OBJECTIVE The aim of this study was to observe the resin/dentin interfaces of universal adhesives by using scanning electron microscopy (SEM), and to compare their morphologies with conventional etch & rinse (ER) and self-etch (SE) adhesive systems. METHODS Two three-step and one two-step ER adhesives and two two-step and two single-step SE adhesives were used for comparison with seven universal adhesives in ER mode and SE mode, respectively. Bonded surfaces with bovine teeth were longitudinally sectioned and mirror-polished. Half of the samples were treated with HCl and NaOCl solutions. The interfaces were subjected to argon ion beam etching and then observed by scanning electron microscopy. RESULTS The thickness of the adhesive layer (AL) of most of the seven universal adhesives and single-step SE adhesives was similar. Universal adhesives in SE mode formed a hybrid smear layer as a high-density zone between the AL and dentin. The thickness of the hybrid layer (HL) of the universal adhesives in ER mode was ∼1-2μm, with a high-density zone (reaction layer [RL]) below the HL. CONCLUSION The morphological features of most universal adhesives in SE mode and single-step SE adhesives are similar. Although resin-dentin interfaces of universal adhesives in ER mode resemble those of ER adhesives, universal adhesives have a distinctive feature, an RL. SIGNIFICANCE The RL might be a sign of chemical bonding even when using universal adhesives in ER mode.

中文翻译：

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SEM观察通用粘合剂牙本质键界面的新特征。

目的本研究的目的是通过使用扫描电子显微镜（SEM）观察通用胶粘剂的树脂/牙本质界面，并将其形态与常规蚀刻和冲洗（ER）和自蚀刻（SE）胶粘剂系统进行比较。方法使用两种三步法和一种两步法ER胶粘剂以及两种两步法和两种单步法SE胶粘剂分别与ER模式和SE模式下的7种通用胶粘剂进行比较。将带有牛齿的粘合表面纵向剖切并镜面抛光。一半样品用HCl和NaOCl溶液处理。对界面进行氩离子束蚀刻，然后通过扫描电子显微镜观察。结果七种通用粘合剂和单步SE粘合剂中大多数的粘合剂层（AL）的厚度相似。SE模式下的通用粘合剂在AL和牙本质之间形成了高密度区域的混合涂抹层。ER模式下通用粘合剂的混合层（HL）的厚度约为1-2μm，在HL下方有一个高密度区域（反应层[RL]）。结论大多数SE模式的通用胶粘剂和单步SE胶粘剂的形态特征相似。尽管通用粘合剂在ER模式下的树脂-牙本质界面类似于ER粘合剂的界面，但通用粘合剂具有鲜明的特征，即RL。意义即使在ER模式下使用通用胶粘剂，RL也可能是化学键合的标志。在HL下方具有高密度区域（反应层[RL]）。结论大多数SE模式的通用胶粘剂和单步SE胶粘剂的形态特征相似。尽管通用粘合剂在ER模式下的树脂-牙本质界面类似于ER粘合剂的界面，但通用粘合剂具有鲜明的特征，即RL。意义即使在ER模式下使用通用胶粘剂，RL也可能是化学键合的标志。在HL下方具有高密度区域（反应层[RL]）。结论大多数SE模式的通用胶粘剂和单步SE胶粘剂的形态特征相似。尽管通用粘合剂在ER模式下的树脂-牙本质界面类似于ER粘合剂，但通用粘合剂具有鲜明的特征，即RL。意义即使在ER模式下使用通用胶粘剂，RL也可能是化学键合的标志。