Effectiveness of composite cure associated with different curing modes of LED lights

This study compared the effectiveness of cure of two LED (light-emitting diodes) lights (Elipar FreeLight FL], 3M-ESPE; GC e-Light EL], GC) to conventional (Max MX], Dentsply-Caulk control]), high intensity (Elipar TriLight TL], 3M-ESPE) and very high intensity (Astralis 10 AS], Ivoclar Vivadent) halogen lights. The 10 light-curing regimens investigated were: FL1 400 mW/cm2 40 seconds], FL2 0-400 mW/cm2 12 seconds] --> 400 mW/cm2 28 seconds], EL1 750 mW/cm2 10 pulses x 2 seconds], EL2 350 mW/cm2 40 seconds], EL3 600 mW/cm2 20 seconds], EL4 0-600 mW/cm2 20 seconds] --> 600 mW/cm2 20 seconds], TL1 800 mW/cm2 40 seconds], TL2 100-800 mW/cm2 15 seconds] --> 800 mW/cm2 25 seconds], AS1 1200 mW/cm2 10 seconds], MX 400 mW/cm2 40 seconds]. Effectiveness of cure with the different modes was determined by measuring the top and bottom surface hardness (KHN) of 2-mm thick composite (Z100, 3M-ESPE]) specimens using a digital microhardness tester (n=5, load=500 g; dwell time=15 seconds). Results were analyzed using one-way ANOVA/Scheffe's post-hoc test and Independent Samples t-test (p<0.05). At the top surface, the mean KHN observed with LED lights ranged from 55.42 +/- 1.47 to 68.54 +/- 1.46, while that of halogen lights was 62.64 +/- 1.87 to 73.14 +/- 0.97. At the bottom surface, the mean KHN observed with LED and halogen lights ranged from 46.90 +/- 1.73 to 66.46 +/- 1.18 and 62.26 +/- 1.93 to 70.50 +/- 0.87, respectively. Significant differences in top and bottom KHN values were observed between different curing regimens for the same light, and between LED and halogen lights. Although curing with most modes of EL resulted in significantly lower top and bottom KHN values than the control, no significant difference was observed for the different modes of FL. Hence, the effectiveness of composite cure with LED LCUs is product dependent.