| Background The wet-bonding technique is recommended for one-bottle dentin adhesive systems. However, the moisture concept varies widely among the instructions of manufacturers as well as among investigators. The aim of this study was to evaluate the effects of different dentin surface moisture on the microtensile bond strengths of an ethanol/water-based and an acetone-based adhesive systems to dentin. Methods 40 intact human premolars extracted for orthodontic reasons were used. Superficial occlusal flat dentin of these premolars were exposed, finished with wet 600-grit silicon carbide paper. Under four wet and dry conditions (overwet, blot dry, one-second dry and desiccated), resin composite was bonded to dentin using Single Bond or Prime & Bond NT according to the manufacturers' instruction. The teeth were longitudinally sectioned in the "x" and "y" directions to obtain bonded sticks with a cross-sectional area of 0.81mm2 with a slow-speed diamond saw. The specimens were tested in tension at 1mm/min until rupture of the bond and the fracture modes were observed with stereomicroscope. The mean bond strengths were analyzed by one-way ANOVA and paired t-test. Results The bond strength of overwet/Single Bond, blot dry/Single Bond, one-second dry/Single Bond and desiccated/Single Bond groups were 10.87 MPa, 22.47 MPa, 24.91 MPa and 12.99 MPa, respectively. The bond strength of overwet/ Prime & Bond NT, blot dry/ Prime & Bond NT, one-second dry/ Prime & Bond NT and desiccated/ Prime & Bond NT groups were 10.02 MPa, 20.67 MPa, 21.82 MPa and 10.09 MPa, respectively. For both Single Bond and Prime & Bond NT, the blot dry group and one-second dry group revealed significantly higher bond strengths than the overwet and desiccated groups (p<0.05). Conclusions In order to achieve the highest bond strength to dentin, keeping the dentin surface an appropriate moisture condition is critical for the one-bottle dentin adhesive systems with ethanol/water or acetone solvent. |
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