Objectives: To compare efficacy of QTH and LED polymerization lamps in curing of low-shrinkage epoxy-based and dimethacrylate-based composite materials.
Methods: Seven QTH and LED polymerization lamps with narrow (LED 1) and broad (LED 2) emission spectra were used to polymerize ring epoxy-based Filtek Silorane (3M-ESPE, A3), dimethacrylate-based Charisma (Heraeus-Kulzer, A2) and Tetric EvoCeram (Ivoclar-Vivadent, bleach XL) differing in photoinitiators used. The extent of curing was characterized by a Knoop hardness measured on top and bottom surfaces of a 2 mm layer, 15 minutes after polymerization. Light intensity and emission spectra were measured with Optometer P-9710 and AstraNet spectrophotometer. Statistical analysis was performed using a two-way ANOVA (polymerization lamp, composite material) and t-tests at p=0.05.
Results: In dimethacrylate-based composites the highest hardness values were found after a 20-second light-curing with QTH and LED 2 lamps. The hardness of a Silorane material was significantly higher when cured with LED 2 lamps and prevailed significantly over the hardness of both control materials.
Conclusions: In spite of a limited number of polymerization lamps tested it seemed that epoxy-based composite material polymerizing via ring-opening cationic mechanism can be adequately polymerized with QTH lamps or LED lamps with a broad emission spectrum, which seems to be a promising alternative to the universal QTH lamp types.
Supported by Ministry of Education Youth and Sports Grant No. 237601/2008.
Material | QTH | LED 1 | LED 2 | ||||
Heliolux DLX1 | Megalux FC | DioPower | Translux PB | BluePhase C8 | G-Light | BluePhase G2 | |
Light intensity mW/cm2 | 654 | 1160 | 366 | 739.2 | 960 | 1113 | 1210 |
Charisma | |||||||
Top | 32.1(0.3)a | 34.9(0.4)b | 20.7(0.2)c | 24.5(0.3)d | 26.6(0.4)e | 23.9(0.4)d | 27.9(2.3)f |
Bottom | 26.2(0.3)a | 27.6(0.3)b | 18.7(0.4)c | 23.3(0.3)d | 23.8(0.5)d | 22.9(0.4)d | 28.5(2.4)b |
Tetric EvoCeram | |||||||
Top | 31.9(2.4)a | 40.2(2.9)b | 23.6(1.9)c | 28.7(2.5)d | 23.9(1.2)c | 38.2(5.0)b | 34.6(3.1)b |
Bottom | 24.5(2.0)a | 32.1(2.7)b | 20.2(1.4)c | 27.2(2.3)d | 23.1(1.5)a | 29.5(3.0)b | 29.2(4.2)b |
Filtek Silorane | |||||||
Top | 50.1(0.4)a | 49.2(0.3)a | 41.3(0.2)b | 43.1(0.3)c | 41.5(0.3)b | 54.2(0.3)d | 53.5(4.8)d |
Bottom | 40.1(0.2)a | 42.3(0.2)b | 40.1(0.3)a | 37.5(0.2)c | 37.2(0.3)c | 45.7(0.2)d | 49.3(3.1)e |