Effect of tooth-whitening strips and films on changes in color and surface roughness of resin composites

Though the effectiveness of film and strip type tooth-whitening agents on the bleaching of tooth has been confirmed, there have been few studies on their influence on restorative materials. The purpose was to investigate the effect of tooth-whitening film and strip on the changes in color and surface roughness of dental resin composites. The composites used were Filtek Supreme (3M ESPE), Point 4 (Kerr), and Spectrum TPH (Dentsply). Specimens were prepared 10 mm in diameter and 1 mm in thickness. Film type (Night Effect, Crest; Simply White Night, Colgate) and strip type (Whitestrips Professional, Crest; Claren, LG) agents were used, and bleaching procedures were performed for 2 weeks according to the manufacturers' recommendations. Color was measured according to the CIELab color scale with a spectrophotometer. Color difference ( DeltaE(*)(ab)) and surface roughness ( Ra) were measured. After bleaching, the DeltaE(*)(ab) values were 0.90-1.67, which was too small to be perceptible (<3.3). The increase in Ra values was significant in some composite-whitening agent combinations ( P<0.01), however the value was less than 0.30 microm after bleaching. Therefore the change in surface roughness was clinically insignificant. We conclude that the influence of tooth-whitening film and strip on the color and surface roughness of dental resin composites was negligible.