Evaluation of micro shear bonding strength of two universal dentin bondings to superficial dentin by self etch and etch-and-rinse strategies

BACKGROUND: Universal bondings can be used either with the etch-and-rinse or self-etch technique. Thus, the present study was done to evaluate the micro-shear bonding strength of two types of Universal Bondings to superficial dentin i.e self-etch and etch and rinse. MATERIAL AND METHODS: The samples included 70 tooth blocks taken from 35 extracted sound premolar teeth. The superficial dentin was exposed to grinding by 800 grit silicon carbide Disk. The samples were randomly divided into 5 equal groups (14 samples in each group). Scotch bond universal (3M/USA) and All bond universal (BISCO/USA) were applied by self-etch and etch and rinse technique in group 1-4 and Adper Single bond 2 (3M/USA) was used in group 5 as etch and rinse for the control group. Z250 XT (3M/USA) resin composite was bonded in tygon tube on surfaces of samples and were cured. Specimens were stored in distilled water at 37ºC for 24 h and then subjected to the micro shear bond strength test in a universal testing machine at a crosshead speed of 0.5 mm/min. The data were analyzed by two-way ANOVA and Tukey test. Failure mode was determined using a stereomicroscope under 20X magnification. Significance level was considered 0/05. RESULTS: The mean of micro-shear bonding strength and Standard Deviation of groups in Mega Pascal are respectively: 35.74 (6.21), 29.50 (3.89), 24.60 (3.53), 31.47 (4.73), 18.09 (3.87). The self-etch technique for Scotch bond Universal and the etch and rinse technique for All bond Universal showed higher micro shear bonding strength. Adper single bond 2 showed the lowest bond strength to a significant level in comparison to other groups (p<0.05). Failure mode was predominantly adhesive. CONCLUSIONS: The micro shear bonding strength of universal adhesives was highly bonding-dependent. Universal bondings had higher micro-shear bonding strength than Adper single bond 2. Key words:Bond strength, dentin, self-etch, etch-and-rinse, universal bonding.