Effect of air-blowing time and long-term storage on bond strength of universal adhesives to dentin.

Abstract

To evaluate the effects of air-blowing time and storage time on microtensile bond strength (μTBS) of universal adhesives to dentin. Ninety flat dentin surfaces from extracted human third molars were bonded with three universal adhesives (Clearfil Universal Bond-CU; G-Premio Bond-GP; Scotchbond Universal Adhesives-SB). Bonded dentin surfaces were air-dried for 5s, 15s, or 30s followed by resin composite built-up. Resin-dentin beams were tested with μTBS test after different storage time in distilled water (24h and 1year). Data were analyzed by three-way ANOVA and Duncan test at (α = 0.05). Failure mode and resin-dentin interfaces were observed using a scanning electron microscope (SEM). Specific features of fractured beams after μTBS were further observed using SEM at high magnification. Extension of air-blowing time from 5s to 30s increased the 24h μTBS of CU only. Bond strength of all adhesives significantly decreased after 1-year storage except for CU at 5s and 30s of air-blowing time. One-year μTBS were significantly higher when air-blowing times were extended to 15s for SB and 30s for CU. Air-blowing time had no influence on GP. The effect of air-blowing time and storage time on resin-dentin bond was material-dependent. Extended air-blowing time increased the bond strength and bond durability of CU. Extension of air-blowing time to 15s and 30s improve the long-term bond strength of SB and CU, respectively.