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Do the microshear test variables affect the bond strength values?

Abstract:

Little is known about the effect of specimen preparation and testing protocols on the micro-shear bond strength (μSBS) results. To evaluate whether variations in polyethylene rod use affect (μSBS)). Human dentin disks were randomly distributed into six groups (n = 5): polyethylene tube (3 levels) and adhesive system (2 levels). In Group 1, polyethylene tubes filled with polymerized composite) were placed on adhesive covered surfaces. Tubes were removed 24 h after water storage, leaving the rods only. In Group 2, the same procedure was performed; however, tubes were kept in place during testing. In Group 3, composite rods without tubes were placed on adhesive covered dentin. In all groups, adhesives were photoactivated after positioning filled tubes/rods on adhesive covered surfaces. Specimens were tested under shear mode and the data subjected to a two-way ANOVA and Tukey's tests. Groups 1 and 2 resulted in statistically similar mean μSBS (P > 0.05); however, a greater number of pretest failures were observed for Group 1. Higher μSBS values were detected for Group 3, irrespective of adhesive system used (P 0.05). Removing the polyethylene tube before composite rod is placed on dentin affects μSBS values. © 2012 Andrea M. Andrade et al.