To evaluate the effect of air-drying pressure and distance on the micro-shear bond strength (µSBS) of two one-step self-etching adhesives to dentin.
Methods:
A total of 100 bovine anterior teeth were used in this study. The teeth were equally divided into 20 groups (n=5 each) according the type of the self-etching adhesive used (G-Bond, GC Europe N.V., Leuvan, Belgium and Easy Bond, 3M ESPE, St Paul, USA), air-drying pressure (1bar and 4bar) and air-drying distance (1cm, 3cm, 5cm, 7cm and 10cm). The self-etching adhesives were applied according to their manufacturer instructions, in respect to application, evaporation and curing times. The cervical third of each tooth was ground to expose a flat dentin surface, so that two resin composite cylinders, 0.8mm x 0.5mm, were constructed in each tooth. µSBS was performed at a crosshead speed of 0.5 mm/min. Fractured pattern was evaluated using a Scanning Electron Microscope. Three-Way ANOVA was run to evaluate the effect of adhesive, air-drying pressure, air-drying distance and their interactions on the µSBS to bovine dentin.
Results:
Three-Way ANOVA revealed that both adhesive and air-drying distance had a significant effect on the µSBS to dentin (p=0.000 and p=0.047 respectively). On the other hand, the air-drying pressure had no significant effect on the µSBS (p=0.464). The interaction between the three independent variables (adhesive, air-drying pressure and distance) had a significant effect on the µSBS to dentin (p=0.000). Adhesive failure was the predominate failure type.
Conclusions:
Both tested adhesives proved to be technique sensitive regarding the combined effect of air-drying pressure and distance.