Abstract
This study evaluated the surface roughness and color alteration of an aged nanofilled composite exposed to different staining solutions and bleaching agents. Ninety nanofilled composite (Filtek Z350XT, 3M/Oral Care) specimens were submitted to 5,000 thermal cycles and immersed in (n = 30): red wine, coffee, and artificial saliva at 37°C for 48 h. Groups were subdivided according to the bleaching protocol (n = 10) with 20% carbamide peroxide, 38% hydrogen peroxide, or without bleaching - control. Mean surface roughness values (Ra - μm) and color parameters (L*, a*, b*) were measured at baseline (T0), after thermal cycling aging and staining (TS), and after bleaching (TB). Color (ΔE00) and whiteness index (ΔWID) changes were determined after aging and staining (Ts-T0) and after bleaching (TB-TS). The adopted perceptibility and acceptability thresholds of the nanofilled composite were 0.81 and 1.71 ΔE00 units and 0.61 and 2.90 ΔWID units, respectively. Ra was analyzed using mixed models for repeated measurements and L* by the Tukey-Kramer test. The a* and b* values were evaluated by generalized linear models for repeated measures. ΔE00 was tested using two-way ANOVA and Tukey tests, and ΔWID by Kruskal-Wallis and Dunn tests (α = 5%). Ra of all groups decreased after aging and staining (TS, p < 0.05), but increased after bleaching only for groups stained with red wine (TB). Aging and staining decreased the luminosity of the composites, but L* increased after bleaching (p < 0.05). Aging and staining increased a* and b* values, but after bleaching, b* values decreased (p < 0.05). After bleaching, ΔE00 and ΔWID were greater in stained groups at both time intervals, regardless of the bleaching protocol. Stained resin composites exhibited perceptible but unacceptable color (ΔE00 > 1.71) and whiteness (ΔWID > 2.90) changes, regardless of the bleaching treatment performed. Therefore, red wine affected the surface roughness of the aged nanofilled resin submitted to bleaching. Bleaching was unable to reverse the color changes promoted by red wine and coffee on the aged nanofilled composite.
Highlights
Staining beverages and food, pH alterations, temperature oscillations, and the dynamic intra-oral environment incite a challenging condition that can lead to aging and degradation of the composite resin [1, 2]
Bleaching with 20% carbamide peroxide (CP) or 38% hydrogen peroxide (HP) significantly increased the roughness of the composites that were aged and stained with red wine (RW) (p < 0.05) but did not change the roughness of the composite previously aged and stained with CF or immersed in artificial saliva (AS) (p > 0.05)
RW and CF stained composites exhibited lower luminosity values compared to the composite that remained immersed in AS, TABLE 2 | Means and standard deviations of surface roughness (Ra, μm) and color parameters (L*, a*, b*) of the nanofilled composite at baseline (T0), after thermal cycling and staining (TS) and after bleaching (TB)
Summary
PH alterations, temperature oscillations, and the dynamic intra-oral environment incite a challenging condition that can lead to aging and degradation of the composite resin [1, 2]. Tea, red wine, orange juice, some types of soda, and food colorings can change tooth or polymerbased restorations color, especially when frequently ingested [10, 11]. Among these staining agents, red wine is reported to be the most potential color modifying solution [12], due to the concentration of the flavonoids, its low pH, and the presence of alcohol [13,14,15]. The increase in the composite surface roughness raises the possibility of biofilm formation and, the risk of recurrent caries development [20, 21]
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