Objective: This study aimed to assess the bond strength and marginal microleakage in composite resin restorations, using the Single Bond Universal adhesive system associated with Ultralux (halogen) and Bluephase (LED) light curing units. Methods: For bond strength, 80 healthy human third molars were divided into halogen light (n=40) and LED (n=40), and subdivided according to the following application techniques for the adhesive system: etch-and-rinse (enamel), self-etching (enamel), etch-and-rinse (dentin), and self-etching (dentin). The teeth were subjected to the microtensile test and the fracture pattern was observed under an optical microscope at 40X magnification; they were analyzed by ANOVA, and Fisher and Tukey’s tests (5%). For the marginal microleakage test, 120 class II cavities were prepared in 60 healthy human third molars that were randomly divided into halogen light (n=30) and LED (n=30), and subdivided according to the following application techniques for the adhesive system: etch-and-rinse, selective etching, and self-etching. The teeth were thermocycled 2000 times (±5/55°C), stained in 5% basic fuchsin and sectioned for qualitative and quantitative assessments; they were analyzed by Kruskall-Wallis and Dunn tests (5%). Results: For the bond strength of enamel and dentin, the adhesive application with prior acid etching was better than self-etching (p<0.0001), regardless of the type of light curing unit (p<0.05). Etch-and-rinse showed the lowest microleakage values (p<0.0001). Conclusion: Etch-and-rinse obtained the best results relative to the other application techniques for the adhesive system in both tests, regardless of the type of light curing unit.

Objective The evolution of adhesive dentistry and the addition of nanoparticles has heralded an improvement in the mechanical properties of adhesives. Thus, the aim of the present study was to evaluate the effects produced by carbon nanotubes (CN) added to two adhesives used for indirect bonding by an examination of the shear bond strength (SBS) and location of bond failure. Methods One hundred and sixty bovine incisors were randomly divided into eight groups (N = 20): (1) indirect bonding with Sondhi adhesive; (2), (3) and (4) indirect bonding with Sondhi adhesive into which CN at 0.5%, 0.25% and 0.05% concentrations were incorporated; (5) indirect bonding with Concise adhesive; (6), (7) and (8) indirect bonding with Concise adhesive into which CN at 0.5%, 0.25% and 0.05% concentrations were incorporated. Following etching with 37% phosphoric acid and the placement of brackets, maximum shear bond strength (SBS) was measured with a mechanical testing machine. The location of bond failure was evaluated using the Adhesive Remnant Index (ARI). The SBS between groups and ARI scores were statistically analysed (p < 0.05). Results There was no statistical difference (p > 0.05) in SBS or ARI. Conclusions CN addition to Concise and Sondhi adhesives did not influence the SBS and the ARI of the brackets. Therefore, in the conditions of this experiment, there was no benefit in the addition of CN to orthodontic adhesives.

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