Active application of primer acid on acid‐treated enamel: Influence on the bond effectiveness of self‐etch adhesives systems

Aim: Evaluate the composite‐to‐enamel bond after passive or active application of self‐etching primer systems on polished or pre‐etched enamel with phosphoric acid. Materials and Methods: Two self‐etch adhesives systems (SEAS) were used: Clearfil SE Bond and Easy Bond. Third human molars were divided into 8 groups (N = 10). The crown of each tooth was sectioned into halves and the mesial/distal surfaces were used. The adhesives were actively or passively applied on enamel with or without prior phosphoric‐acid etching. Resin composite cylinders were built after adhesive application. After stored in relative humidity for 24 hr/37°C the specimens were subjected to microshear test in universal testing a machine at a crosshead speed of 0.5 mm/minute. The results were analyzed with three‐way ANOVA and the Tukey test. The enamel‐etching pattern was evaluated under SEM. Results: The 2‐step SEAS system presented significantly higher adhesive bond strength means (47.37 MPa) than the 1‐step (36.87 MPa). A poor enamel‐ etching pattern was observed in active mode showing irregular and short resin tags, however there was not compromised the bond strength. Conclusion: Active or passive application produced similar values of bond strength to enamel regardless of enamel pretreatment and type of SEAS. It is still no consensus on the techniques that improve adhesion of self‐etch adhesives to enamel. The images produced by SEM showed that the etching pattern of enamel obtained after active or passive application did not influence the bond strength.