The Use of Air-blast to Test the Sealability of Dentine

Objectives: The objective of this study was to use air-blast to test the sealability of dentine by measuring the amounts of fluid loss during stimuli before and after treating with two different adhesive systems in vitro.
Methods: The experiments were carried out on 24 extracted human third molars. After the root was cut, the occlusal dentine was exposed. In group 1 (12 teeth), each specimen was connected to a fluid filtration device to measure the amounts of fluid loss from dentine produced by air-blast for 3 s before and after etch-and-rinse adhesive treatment (Adper^TMSingleBond2). An air-blast was applied onto the exposed dentine from a triple syringe (reservoir pressure = 60 PSI, 25°C, 50%humidity ; distance 5 mm). Then, a fine diamond bur in an airotor was used to remove the adhesive layer and recreated the new smear layer. The amounts of fluid loss from dentine, produced by air-blast, before and after self-etching adhesive (Clearfil^TMLinerBondF) were recorded again. In group 2 (12 teeth), the experiments were performed exactly the same as group 1, except the sequence of self-etching adhesive were done first.
Results: The amounts of fluid loss induced by 3 s air-blast at baseline (dentine with smear layer) for etch-and-rinse group were 0.599±0.614 nL/mm² (N=24) and significantly decreased to 0.174±0.201 nL/mm² after adhesive application (Paired t-test, P<0.001). The corresponding values for self-etching adhesive were 0.611±0.640 nL/mm² and 0.040±0.059 nL/mm² respectively (P<0.001). The amounts of fluid loss caused by air-blast significantly less after treated with self-etching system (P<0.001).
Conclusions: It is concluded that air-blast could be used to test the sealability of dentine by measuring the amounts of fluid loss during the stimuli in vitro. This study indicated that the sealability of dentine treated with self-etching adhesive was significantly better than etch-and-rinse adhesive system.