蚀刻。将每种粘合剂体系的15个粘合样品在37°C的蒸馏水中保存24小时，然后进行剪切粘合强度（SBS）测试。从生物力学应力的角度评估粘合耐久性。对每个粘合剂体系的25个粘合样品进行剪切疲劳强度（SFS）测试，并在20 Hz的频率下反复施加次临界载荷5万次，直至失效。

结果

SBS和SFS的平均值分别为33.3至41.2 MPa和18.3至20.3 MPa。三步胶粘剂显示出比其他胶粘剂系统更高的SBS和SFS值。在SEM下，不同胶粘剂系统中的树脂标签显示出相似的特征，但杂化层下方的形态取决于材料。ER模式下的通用胶粘剂在杂化层下方显示出明显的薄而高密度的反应层。

意义

三步胶粘剂显示出比其他ER胶粘剂更高的牙本质粘合耐久性。在ER模式的通用胶粘剂和三步ER胶粘剂之间，在SFS上没有发现显着差异。这项体外研究的结果表明，除了微机械固位力外，某些ER粘合剂还可能与杂化层下方的完整牙本质建立化学键合。