Effect of light intensity, distance and light curing time on resin-composite to enamel adaptation – analysis by scanning electronic microscopy

Abstract

The aim of this study was to analyze the marginal adaptation in enamel / composite resin interface by scanning electronic microscopy when varying light intensity, distance and light curing time of the material. Twelve teeth were used for preparing forty-eight cavities (2,2 mm diameter x 4 mm deep) in buccal, lingual, mesial and distal surface). The cavities were restored applying a nanofilled resin (SupremeTM, 3M-ESPE) in a single layer, and cured by the following variables: 180 or 580 mW.cm-2, 20 or 40 seconds of irradiation time, 0 mm or 8 mm of distance. The groups were described as: G1 - 20s x 180 mW.cm-2 x 0 mm; G2 - 40s x 180 mW.cm-2 x 0 mm; G3 - 20s x 580 mW.cm-2 x 0 mm; G4 - 40s x 580 mW.cm-2 x 0 mm; G5 - 20s x 180 mW.cm-2 x 8 mm; G6 - 40s x 180 mW.cm-2 x 8 mm; G7 - 20s x 580 mW.cm-2 x 8 mm; G8 - 40s x 580 mW.cm-2 x 8 mm. The restorations were prepared for SEM evaluation intending to analyze enamel / composite resin interface. The results were submitted to Kruskal-Wallis analysis (α = 0,05). Groups 1, 2, 5 and 6 showed better marginal fitting when compared to groups 3, 4 and 7. Group 8 did not show statistical difference. It is possible to conclude that, between groups, the less marginal adaptation was found at the low intensity. Both light curing time and distance did not show influence on marginal adaptation.