Aim: Considering the recent introduction of universal adhesives and the controversy regarding the use/no use of etchant prior to their application, this study sought to assess the microtensile bond strength of composite to enamel using universal adhesive with/without acid etching compared to three-step etch and rinse, two-step etch and rinse and two-step self-etch bonding agents.
Methods: This in vitro, an experimental study was conducted on 80 extracted sound human molars in five groups (16 each): Scotchbond Universal adhesive (3M) with/without prior etching, Adper Scthe otchbond Multi-Purpose, Single Bond and Clearfil SE Bond. Etching was performed with 37% phosphoric acid for 20 seconds followed by rinsing and drying. The bonding agent was then applied and light-cured. The e-lite composite was bonded to surfaces and light-cured. The teeth were then mounted, sectioned and subjected to microtensile bond strength test in a universal testing machine. The mode of failure was, determined under a stereomicroscope. Data were analysed using one-way ANOVA followed by Tukey's test.
Results: Universal adhesive with prior etching yielded the highest bond strength (P = 0.03). Pairwise comparisons showed that the bond strength of this group was significantly higher than that of universal adhesive without prior etching (P = 0.04). No other significant differences were noted (P > 0.05). The modes of failure were significantly different among the groups (P = 0.003).
Conclusion: Enamel etching with phosphoric acid can significantly increase the bond strength to universal adhesive. Universal adhesive without prior etching provided the bond strength as high as that provided by etching and rinse and self-etch bonding agents.
Keywords: Acid Etching; Composite Resins; Dental; Dental Adhesives; Tensile Strength.