The effect of desensitizers on the bond strength of dentine

Objective: The purpose was to evaluate the bond strength of total-etch/self-etch dentine bonding systems after using 2 desensitizers on exposed dentine and investigate the bond interface by SEM. Material and methods: 30 integrity, non-carious human third molars were used. The occlusal enamel was removed and divided into 3 groups with 10 teeth each. These 3 groups were treated with water(C), UltraEZ¢â (U) and MI Paste (M) respectively. Then each was divided into Single Bond 2(S) and Xeno ¥²(X) adhesive group, which were bonded using the 2 dentine adhesive systems. A block of composite resin was build up to 4-5mm. All the teeth were sectioned occluso-gingivally to obtain bar-shaped specimens with bonded surface area about 0.9 mm •0.9mm. The tension of the sample was tested by a microtensile tester (Bisco, USA) at 1 mm/min. The mean values of bond strength were compared using two-way ANOVA. 3 samples were chosen randomly from each group for SEM investigation. Results: Two-way ANOVA revealed that there were significant (P<0.05) differences within each factor. There were no significant differences between UltraEZ¢â treated group and control group both in Single Bond 2 and in Xeno ¥² groups. There were significant differences between MI treated group and control group in two adhesive groups. The bonding strength of total-etch dentine bonding system was higher than self-etch bonding system. For SEM, the hybrid layer was thin and dense in six groups. Both total-etch and self-etch bonding systems could get fair resin tag infiltration in control and UltraEZ¢â treated group. In MI treated groups, the resin tags were relatively shorter and fewer than the anterior mentioned two groups. Conclusion: The bonding strength of Single Bond 2 was higher than Xeno ¥². UltraEZ¢â had no effect on bond strength of both kinds of dentine bonding systems, while MI paste could diminish it.