Degradation of resin–dentin bonds using NaOCl storage

Effect of Chlorhexidine on Dentin Bond Strength of Two Adhesive Systems after Storage in Different Media

“…An in vivo analysis of bond degradation between adhesive systems and dentin after exposure to NaOCl revealed that the collagen fibrils that are not completely infiltrated by adhesive are deproteinized. A 10% NaOCl solution, which may act as a deproteinizing agent, has been described as a rapid method for simulating the degradation that occurs in vivo (13,14) by the removal of organic components at bonding interfaces (13). The solution acts on the formation of superoxide radicals, inducing the phenomena of oxidation that break up the peptide chain (14).…”

“…Yamauti et al (14) demonstrated that the use of a 10% solution of NaOCl is able to dissolve the hybrid layer of both conventional and self-etching adhesives. These authors showed that there was a reduction in the microtensile bond strength values after a storage period of 5 h. Similar results were obtained by Monticelli et al (23), indicating that this reduction in bond strength was strongly related to the storage period, since storage in a NaOCl solution for 1 h was not sufficient to completely dissolve the hybrid layer.…”

“…These authors showed that there was a reduction in the microtensile bond strength values after a storage period of 5 h. Similar results were obtained by Monticelli et al (23), indicating that this reduction in bond strength was strongly related to the storage period, since storage in a NaOCl solution for 1 h was not sufficient to completely dissolve the hybrid layer. On the other hand, De Munck et al (13) observed a reduction in bond strength to dentin for a one-step HEMA-free adhesive after storage in a 10% NaOCl solution for 1 h. The literature reports that the main effect of bond strength degradation when specimens are immersed in NaOCl occurs during the first hour of storage (14), and sometimes longer storage times may not result in an additional reduction in bond strength (24). It must be emphasized that according to De Munck et al (13) the reduction in bond strength values in microtensile tests after storage in NaOCl was relatively high, particularly when compared with other artificial aging methodologies, such as thermal cycling, for example.…”

“…More aggressive storage media, such as sodium hypochlorite (NaOCl), have been proposed (13,14). Use of NaOCl has been suggested for the removal of exposed collagen fibers after acid etching, as an alternative to diminish collagen degradation and incomplete adhesive infiltration.…”

Degradação de interfaces adesivas formadas após desmineralização e desproteinização da dentina

“…O espaço em torno das fibrilas expostas de colágeno permite a penetração de ácidos, dos metabólitos bacterianos e da água, e pode assim acelerar a degradação da interface adesiva. Yamauti et al (2003) e Yoshida et al (2004) demonstraram uma deterioração na resistência de união para um adesivo convencional simplificado (total-etch) quando as interfaces de união do material com a dentina foram armazenados em solução de hipoclorito de sódio a 10% por 1 a 5 horas. De acordo com os autores, esta deterioração adesiva foi resultado da desproteinização, causada pelo NaOCl, da zona basal da camada híbrida, que é rica em colágeno não encapsulado pelo adesivos.…”