Objectives:
To evaluate the effect of curing lights and curing duration on depth of cure and elastic modulus of “Bulk-Fill”composites.
Methods:
Cylindrical resin specimens (4mm diam. X 8 mm) were fabricated from: A. Tetric EvoCeram (Ivoclar Vivadent); B. Surefil SDR (Dentsply); and C. Venus Bulk Fill (Heraeus Dental). The Fusion 3 (Dentlight) (LED 1) and Bluphase 16i (Ivoclar Vivadent)(LED 2) photocuring units were used for 10, 20 and 40 seconds. Curing level was assessed through microhardness testing (Vickers, 100g, 25s) at top and bottom, and curing ratio (%) was calculated. For elastic modulus bars (4mm X 25mm X 2mm) were fabricated and tested in flexural mode (Instron). Results were analyzed by ANOVA.
Results:
Curing percentage at 6mm vs. top
Duration | 10s | 20s | 40s |
Composite A LED 1 LED 2 | 75% 83% | 79% 89% | 86% 94% |
Composite B LED 1 LED 2 | 48% 79% | 69% 87% | 79% 95% |
Composite C LED 1 LED 2 | 96% 113% | 112% 113% | 128% 114% |
Mean and S.D of elastic modulus (MPa) vs. curing time
Duration | 10s | 20s | 40s |
Composite A LED 1 LED 2 | 7172±779 7324±520 | 7673±1021 7565±879 | 7652±841 7946±867 |
Composite B LED 1 | 4927±192 4578±218 | 5130±231 4940±169 | 5426±430 5098±364 |
Composite C LED 1 LED 2 | 3143±204 2980±202 | 3104±175 3392±151 | 3232±211 3649±180 |
Conclusions:
Photocuring duration, curing light, and material have significant effect on depth of cure. At 6mm depth with LED 2 the composites achieved a 79%-114% level of curing vs. top, confirming deep curing properties, but not with the LED 1. Photocuring for 40s had a significant effect on producing a higher modulus vs. 10s and composite A had a significant higher elastic modulus than B and C under all curing conditions (p=0.05).