Effect of intensity of light sources and barriers in ceramic hardness of dual-cured cement

AbstractIntroductionThe dual-cure resin cement is the main material for luting of ceramic. However, factors such as light source can influence the performance of the cement.ObjectiveEvaluate the influence of two light sources of different intensities on the microhardness of a resin cement when cured under different ceramics.Material and methodForty samples of dual resin cement were photoactivated by two LED light sources, with light intensity of 1000mW/cm² and 800mW/cm², respectively (40 seconds), under the base ceramic Zirconia, Spinel MgAl2O4 and Lithium Disilicate. In the control group, a glass plate was used. Each samples had the surface grounded (600 and 1200). After dry storage in the dark (24 hours), Vickers microhardness measurements were performed (HMV Shimadzu - 50gf/10 seconds). The data were submitted to factorial ANOVA and Tukey's test with significance level of 5%.ResultThe average hardness and standard deviation in the control group for cement polymerized 1000mW/cm² was 43.9±1.5 and 800mW/cm² the value of 43.4±1.3. The lowest value was for the Ceramic base of spinel MgAl2O4, light cured with 800mW/cm² with a value of 34.3±3.3.ConclusionThe ceramic type and intensity of the light source influence the hardness of the cement. The polymerization 1000mW/cm2 on the ceramic based on zirconia and spinel MgAl2O4 resulted in the best combination of hardness cement.