Microtensile dentin bond strength and interface morphology of different self-etching adhesives and universal adhesives applied in self-etching mode

Abstract

To evaluate the microtensile dentin bond strength (BS) and dentin-adhesive morphology of three self-etching bonding systems and three universal adhesives applied in self-etching mode. Four single-step adhesives: G-Premio BOND (GPB), Bond Force II (BOF), Prime&Bond Active (PBA), and Adhese Universal (ADU); and two two-steps adhesives: Clearfil SE Bond (CSB) and Clearfil SE Bond 2 (CS2) were tested. Dentin surfaces of extracted third molars were prepared for microtensile bond strength test using adhesives applied according to the manufacturers’ instructions and restored with resin composite. Restored teeth (n = 8) were sectioned to obtain beam samples that were tested after 24 h and 1 year of water storage. Data were analyzed by two-way ANOVA repeated measures and Tukey's test (α = 0.05). The micromorphology of dentin-adhesive interfaces (n = 3) was analyzed by scanning electron microscopy (SEM) at 2.000× magnification. Self-etching adhesives exhibited different bond strength values at 24 h evaluation, which ranged from 20.7 to 77.9 MPa. PBA, ADU, CSB, and CS2 showed significantly higher dentin bond strength than GPB and BOF. These two single-step adhesives presented the lowest dentin bond strengths for both storage times, and interfacial study by SEM analysis revealed short and few resin tags formations. Water-storage for 1 year did not reduce the dentin bond strength of all adhesives tested. All self-etching and universal adhesives tested presented stable bond strength over one year of water storage. Both two-step self-etching adhesives yielded immediate and long-term higher dentin bond strength than most single-step adhesives tested.