Abstract Aim: To evaluate the effects of 10% NaOCl gel application on the dentin bond strengths and morphology of resin-dentin interfaces formed by three adhesives. Methods: Two etch-and-rinse adhesives (One-Step Plus, Bisco Inc. and Clearfil Photo Bond, Kuraray Noritake Dental) and one self-etch adhesive (Clearfil SE Bond, Kuraray Noritake Dental) were applied on dentin according to the manufacturers' instructions or after the treatment with 10% NaOCl (ED-Gel, Kuraray Noritake Dental) for 60 s. For interfacial analysis, specimens were subjected to acid-base challenge and observed by SEM to identify the formation of the acid-base resistant zone (ABRZ). For microtensile bond strength, the same groups were investigated and the restored teeth were thermocycled (5,000 cycles) or not before testing. Bond strength data were subjected to two-way ANOVA and Tukey's test (p<0.05). Results: NaOCl application affected the bond strengths for One-Step Plus and Clearfil Photo Bond. Thermocycling reduced the bond strengths for Clearfil Photo Bond and Clearfil SE Bond when used after NaOCl application and One-Step Plus when used as recommended by manufacturer. ABRZ was observed adjacent to the hybrid layer for self-etch primer. The etch-and-rinse systems showed external lesions after acid-base challenge and no ABRZ formation when applied according to manufacturer's instructions. Conclusions: 10% NaOCl changed the morphology of the bonding interfaces and its use with etch-&-rinse adhesives reduced the dentin bond strength. Formation of ABRZ was material-dependent and the interface morphologies were different among the tested materials.

OBJETIVO: O objetivo do estudo é avaliar o efeito do modo de ativação na resistência flexual biaxial (RF) e módulo (MF) em cimentos resinosos duais. METODOLOGIA: Foram formados oito grupos experientais (n=12) de acordo com cimento resinos (Nexus 2/Kerr Corp. and Variolink II/IvoclarVivadent), modo de ativação (dual ou auto-polimerizado) e viscosidade (baixa e alta). Quarenta e oito discos de cada cimento foram fabridados (0,5 mm espessura por 6,0 mm diametro). Metade dos espécimes foram foto-ativados e a outra metade foi deixado para auto-polimerização. Após dez dias, o teste biaxial foi realizado em máquina de ensaio universal (1,27 mm/min, Instron 5844). Os dados foram analisados estatisticamente por ANOVA e teste Tukey (5%). RESULTADOS: A foto-ativação aumentou a RF e RM para os cimentos em ambas as viscosidades em comparação com os grupos auto-polimerizados. A versão alta viscosidade dos cimentos foto-ativados apresentou maior RF que os cimentos em baixa viscosidade. A viscosidade e o tipo de cimento não influenciam o MF. A foto-ativação aumenta os valores de RF e MF para ambos os cimentos e viscosidades. CONCLUSÃO: O uso de diferentes cimentos com diferentes viscosidades pode influenciar o comportamento biomecânico de cimentos resinoso.

PURPOSE: The aim of this study was to evaluate the effects of curing mode and viscosity on the biaxial flexural strength (FS) and modulus (FM) of dual resin cements. METHODS: Eight experimental groups were created (n=12) according to the dual-cured resin cements (Nexus 2/Kerr Corp. and Variolink II/IvoclarVivadent), curing modes (dual or self-cure), and viscosities (low and high). Forty-eight cement discs of each product (0.5 mm thick by 6.0 mm diameter) were fabricated. Half specimens were light - activated for 40 seconds and half were allowed to self-cure. After 10 days, the biaxial flexure test was performed using a universal testing machine (1.27 mm/min, Instron 5844). Data were statistically analyzed by three-way ANOVA and Tukey's test (5%). RESULTS: Light-activation increased FS and FM of resin cements at both viscosities in comparison with self-curing mode. The high viscosity version of light-activated resin cements exhibited higher FS than low viscosity versions. The viscosity of resin and the type of cement did not influence the FM. Light-activation of dual-polymerizing resin cements provided higher FS and FM for both resin cements and viscosities. CONCLUSION: The use of different resin cements with different viscosities may change the biomechanical behavior of these luting materials.