Effectiveness of immediate bonding of etch-and-rinse adhesives to simplified ethanol-saturated dentin

Abstract

This study examined the immediate bond strength of etchand-rinse adhesives to demineralized dentin saturated with either water or absolute ethanol. The research hypothesis was that there would be no difference in bond strength to dentin between water or ethanol wetbonding techniques. The medium dentin of 20 third molars was exposed (n = 5). The dentin surface was then acid-etched, left moist and randomly assigned to be saturated via either water wet-bonding (WBT) or absolute ethanol wet-bonding (EBT). The specimens were then treated with one of the following etch-and-rinse adhesive systems: a 3-step, water-based system (Adper Scotchbond Multipurpose, or SBMP) or a 2-step, ethanol / water-based system (Adper Single Bond 2, or SB). Resin composite build-ups were then incrementally constructed. After water storage for 24 h at 37°C, the tensile strength of the specimens was tested in a universal testing machine (0.5 mm/min). Data were analyzed by two-way ANOVA and Tukey's test (α = 5%). The failure modes were verified using a stereomicroscope (40×). For both adhesives, no significant difference in bond strength was observed between WBT and EBT (p > 0.05). The highest bond strength was observed for SB, regardless of the bonding technique (p < 0.05). No significant interaction between adhesives and bonding techniques was noticed (p = 0.597). There was a predominance of adhesive failures for all tested groups. The EBT and WBT displayed similar immediate bond strength means for both adhesives. The SB adhesive exhibited higher means for all conditions tested. Further investigations are needed to evaluate long-term bonding to dentin mediated by commercial etch-and-rinse adhesives using the EBT approach.

One-Year Evaluation of a Simplified Ethanol-Wet Bonding Technique: A Randomized Clinical Trial

“…This characteristic allows for water sorption and adhesive interface hydrolysis, which causes a significant decrease in adhesion over time (1,3,18). From a laboratory point of view, the EWBT seems to overcome part of this problem (6,8,20).…”

“…The spaces among the collagen fibrils increase, which makes hydrophobic monomer infiltration easier, reducing hydrophilicity of the interface (6,18,20).…”

“…In the most commonly used technique, the dentin is first saturated with 50% ethanol, followed by 70, 80, 95 and 100% solutions (4,8,9). Gradual ethanol saturation seems to be a necessary step to prevent collagen from collapsing and to replace the total amount of water within the demineralized dentin (3,6,8). However, this laboratory procedure takes a long time, which turns the technique clinically unsuitable (8).…”

“…Presence of hydrophilic monomers and incomplete resin infiltration in demineralized dentin by etch-and-rinse technique may increase water sorption and risk of hydrolytic degradation, which may reduce the adhesive mechanical properties over time (1,(6)(7)(8)(9).…”

“…Dentin dehydration occurs with application of increasing concentrations of ethanol solutions, allowing the subsequent infiltration of a hydrophobic primer followed by a hydrophobic adhesive resin (3,6). This hybrid layer is less hydrophilic and more resistant to overtime hydrolytic degradation caused by the endogenous enzymes, such as metalloproteinases (MMPs), due to a more effective collagen protection (19,20) and prevention of phase separation (8,18,21,22).…”