Effect of double-application or the application of a hydrophobic layer for improved efficacy of one-step self-etch...

To evaluate the use of two alternative modes of application (double-application and placement of a hydrophobic resin coat) compared with the manufacturers' directions on the microtensile bond strength (microTBS) of one-step, self-etch systems to enamel and dentin.

Resin composite buildups were bonded to the buccal and lingual ground enamel surfaces and occlusal dentin of third molars using the following adhesives: Xeno III (XE), GBond (GB), Adper Prompt L-Pop (AD) and Clearfil SE Bond (CSE) as the control. The adhesive systems were applied: (1) following the manufacturer's directions (MD), (2) with double-application (DA) or with (3) additional placement of a hydrophobic resin layer (HR) after following the manufacturer's directions. After storage in water (24 hours/37 degrees C), the bonded specimens were sectioned into sticks (0.8 mm2) that were tested until failure at a crosshead speed of 0.5 mm/minute. Data from each substrate were subjected to two-way ANOVA and Tukey's test (alpha = 0.05).

The interaction Adhesive vs. Application mode was statistically significant (p < 0.05) for both substrates. In dentin, XE and GB achieved high microTBS in the HR group (p < 0.05). For AD, the highest microTBS were observed in the DA group (p < 0.05). For enamel, similar microTBS was observed for XE and GB among the three modes of application, while the highest pTBS of AD was observed in the HR group.

The effects of using the double-application and placement of a hydrophobic resin coat on microtensile dentin-bond strength values seem to be effective; however, these techniques in enamel were adhesive-dependent.