Hybridization morphology and dentin bond stability of self-etch primers with different ethanol/water ratios

Abstract

This study evaluated the influence of ethanol/water ratios on the bond strength to dentin of experimental two-step, self-etch adhesive systems. Self-etch primers were prepared with constant 40 mass % of solvents. The ethanol/water ratios tested were 7:1 (P1), 3:1 (P2), and 1:1 (P3); primers with only ethanol (PE) or water (PW) as solvent were also tested. The bond strength to the dentin was investigated through a microtensile bond strength test. Resin-dentin beam-shaped specimens were obtained and tested after 24 h, 6 months, and 1 year of storage in water at 37°C. The hybridization morphology was analyzed using SEM. For bond strength at 24 h, PE = P1, P1 = P2, and P2, P3 and PW > PE. After 6 months, PE = P1 < P2, P3 and PW. After 1 year, no significant differences among the materials were detected. No significant differences among the periods were detected for PE. For P1, 24 h > 6 months = 1 year. For P2, P3 and PW, 24 h = 6 months > 1 year. For PE and P1, adhesive failures were predominant at 24 h, mixed or adhesive failures after 6 months, and premature debonding was predominant after 1 year. For P2, mixed failures were predominant at 24 h and 6 months, and premature debonding after 1 year. For P3 and PW, mixed failures were predominant at all storage periods. The SEM analysis revealed no clear differences in the hybridization patterns yielded by the water-based primers; PE showed formation of irregular resin tags.

Effect of cariogenic challenge on the stability of dentin bonds

“…Previous studies showed that long-term storage in water and other aging conditions may affect the durability of the dentin bonds 13,16,25,29 . The breakdown of the adhesive interfaces was related to loss of stability of the polymer components of the adhesive assembly 4,9,30 .…”

“…The instability of the adhesion of restorative biomaterials to dentin has been demonstrated in vitro 1,13-16,24,25,30 . Degradation is known to possibly occur in the dentin substrate and/or in the polymer component of the restoratives 3,4,13 .…”

“…Degradation is known to possibly occur in the dentin substrate and/or in the polymer component of the restoratives 3,4,13 . Proper hybridization has been considered a key factor for obtaining durable and strong dentin bonds protected from bacteria and hydrolytic action of oral fluids.…”

“…Studies on the longevity of restorative materials bonded to tooth structures usually simulate the clinical aging of the adhesive interfaces using mechanical/thermal cycling 7,15,19,20,24 or static protocols of water storage 1,8,9,13,14,16,20,25,33 . However, studies on the quality and longevity of bonding to dentin should be carried out simulating the actual conditions of the oral environment.…”

Interfacial Adhesion of a Semi-Interpenetrating Polymer Network-Based Fiber-Reinforced Composite with a High and Low-Gradient Poly(methyl methacrylate) Resin Surface

“…However, ethanol is the most commonly used organic hydrophilic solvent that is used either alone or with water as a co-solvent in various commercially available dental adhesives. For a durable bond, it is imperative that the organic solvents of the adhesive primers evaporate from the site of application because the retention of organic solvents may have a deleterious effect on the bonding of the resin-based materials to the substrate [16].…”