Air-drying Time of Self-etching Adhesives vs Bonding Efficacy

Purpose: This study tested the effect of different drying times on the efficacy of bond for five self-etching adhesives. Materials and Methods: Four marketed and one experimental adhesive were tested in combination with a hybrid-type resin composite (Venus, Heraeus Kulzer): Clearfil Protect Bond (CPB, Kuraray), G-Bond (GBO, GC), Hybrid Bond (HYB, Sun Medical), iBond NG experimental (ING, Heraeus Kulzer), Clearfil S3 Bond (TSB, Kuraray). Three hundred twenty human molars were randomly divided into 40 separate groups. For shear bond strength (SBS) testing, the adhesives were applied to flat peripheral dentin surfaces. Following the manufacturers' specified dwell times, the adhesives were air dried for 0, 5, 10, or 20 s prior to light activation and seating of composite cylinders (n = 8). The specimens were stored for 24 h in 37°C water and submitted to shear bond strength testing at 1 mm/min. For evaluation of marginal adaptation, Venus restorations were bonded in standardized cylindrical dentin cavities (>4 mm in diameter, 1.5 mm in depth) according to the procedure above and immersed in water at 23°C for 10 min prior to removal of excess using #4000 SiC paper and determination of the maximum marginal gap widths (MGW, n = 8). Bond strength data were analyzed by one-way ANOVA and Duncan's ranking (p 0.05), and marginal adaptation by Kruskal-Wallis ANOVA and Mann-Whitney ranking (p 0.05). Results: Both SBSs and numbers of gap-free restorations increased significantly with drying time (p 0.05). All materials performed best after air drying for 10 s or longer. Conclusions: Since the optimal drying times found diverge from the manufacturer's directions for use, recommendations might need to be revised.