The purpose of this study was to evaluate the effect of light curing methods on the marginal sealing and cavity wall adaptation of resin composite restorations, and on the hardness at the top and bottom surfaces of a body of resin composite. Cylindrical cavities, 1 mm deep and 3 mm in diameter (C-factor=2.3) were prepared on flat bovine dentin surfaces. The teeth were restored with UniFil Bond adhesive system followed by UniFil S composite. The resins were cured with NEW LIGHT VL-II (VL-II) and Co-bee (CB) curing lights; Group 1: VL-II 700 mW/cm
2 for 60 5, Group 2: CB 730 mW/cm
2 for 60 5, Group 3: CB 210 mW/cm
2 ramped to 700 mW/cm
2 over 5 s + 700 mW/cm
2 for 55 s. After thermocycling, dye penetration tests around the cavity margin and cavity wall adaptation on cut surface were carried out. Dye penetration length was calculated as a percentage of the total cavity wall length. Composite specimens of 2 mm and 3 mm thickness were polymerized in Teflon molds with three curing lights, and then the top and bottom surfaces hardness were measured using Knoop hardness tester. The ramped curing significantly improved marginal sealing of resin composite restorations. This curing method caused accelelrating the hardening at the bottom surfaces of the resin composite.
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