Methods: Twenty specimens were obtained (2mm high and 4mm in diameter) from each resin cement: RelyX®Unicem (3M ESPE AG - Seefeld, Germany), Multilink®Automix (Ivoclar-Vivadent – Schaan, Liechtenstein) and AllCem® (FGM - Joinville – SC, Brasil). Ten specimens were then light-cured using a halogen curing-light according to manufacturer’s instructions; the other ten samples were sealed with a black opaque adhesive tape, ensuring a light-proof polymerization. Both groups were placed in an incubator at 37ºC for 24 hours. After this period the samples were submitted to Vickers microhardness test with 5 indentations per specimen. Inferential statistics analysis was performed at a 5% significance level. Student´s t-test was used for curing procedures’ comparison and one-way ANOVA was applied to compare the three cements in each curing procedure.
Results: RelyX®Unicem (p=0,221) and AllCem® (p=0,984) showed similar microhardness between the light-cured and the self-cured samples. Multilink®Automix was the only one to show higher values in the light-cured group (p=0,000). RelyX®Unicem had the higher microhardness values (light-cured p=0,001;self-cured p=0,000) , followed by AllCem® and Multilink®Automix.
Conclusion: Results suggest that RelyX®Unicem and AllCem® don’t benefit from light- activation in terms of conversion rate. However, Multilink®Automix was influenced by light in its conversion rate.