Interface analysis of direct restorative systems on human enamel and dentin

ABSTRACT The present study aimed to characterize the interface between resin and dental substrate submitted to the etch-and-rinse and self-etching restorative process, leading to the presence of gaps and infiltration of adhesive systems in dental substrates. The analysis was done in two dental substrates: enamel and dentin. Six healthy teeth, previously collected and stored were sectioned into three distinct axes to evaluate adherence in relation to dental morphology. A universal adhesive system was applied in etch-and-rinse and self-etch way. The self-etch technique is not effective in enamel, so gaps were produced. But etch-and-rinse is more efficient due to the demineralization process by a strong acid, generating adhesive mechanical imbrications. For dentin, etch-and-rinse formed a thick hybrid layer, irregular and penetration of resin tags; and self-etch formed a thinner hybrid layer, homogeneous and without tags. The size of the hybrid layer and penetration of tags didn’t influence the bond strength, which is dependent on the factor of quality hybrid layer and its interaction with the substrate.摘要 本研究旨在表征经酸蚀-冲洗（etch-and-rinse）与自酸蚀（self-etching）修复工艺处理后，树脂与牙体组织（dental substrate）之间的界面特征，该界面可出现粘接间隙与粘接剂在牙体组织内的渗透现象。本研究选取两种牙体组织作为分析样本：牙釉质（enamel）与牙本质（dentin）。预先收集并保存的6颗健康恒牙，按三个不同轴向进行切片，以评估其与牙体形态相关的粘接性能。采用通用粘接剂分别以酸蚀-冲洗法与自酸蚀法实施粘接操作。自酸蚀技术对牙釉质粘接效果不佳，因此会产生粘接间隙；而酸蚀-冲洗法因通过强酸实现脱矿过程，可形成机械性树脂嵌合结构，粘接效率更优。对于牙本质而言，酸蚀-冲洗法可形成较厚的混合层（hybrid layer），结构不规则且伴随树脂突（resin tags）的渗透；自酸蚀法则形成更薄的混合层，结构均质且无树脂突生成。混合层厚度与树脂突渗透程度均不影响粘接强度（bond strength），粘接强度取决于混合层的质量及其与牙体组织的相互作用。