Method:Three self-adhesive resin cements; Clearfil SA Luting (Kuraray Medical), RelyX Unicem 2 (3M ESPE) and BeautiCem SA (Shofu) were used. Ultrasonic measurements were carried out using a pulser–receiver, transducers and an oscilloscope. The resin cements were mixed, inserted into a transparent mould, and then placed onto a sample stage. Power densities of 0 (no light irradiation), and 600 mW/cm2 were used for curing, and temperatures were set at 23°C and 37°C. The transit time through the resin cement was divided by the specimen thickness to obtain the longitudinal sound velocity (V). The mean and standard deviation for each resin cement were subjected to a one-way analysis of variance (ANOVA) and Tukey’s Honestly Significant Difference (HSD) test at a significance level of 0.05.
Result:The rate of V increase was slower when the self-adhesive resin cements were not light-irradiated, and became faster when irradiated. The rate of sound velocity increase had a tendency to retard when the cements were storage at lower temperature.
Conclusion:The polymerization behaviour of the self-adhesive resin cements was affected by the power density of the curing unit and the ambient temperature. Light irradiation with a sufficient power density is necessary to achieve optimal mechanical properties, even in materials with a dual-cured setting reaction.