The effect of viscosity and activation mode on biaxial flexure strength and modulus of dual resin cements

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.