Curing efficiency of LED LCUs for dental composite resin

Objectives: To compare the curing efficacy of two kinds of LCUs curing composite resin. Methods: Ultralume5 and Optilux 501 LCUs were used in this study. Samples of 1mm, 1.5mm, 2.0mm and 2.5mm in depth were made with the two kinds of composite resin, and cured with the two kinds of LCUs for 20s, 40s and 60s respectively. The KHN values on the top and bottom surface were measured with Tukon300 micro-hardness tester. Silicon gel pipes of 8mm in length and 4mm in diameter were filled with the two kinds of composites. And then the depth of cure was measured after curing with two kinds of LCUs respectively for 40s. Results: The multifactor ANOVA showed that the factors of curing time, composite and LCU had a statistically significant influence on the KHN values on the bottom surface of two dental composites. Factor time had the greatest influence (F-ratio=784.4), followed by the composite (F-ratio=265.3) and LCU (F-ratio=22.1), as indicated by the F-ratios. Conclusions: Generally, there was no statistically significant difference in the KHN values on the top and bottom of composites cured with the two kinds of LCUs. Ultralume5 LCUs achieved a greater depth of cure than Optilux501 for composite Ultradent, while there was no difference for composite Chrisma of the two LCUs. The present study shows that LED LCUs have a potential to replace halogen LCUs.