Purpose:This study investigated the influence of sealant application on stain resistance of a nanohybrid resin composite compared to the efficacy of a bonding agent used as a surface sealant on prolonging color stability of the resin composite.Materials and Methods:28 disc-shaped materials were prepared from a nano-hybrid resin composite Filtek Z550 and assigned to four groups: G1K: nonsealed; G2:Adper Single Bond; G3: Fortify ; G4: Biscover LV. After 24 h storage in distilled water at 37˚C, all specimens were subjected to thermocycling and immersed into coffee solution. Color measurements were performed using spectrophotometer (VITA Easyshade; Vident) according to CIEL*a*b* system.Results:Color change values were significantly different among the groups in each evaluation period except for after thermocycling (p<0.05). For 7 days evaluation period, the difference between G3 and G4 group was statistically significant while G4 exhibited statistically significant differences (p<0.05 and p<0.0001 respectively) compared to control (G1) in 14 day whereas no significant difference was found between GI and GII in 28-day evaluation period. However, ΔE values of sealed specimens (GIII, GIV) differed significantly from non-sealed (GI) specimens after 28 days of immersion in coffee solution (p<0.05 and p<0.0001 respectively).Conclusion:It may be concluded that using a bonding agent as a surface sealant does not increase stain resistance of resin composites of the sealants evaluated. Biscover LV showed the highest efficacy to prolong color stability of the resin composite.

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SummaryBackground: The aim of this in vitro study was to evaluate the effect of different kind of beers on the surface roughness of glazed and polished methacrylate-and Silorane-based resin composites after different immersion periods. Methods: Methacrylate-based resin composites (Tetric N-Ceram, Ceram-X) and a Silorane-based resin composite (Filtek Silorane) were tested in the study. A total of 126 specimens (n=42 for each composite) were fabricated using a cylindrical custom metal mould. Surface roughness measurement was performed using a profilometer at baseline and after a 1-week and 1-month immersion in different kind of beers or distilled water. The results were analysed using repeated measure ANOVA and Tukey's HSD test (α=0.05). Results: Repeated measure ANOVA results revealed that immersion period was a significant factor in the surface roughness of the tested specimens (p<0.001). The lowest surface roughness values were obtained with the specimens' polished Optidisc+BisCover LV. Regardless of the polishing systems used, Tetric N-Ceram showed the statistically lowest surface roughness values (p<0.05), whereas Filtek Silorane showed the highest surface roughness (p<0.001). Conclusion:The surface roughness values of the tested resin composites were affected by the polishing procedure used, the exposure time in the solutions and the type of composite resin.

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