Resin bond strength with different methods to remove excess water from the dentin.

PURPOSE: To compare the resin bond strength using different methods to remove the excess water from the dentin while maintaining it moist. MATERIALS AND METHODS: 60 human molars were randomly divided into four treatment groups of 15 teeth each as follows: Group 1: A wet bonding technique was used as recommended by the manufacturer and was used as a control group. The exposed occlusal dentin surfaces were conditioned with 32% phosphoric acid (Uni-Etch) for 15 seconds and rinsed for 15 seconds. 40 microL of distilled water was added to standardize the content of the water on dentin surface. The conditioned dentin surfaces were gently blow-dried for 3 seconds with oil-free compressed air. The tip of the syringe was placed at 2 cm from the dentin surface. One coat of the One-Step primer/adhesive was applied to the dentin surface using a fully saturated brush tip, allowed to remain on the surface undisturbed for 3 seconds, and then gently air-dried for 3 seconds from a distance of 1 cm to remove excess solvent and water. A second coat of the primer/adhesive was applied and gently air-dried from a distance of 1 cm. The primer/adhesive was light-cured for 10 seconds. Resin composite (Z100, shade A3) was then polymerized for 40 seconds. Group 2: The dentin surface was blot-dried by applying tissue paper (Kimwipes EX-L) adjacent to the exposed area; Group 3: The excess water on the dentin surface was removed using an applicator brush (Bend-a-Brush) for 5 seconds; Group 4: A small dry hydrophilic cotton pellet was gently applied over the dentin surface to remove the excess water. The sequential steps for these three groups were similar to those of Group 1. The dentin surface remained visibly moist in all procedures. After light-curing, the specimens were thermocycled (5 degrees and 55 degrees C, 500 cycles, 30-second dwell time). The specimens were sheared and the data were analyzed using ANOVA and Tukey's test methods. The site of failure was analyzed using a stereomicroscope and a scanning electron microscope. RESULTS: ANOVA revealed that there was a statistically significant difference between the groups (P < 0.05). Turkey's test revealed that Group 1 was significantly lower than Groups 2, 3 and 4 with no difference between the last three groups (P < 0.05). All samples showed resin cohesive failures.