Objectives: The objective of this in vitro study was to compare the Vickers hardness profile of a hybrid composite polymerized with different light curing units. Methods: Split molds 2 mm in depth with a 4 mm diameter were filled with Tetric Ceram (A2), covered with mylar strip, and the composite material was cured using : Astralis 10 (AS=1200 mW/ cm 2, Vivadent, Schaan, Liechtenstein), Swiss Master Light (SW=3000 mW/cm 2, EMS, Nyon, CH), Freelight2 (FL=800 mW/cm 2, 3M-ESPE, St Paul USA). Light exposure times used were 20, 40, 60 s (AS and FL) and 6, 10, 20s (SW). The samples were immediately sectioned, polished and five Vickers hardness measurements (VHN) were obtained at 250, 600, 1000, 1400, 2000 microns below the surface of the composite exposed to the light (0.5 kg load for 15s). Mean hardness values (VH) were obtained from 4 replicates. One-way ANOVA and Tukey HSD tests (a=0.05) were used for statistical analysis. Results: The mean hardness of the composite specimens significantly varied with curing light, duration of exposure and depth. SW light produced top hardness values of 170 compared to 148 for FL and 116 for AS. In comparison, a mean hardness value of 100VH was obtained at 1000 microns below the surface after 10 s of irradiation with SW, 16 s with FL2 and 37s with AS. Conclusion: The LED curing unit (FL) shows significant potential but have lower curing effectiveness than higher powered QTH as the Swiss Master light (SW).

Back to the Dental Materials: VIII - Others-Non-metallic Program
Back to the 81st General Session of the International Association for Dental Research (June 25-28, 2003)

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