Post-Bleaching and Aging Effects on Composite Resins: a Color Analysis

Objectives: The aim of this study is to evaluate the effect of polishing following bleaching treatment and subsequent aging in distilled water on the color stability of colored composite-resins.
Methods: Discs (10mm*2mm) were fabricated from Clearfil-Majesty-ES-2 (CME), Palfique-Estelite-Paste (PEP), Filtek-Z250 (Z250), Parafil (PF), and Ruby-Comp-Nano (RC) composites (n=20). Samples underwent initial color measurements (control), followed by immersion in coffee for 7 days. 40% Hydrogen Peroxide gel (Opalescence Boost PF) was applied for bleaching. Half of the samples in each group (n=10) were polished with Kerr-Identoflex after bleaching. The samples were then immersed in coffee again for 7 days and subsequently aged in distilled water for 6 mounths. After bleaching, the color change of the polished group is shown as ΔE₀₀₁ and the color change after aging is shown as ΔE₀₀₂; while the color change of the group without polishing is shown as ΔE₀₀₃ and the color change after aging is shown as ΔE₀₀₄. Data were analyzed using one-way ANOVA and Tukey tests (p=0.05).
Results: After bleaching, polished PF and Z250 samples demonstrated significantly more discoloration compared to PEP and RC. However, no significant differences in color change were observed among non-polished samples in the composite resin groups. Following aging in distilled water, no additional significant color changes were detected compared to the measurements taken after coffee immersion.
Conclusions: Polishing after whitening had no effect on color change either before or after aging. However, color change varied depending on the content of the composite-resins.