Effect of filler and application mode on micro-shear bond strength of etch-and-rinse adhesive systems

Objective: To evaluate the effect of the application modes and the presence of filler of etch and-rinse adhesive systems on the micro-shear bond strength test (mu SBS) to bovine dentin. Methods: Twenty bovine teeth had the enamel removed and dentin surface exposed. Dentin was etched with 37% phosphoric acid and the following adhesive systems were applied: One Step and One Step Plus with two modes (no rubbing action and vigorous rubbing action). To each tooth six Tygon cylinders with internal 0.76 mm were filled with flowable composite resin. All cylinders were light polymerized for 40 s (Optilux 501). The irSBS was performed in a universal testing machine (Instron 5565), with specimens held in place by a wire (0.2 mm) loop, and force loaded to failure. The fracture mode was evaluated. The results in MPa were statistically analyzed by two-way ANOVA and Holm-Sidak tests (alpha = 0.05). Results: The two-way ANOVA detected no interactions between factors (p = 0.865), but only differences between the adhesive systems (p = 0.042) and application modes (p = 0.014). One Step Plus obtained a higher irSBS than One Step, and vigorous application increased bond strength of adhesives systems. The predominant failure modes of all groups were adhesive mixed. Conclusion: The adhesive systems showed the best irSBS results with presence of filler and active mode application. (C) 2015 Sociedade Portuguesa de Estomatologia e Medicina Dentaria. Published by Elsevier Espana, S.L.U.