Sorption and Color Stability of Bulk-fill and Conventional Composite Resins Immersed in Water and Stained Solutions

Objectives: The objective of this study was to evaluate the sorption (S) and color stability (ΔE) of bulk-fill composite resins and conventional resins after immersion in different solutions.
Methods: Six different composite resins, Filtek Bulk Fill (FTKBC), Aura Bulk Fill (ARBC), Tetric N-Ceram Bulk Fill (TNBC), Filtek Z350 XT (FTKC), Aura (ARC), Tetric N-Ceram (TNC) were evaluated. For each composite resin, 32 disk-shaped (10mm X 2mm) specimens were constructed and randomly distributed into 4 groups (n=8). Specimens were immersed in distilled water, coffee, red wine and Coca-Cola® and data were collected after 10 days (for S) and after 10 and 40 days (for ΔE). Three different measurements were performed for sorption analysis, by weighing the samples according to ISO 4049. A spectrophotometer and the CIE Lab system were used to assess ΔE. One-way ANOVA and the Duncan post hoc test (alpha = 0.05) were used for statistical analysis. Student's t-test was also applied to compare the mean values of ΔE at each time (10 and 40 days).
Results: Significant differences among the materials were found for S and ΔE. The FTKC group produced the highest S values for all the solutions, and presented a similar behavior of the ARC group when immersed in wine and Coca-Cola® (p <0.05). The composite resins showed different levels of ΔE. The values of ΔE increased with the storage time for the groups immersed in the red wine solution, and for the majority of groups immersed in water and Coca-Cola®. Red wine was the most staining solution, followed by coffee, Coca-Cola® and distilled water.
Conclusions: Bulk-fill composites have presented better results for sorption. ΔE values were more influenced by the time and solution than by the type of composite resin.