Color stability of a bis-acryl composite resin subjected to polishing, thermocycling, intercalated baths, and immersion in different beverages

Objective: To evaluate the color of a bis-acryl resin after polishing, aging, and colorants.

Materials and methods: From the 140 disks obtained, 35 were not polished (NP), 35 were polished with 3-μm (3P), 35 with 3- and 1-μm (1P), and 35 with 3-, 1-, and 0.5-μm sized particles (05P). Five disks of each group were thermocycled for 20, 100, and 200 cycles. Sixty disks were thermocycled and kept in beverages (tea, wine, and coffee) after four cycles. Sixty disks were immersed in the beverages for 24 hours, a week, and a month. The coordinates L*a*b* were measured and the color differences were analyzed by ANOVA. The lightness, chroma, and hue differences were evaluated by repeated measures ANOVA. Comparisons were made with Tukey's test (α = 0.05).

Results: Similar behaviors were observed between 3P and 05P groups (1.53 and 1.95ΔE₀₀ ) (P < .05). The NP group submitted to 200 cycles showed the biggest color differences (3.02) (P = .003). The greatest color differences were observed in the NP group submitted to immersion in coffee (8.30) and wine (7.93) (P < .05).

Conclusions: The polished surfaces were the least stained. Coffee and wine provided the greatest color changes, both for baths and immersions.

Clinical significance: Polishing of provisional surfaces restorations made of bis-acrylic resin is essential to minimize staining caused by aging and use of colorants, regardless of the particle size present in the polishing paste. The contact with coffee and red wine should be avoided, especially for clinical times greater than 1 week.