Interface analysis of direct restorative systems on human enamel and dentin

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.