Effect of six month storage on microtensile bond strength of new elective etching adhesive system on dentin in self-etching or etch-and-rinse approach

Abstract

The aim of this study was to evaluate the microtensile bond strength (μTBS) to dentin of an elective etching adhesive system applied in etch-and-rinse (ER) or self-etching (SE) mode after 6-months of storage in water. Thirty-six caries-free, human third molars were collected and stored in a 0.1% thymol solution. Dentin surfaces were exposed by 600-grit silicon carbide paper and teeth were divided into six groups (n = 6), according to the adhesive systems: a 2-step SE system, Clearfil SE Bond (CSE); a 1-step SE adhesive Adper Prompt L-Pop (LPOP); Scotchbond Universal applied as a 1-step SE adhesive (SBU-SE) and applied as a 2-step ER adhesive (SBU-ER); and two 2-step ER adhesives: Adper Single Bond Plus (SBP) and Optibond Solo Plus (OSP). Composite build-ups were constructed with TPH3 and cured in three increments of 2 mm each. Specimens were sectioned with a slow-speed diamond saw under water in X and Y directions to obtain bonded beams that were tested to failure in tension at a crosshead speed of 1.0 mm/min after one week or 6 months of storage in water. Statistical analyses were computed using Repeated-Measures ANOVA and Fisher's LSD Tests (α = 0.05). There were no significant differences between 1-week and 6-months. SBU-ER and SBUSE showed the highest μTBS values and statistically differed from LPOP (Fisher's LSD). The SBP, OSP, and CSE groups showed intermediary μTBS and did not differ statistically from SBU-ER, SBUSE or LPOP, which presented the lowest μTBS values. The use of elective etching adhesive system in dentin with the etch-and-rinse or self-etching approach did not compromise the bond strength and showed stable bonds after six months of storage in water.