Investigation of the effects of different bleaching agents and different polishing systems on the surface roughness and color change of nanofil composite resin

The aim of this study was to evaluate the effects of office-type bleaching agents on surface roughness and color change after the composite surfaces unpolished and polished systems are colored in tea and coffee solution. A total of 108 specimens of 8 mm diameter and 2 mm height were prepared of the Filtek Ultimate (3M ESPE, St. Paul, MN, USA) composite resin. 3 main groups were created and one of the groups was left unpolished, the others were polished with Sof-Lex (3M ESPE) discs or OneGloss (Shofu, Kyoto, Japan) rubbers. Then all groups were immersed in tea or coffee solution for one week. After the discoloration process, Opalescence Boost (Ultradent, Utah, USA) or Opalescence Quick (Ultradent) office-type bleaching agents were applied for a total of 2 sessions, one week interval (n=9). Arithmetic surface roughness (Ra) values were calculated using the profilometer after polishing and after bleaching. The color changes of the samples were measured three times using a spectrophotometer: after polishing, after discoloration, after bleaching. The difference between two shades was calculated using the ΔE formula. The statistical analyses were performed by Mann-Whitney U, Kruskal Wallis, Benferonni-Dunn, Wilcoxon Signed Ranks test (p<0,05). In terms of surface roughness values, the highest initial roughness value was observed on polished surfaces with OneGloss (p<0,01). After bleaching, roughness values significantly increased in all groups compared to baseline (p<0,01). In terms of color change, the highest ΔE values were observed on the surfaces colored with coffee (p<0,01). After bleaching, Opalescence Boost was able to reduce the ΔE value below <2,7 in both solutions only on Sof-Lex group.