Effects of artificial staining on bulk-filled resin composites

To evaluate the color stability of bulk-fill resin composites (RC) in comparison to conventional RC submitted to artificial staining.

15 specimens of each RC were prepared. Five bulk-fill RC [X-tra Base (XB), Filtek Bulk-Fill Flowable (FBF), Admira Fusion X-tra (AD), Tetric N-Ceram Bulk-Fill (TB), and Filtek Bulk-Fill (FB) ], and two conventional RC [GrandioSO (GO) and Filtek Z350XT (FXT) ] were used. After preparation of the samples, the specimens were immersed in a staining broth for 5 weeks and repolished. The color change was assessed using a spectrophotometer. Data were analyzed using one-way ANOVA, Tukey's tests, and paired t-test.

The bulk-fill flowable (XB and FBF) presented color change clinically acceptable (ΔE< 2.7) after staining. Among the bulk-fill regular resins, only AD presented clinically acceptable values (ΔE= 1.99). Regarding the conventional resins, GO presented a significantly lower color change than the other resins, but was not significantly different from AD. For all the resins, except AD, the repolishing procedures resulted in a significant decrease of color change. Tested resins did not present the same behavior under staining, despite their similarities. All the resins stained above the perceptibility threshold (ΔE> 1.2). After repolishing, the color change was reduced overall.

Color stability of resin composites was related to the properties of the resin material. The staining degree was related to the replacement of the restorations and repolishing contributes to the maintenance and longevity of these composites.