Effect of ultrasonic vibration on dentin bond strength and resin infiltration.

PURPOSE: To apply a vibration technique to compare the bond strength and resin penetration depth into the dentin tubules with those gained using conventional techniques. METHODS: Eighty-eight noncarious extracted human permanent molar teeth were sectioned to remove the coronal enamel. They were embedded in a 1-inch PVC pipe with an acrylic resin. The occlusal surfaces were placed so that the tooth and the embedding medium were at the same level to form a single flat surface. The samples were subsequently polished with silicon carbide abrasive papers, and randomly assigned to four groups (n=22). In Groups 1 and 2, Single Bond was used, and in Groups 3 and 4, One-Step was used. Each adhesive system was applied according to its manufacturer's instructions. For Groups 2 and 4, vibration was applied with an ultrasonic scaler for 10 seconds, and the adhesive was light-cured for 10 seconds. The resin composite was condensed onto the prepared surface in two increments using a Teflon mold and each increment was light-cured for 40 seconds. After 24 hours soaking in tap water at room temperature, the specimens were thermocycled, and the shear bond strengths were measured using a universal testing machine. One-way ANOVA test followed by Student-Newman-Keuls test (P < 0.05) were used to analyze the results. To investigate the infiltration patterns of the adhesive materials, the surface of the specimens was examined with electron microscopy. RESULTS: The shear bond strengths of the vibration groups (Groups 2, 4) were significantly higher than those of the non-vibration groups (Groups 1, 3). The shear bond strengths of Single Bond and One-Step were not significantly different. The vibration groups showed greater numbers of resin tags in the tubules and lateral branches under SEM than the non-vibration groups.