The effect of air-blowing duration on three contemporary all-in-one systems

Objective: To evaluate the effects of air-blowing duration on the bonding performance in three contemporary all-in-one systems. Methods: Three all-in-one adhesives were employed: Easy Bond (EB,3M ESPE, USA), BeautiBond (BB, SHOFU Inc, Japan) and G-Bond plus (GBp, GC Corporation, Japan). 63 human third molars without caries were randomly divided into 21 groups of 3 teeth each, and every 7 groups of each system followed as air-blowing for 5s, 10s, 15s, 20s, 25s, 30s and 35s before light-curing. Then, the teeth were built-up with resin composite (Clearfil AP-X). After 24 hour at 37℃ distilled water storage, the bonded specimens were sectioned into 1.0 mm² sticks, which were subjected to the micro-tensile bond strength (µTBS) test at a crosshead speed of 1mm/min. The obtained data were expressed as MPa and statistically analyzed by Dunnett-Test (the air-duration which revealed maximum µTBS was employed as control group). The dentin side of the fractured surfaces was observed by SEM. Results: The results from the µTBS testing for the groups showed that the best bonding performance in EB and BB would be obtained after 15s air-blowing before light-curing, as for GBp, a longer air-blowing time of 25s performed the best. Studies using SEM showed that, fewer bubbles were observed in the specimens of EB comparing with BB and GBp, and there were no significant differences from 5s to 35s of either system. Conclusion: There was the optimal air-blowing duration for each one-in-one system tested in this study, which should be considered in clinical situation. However, as the oral situation may be different from laboratory condition, optimal air-blowing duration in clinical situation should be clarified in future studies.