Influence of viscosity and polymerization mode on bond strength of dual-curing resin luting agent to dentin

ABSTRACT

Aim: To evaluate the influence of the viscosity and curing mode on the bond strength of two resincements to dentin. Methods: Eight experimental groups were formed (n = 7) according to thedual-cure resin cements (Nexus 2 - Kerr Corp. and Variolink II - Ivoclar Vivadent), curing modes(dual-cure or self-cure) and viscosities (low and high). Resin cements were applied to pre-curedcomposite resin discs (2 mm thick, Sinfony -3M ESPE), which were fixed to bonded dentinsurfaces. The restored teeth were either light-activated (XL3000 - 3M ESPE) or allowed to selfcuring only. After 24 h, the teeth were both mesiodistally and buccolingually sectioned to obtainbonded beam specimens (0.8 mm2 cross-sectional area). Each specimen was tested in microtensilestrength at a crosshead speed of 0.5 mm/min until failure. Results: Data (in MPa) were analyzedstatistically by three-way ANOVA and Tukey’s post-hoc test (pre-set á = 0.05). No significantdifference was observed between resin cements (p=0.26) and viscosities (p=0.13), however, thecuring mode affected the BS within the viscosities (p=0.01). Statistically significant difference wasobserved for low viscosity Nexus 2 23.8(10.6) (dual-cure) and 16.0(5.1) (self-cure); VariolinkII 28.7(8.7) (dual-cure) and 11.9(3.0) (self-cure). Conclusions: Light activation yielded higherbond strength for the low-viscosity versions of the resin cements.