Deproteinizing effects on resin–tooth bond structures

Abstract

This study investigated the effects of NaOCl on resin-tooth bonds to simulate the situations of long-term durability and caries invasion. Resin-tooth bonded specimens were produced with the use of two resin adhesives (Excite and One-Bond). Resin-tooth bonded beams (adhesive area; 0.9 mm 2 ) were serially sectioned and the specimens were immersed in 10% NaOCl medium for 0 (control), 2, 4, and 6 h after being stored in water for 24 h. After immersion, microtensile bond tests were performed. SEM fractography was conducted to calculate each failure mode by image analysis. In addition, the adhesive interface was examined with the use of TEM. In the control specimens, enamel bond strengths had no difference between Excite (45.6 ؎ 15.0) and One-Bond (56.9 ؎ 12.9). On the other hand, dentin bond strengths had significant difference between Excite (80.6 ؎ 21.2) and One-Bond (50.7 ؎ 11.2). The bond strengths decreased with increased storage time for both systems with enamel and dentin bonds. The deteriorated mineralized dentin of beams resulted in bondstrength reduction for resin-enamel bonds. For dentin bonding, the adhesive interface was gradually dissolved from the outer to the center portion of the beam. The depletion of collagen fibrils within the demineralized dentin or hybrid layer deformation was found under SEM and TEM examinations. These morphological changes are responsible for bond strength reduction of resin-dentin bonds.

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

“…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.…”

Effect of EDTA treatment on the hybrid layer durability in total-etch dentin adhesives

“…NaClO induces the degradation of suboptimally protected collagen fibrils caused by incomplete resin infiltration into the demineralized dentin layer. A previous study reported that when a resin-dentin bond was stored in 10% NaClO aqueous solution, degradation of the collagen fibrils within the demineralized dentin or hybrid layer occurred according to scanning electron microscopy (SEM) and transmission electron microscopy (TEM), which caused a decrease in resin-dentin bond strength 11) . This study examined the effect of an EDTA treatment on the hybrid layer after artificial aging with 10% NaClO aqueous solution.…”

Effect of Metalloproteinase Inhibitors on the Microtensile Bond Strength of Composite Resin to Er:YAG Laser-Irradiated Dentin

“…The 10% NaOCl may affect the resin-dentin bond by two different ways: first, degradation of the etched and non-resin-infiltrated layer; and second, by the collagen fibrils that were not properly resin-infiltrated and/or later exposed because of the resin dissolution by 10% NaOCl (23). Therefore, collagen fibrils in the etched dentin and the resin adhesive may have been affected by 10% NaOCl action, leading to a rapid degradation of the resin-dentin layer (15,24). In the current study, the results demonstrated that the MMP inhibitors, 2% CHX and NaF(5000 ppm) were able to prevent chemical degradation of the adhesive interface, confirming the tested hypothesis.…”