Effect of Enamel Etching Time on Roughness and Bond Strength

Enamel surface conditioning is an important component of adhesive dentistry. Traditionally, phosphoric acid has been used to condition enamel. Newer self-etch adhesives now use acidic monomers for enamel treatment. Objective: The purpose of this study was to examine the effect of different enamel conditioning times on surface roughness and bond strengths. Methods: Surface roughness(Ra) and composite to enamel bond strengths(SB) were determined following treatment of flat ground human enamel (4000 grit) with four adhesive systems: 1)Adper Single Bond Plus(SBP), 2)Adper Prompt L-Pop(PLP), 3)Clearfil S³ Bond(CS3) and 4)Xeno IV(X4) using recommended and extended treatment times (n=10/group). A control group for Ra (4000 grit surface) was also included. The phosphoric acid conditioner of SBP(etch-and-rinse system) was rinsed from the surface with an air-water spray and the other three self-etch adhesive agents were removed with alternating rinses of water and acetone. A Proscan 2000 profilometer was used to determine Ra values. Composite(Z100) to enamel bond strengths (24h) were determined using an Ultradent fixture and debonded with a crosshead speed 1mm/minute. Data were analyzed with ANOVA and Tukey's post hoc test. Results:

Conclusions: Extending enamel treatment time with self-etch systems (PLP-CS3-X4) did not increase surface roughness or bond strength of a resin composite. Increasing the treatment time with phosphoric acid produced greater surface roughness (p<0.05) but did not result in significantly higher bond strength (p>0.05).