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The purpose of study was to compare the plasma arc light with the halogen light in compostte resin curing. Materials and Methods : Three composite resin materials(Z-100, 3M, USA; Tetric Ceram, Vivadent, Liechtenstein; SureFil, Dentsply, USA) were filled in the teflon molds (4mm in diameter and 2, 3, 4, 5 mm in thickness) and cured with either the conventional low-intensity light curing unit with a halogen lamp (Optilux 360, Demetron, USA) for duration of 40 seconds or with the high-intensity light curing unit with a plasma arc lamp (Flipo, Lokki, France) for duration of 3, 6, and 9 seconds. The intensity of halogen light was about 370 mW/cm2 and that. *of plasma light was about 1,900 mW/cm2. After one week, the surface hardnesses of both the top and the bottom of the resin samples were measured with a microhardness tester(MXT70, Matsuzawa, Japan). Results : There were significant differences in the hardness between the top and the bottom of the resin samples except the 2mm thickness samples cured by halogen light for 40s or by plasma light for 9s. There was no significant difference between the hardness values of the top surfaces of the thickness groups. The hardness values of the bottom surfaces decreased as the curing time decreased and as the thickness of resin samples increased, and the three kinds of resin composites showed similar patterns. Conclusion : The results suggest that the halogen light for 40 seconds might be able to cure greater depth of resin composites than the plasma light for 3, 6, or 9 seconds.
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