Effect of surface preparation using ethyl acetate on the shear bond strength of repair resin to denture base resin.

This study evaluated the effect of using ethyl acetate as a surface preparation agent on the shear bond strength of repair resin to denture base resin. The flat surfaces of a heat-processed denture base resin were prepared with one of the following: (1) without preparation, (2) 60-second application of ethyl acetate, (3) 120-second application of ethyl acetate, (4) 180-second application of ethyl acetate, and (5) 5-second application of dichloromethane. An autopolymerizing repair resin was applied. The specimens were then immersed in 37 degrees C distilled water for 24 hours. The specimens in groups 1, 3, and 5 were thermocycled up to 10,000 times in water between 5 and 55 degrees C with a 1-minute dwell time at each temperature. The shear bond strengths were determined at a crosshead speed of 1.0 mm/min (n = 10). The morphological changes in the repair surfaces after preparation were observed with a scanning electron microscope. The shear bond strengths of groups 3 and 5 were significantly higher than the other groups before thermocycling (p < 0.05). The shear bond strengths of group 3 were significantly lower than those of group 5 after thermocycling (p < 0.05). The scanning electron microscope (SEM) views showed that the dissolution progressed deeper with the preparation duration. The 120-second surface application of ethyl acetate enhanced the shear bond strength between the repair resin and the denture base resin, although the bond durability was inferior to that of the conventional surface preparation.