The effects of a sodium hypochlorite treatment on demineralized root dentin

Abstract

The effects of a 10% NaOCl treatment for 2 min on demineralized human root dentin were investigated by means of: microradiography (MR), scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and secondary ion mass spectroscopy (SIMS). MR measurements revealed that NaOCl caused a tissue contraction not related to water loss but to removal of organic substance(s), resulting in reductions of the lesion depth and mineral loss values by 15% and 42%, respectively. CLSM observations on wet dentin showed that the dentinal tubules underneath the surface are clearly observable and not deformed substantially by the NaOCl, except near the outermost surface. This indicates the importance of wet as well as of dried (high vacuum) observations. SEM micrographs (high vacuum) showed definite changes in the outer dentin surface structure; 85% of the originally open dentinal tubules were closed after NaOCl treatment. No marked changes were observed in the dentin ultrastructure inside lesions, as shown by SEM on fractured surfaces. SIMS data, pertaining to samples in high vacuum, showed a remarkable increase of chlorine (Cl) content in the entire lesion due to the NaOCl, indicating deep penetration of the original OC1 ions. The results suggest that the 2-min treatment of demineralized dentin by NaOCl solutions removes and/or changes part of the dentin matrix in nearly the whole lesion. As a consequence the mineral is somewhat redistributed, the outermost surface of a few mu m is changed, but the main dentin structure and element composition are still intact. These findings indicate that NaOCl treatments are of interest in remineralization and hyper-remineralization studies of dentin.

Increases in Dentin-bond Strength If Doubling Application Time of an Acetone-containing One-step Adhesive

“…18 Treatment of the demineralized collagen matrix with a proteolytic agent, such as sodium hypochlorite (NaOCl), may have an additional beneficial effect to these adhesives, facilitating infiltration 19 of the acidic resin monomers into the dentin substrate. [20][21] Alternative bonding strategies, such as multiple applications 22 or increased substrate contact time of the acidic primers, 23 may also be helpful in achieving a better link between the adhesives and dental substrates.…”

Effect of Various Surface Treatments on the Microleakage and Ultrastructure of Resin-tooth Interface

“…27 Moreover, as water is required to maintain the collagen in its expanded state, in groups with sodium hypochlorite treatment, removal of the collagen fibers with deproteinizing agents would facilitate the access of resin to a substrate that is more permeable and less sensitive to moisture. 28 The results of this in vivo study demonstrated extensive leakage and generalized gap formation in samples restored with the hybrid composite Spectrum TPH and Prime & Bond NT without any surface treatment in both moist and dry conditions. These results are contrary to the previous in vitro study reporting a significant gap-free attachment of Prime & Bond NT to dentin following the manufacturer's instructions.…”

Pronase Digestion of Carious Dentin

“…Previous observations and preliminary studies in our laboratory indicated that NaOCl also has a considerable capacity to disintegrate carious dentin when applied in a large excess [Nordbø et al, 1996]. Calcified dentin, on the other hand, does not seem to be significantly altered by NaOCl [Rosenfeld et al, 1978], al-though this perception has recently been called into question [Barbosa et al, 1994;Inaba et al, 1995]. The commercially available product Carisolv™ (MediTeam AB, Gothenburgh, Sweden) [Ericson et al, 1999], which is based on an NaOCl-containing solution and represents a further development of the former American product Caridex™, has the capacity to soften carious dentin.…”

“…Pronase proved to be more efficient than collagenase and NaOCl at solubilizing carious dentin, although Inaba et al [1995] showed that NaOCl effectively removed organic components from demineralized, noncarious root dentin. A previous investigation in our laboratory also demonstrated that NaOCl and polyacrylic acid in tandem were able to produce apparently clean cavity walls when used following manual excavation of carious dentin [Nordbø et al, 1996].…”