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:
Recommended Treatment Time(RT) | Extended Treatment Time(ET) | |||||
Material | Time(s) | Ra(um) | SB(MPa) | Time(s) | Ra(um) | SB(MPa) |
SBP | 15 | 0.352±0.028 a | 40.5±6.1 a | 60 | 0.733±0.122 a* | 44.2±8.2 a |
PLP | 15 | 0.250±0.331 b | 30.7±4.3 b | 60 | 0.298±0.034 b | 32.9±3.6 b |
CS3 | 20 | 0.102±0.014 c | 25.7±2.4 bc | 60 | 0.107±0.018 c | 26.4±3.4 bc |
X4 | 30 | 0.107±0.010 c | 19.0±7.3 c | 60 | 0.110±0.012 c | 23.9±3.5 c |
Control |
| 0.104±0.016 c |
|
|
|
|
Values in same column with same letter are not different (p>0.05). *=significant difference (p<0.05) between RT and ET. | ||||||
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).