Effect of different polishing systems and staining solution on surface roughness and color stability of bulk fill...

To evaluate the effect of polishing systems (discs or rubbers) on surface roughness (Ra) and color change (ΔE) of two bulk fill and one conventional resin composite after immersion in a dye solution.

180 samples (10 mm x 2 mm) were separated into three groups: (1) Resin composite: Filtek One Bulk Fill (FO), Tetric N-Ceram Bulk Fill (TNC), Filtek Z350 XT (FXT) (n= 60); (2) polishing system: unpolished (control); aluminum oxide discs (Sof-Lex, AOD); cup-shaped abrasive rubber polishers (Astropol, CSA) (n= 20), and (3) immersion solutions: coffee or distilled water (n= 10). Immersion was under 5 mL of each solution for 3 hours daily, for 30 days. Measurement of Ra and ∆E was made considering two times: initial (after polishing) and final (after immersion), in addition to surface analysis by scanning electron microscopy at the end. Kruskal-Wallis, Mann-Whitney, and Dunn (α= 0.05) was used.

For the unpolished samples after immersion in coffee, TNC (P= 0.007) showed lower ΔE than FXT and FO. For polished samples with CSA and immersed in coffee, TNC followed by FXT showed lower ΔE than in the absence of polishing. Polishing with AOD and immersed in coffee: FO had smaller ΔE than when not polished. For Ra, TNC and FO had lower values after using AOD, whereas for FXT lower Ra was noted with CSA.

The roughness and color stability of resin composites are mediated by the polished material, polishing system and dye solution. The best results were found for Tetric N-Ceram polished with aluminum oxide discs.