Spectrophotometric Evaluation of Color Changes of Bleach-shade Resin-based Composites after Staining and Bleaching

Abstract

Spectrophotometric evaluation of color changes of Bleachshade resin-based composites after staining and bleaching.Aim: The aim of this study was to evaluate the color stability of two commercially available bleach-shade resin composites (RC) after exposure to 3 storage solutions and the effect of 3 bleaching agents on the color stability and stain removal from stained RC. Materials and methods:Two bleach-shade RC were evaluated in this study, including a nanofilled RC, Filtek TM Z350 XT (FZ), and a nanohybrid RC, Tetric ® N-Ceram (TC), in the extra-white body (shade) (XWB) and L shades, respectively. Twenty-seven disk-shaped specimens, each measuring 12 mm in diameter and 2 mm in thickness, were prepared for each RC, with a total of 54 specimens. Specimens were randomly allocated into 3 groups of 9 specimens each and immersed in 3 storage solutions (distilled water, tea and coffee) for 7 days period. The 9 specimens in each staining group were further divided into 3 subgroups. Specimens in each subgroup (n = 3) were bleached using one of the bleaching agents (10 and 16% Zoom NiteWhite amorphous calcium phosphate (ACP), and Zoom 2 chairside with light activation) for 5 days period. The specimen colors were measured with spectrophotometer. The measurements were performed on each sample three times at baseline, after staining, and after bleaching. Color was expressed using the commission international de I'Eclairage (CIE) L*a*b* color space. The color differences (∆E) between the three measurements were calculated and the results were statistically analyzed using Two-way and Three-way analysis of variance (ANOVA) and Tukey's posthoc tests. Level of significance was set at p < 0.05. Results: Tetric® N-ceram materials demonstrated significantly less color change than the FZ and the color change, which was greater after storage in coffee compared to tea, was statistically significant. The bleaching agents significantly influence the color changes of composite specimens. All groups showed (∆E) values below 3.3 after bleaching, except for 'Zoom 2 chairside' with light activation groups, which is shown clinically unacceptable lighter shade (ΔE >3.3). Conclusion: Bleach-shade composites showed significant discoloration (ΔE > 3.3) after being immersed into coffee and tea solutions. Nanofilled composites discolored more than nanohybrid composites, and carbamide peroxide-based bleaching agents were effective in reducing the discoloration to a clinically acceptable value (∆E > 3.3). ORIGINAL RESEARCHClinical significance: In this study, after clinically significant discoloration, low concentrations of carbamide peroxide bleaching agents were effective in removing stains and restoring the color of bleach-shade composites to near baseline color.

Effects of adhesive used as modeling liquid on the stability of the color and opacity of composites

“…Therefore, several studies have evaluated the color stability of composites subjected to staining solutions. In the most of these studies, the specimens have been immersed in coffee, grape juice, wine, and other beverages uninterruptedly for long periods of time (hours or days) . However, the exposure of composite restorations to beverages in vivo occurs through several cycles of a few seconds each.…”

“…However, similar indexes between the bleached cylinders and those observed at baseline were reached only for specimens modeled with the Adper Universal. Prior studies have demonstrated the ability of bleaching agents to reduce the color and opacity of composite specimens stained by extrinsic pigment molecules . Similar to dental bleaching performed in a tooth's hard tissues, the bleaching effect is likely to be associated with pigment molecule degradation .…”

“…Another important point is that the beneficial effects of the modeler liquid include reduction of defects present in the composite restoration . Most of the laboratorial studies evaluating color stability have examined composite specimens immersed in staining solutions over a particular period of time . Despite the fact that this protocol does yield color changing in specimens, the use of a constant temperature does not reproduce the dimensional alterations the material undergoes when patients drink hot or cold beverages .…”

“…Thermal cycles yield volumetric changes that can enhance possible defects in the composite specimens with possible higher penetration of the staining solution into the porous material. Regarding the propensity to staining, the color of resin‐based materials can also be modified by bleaching agents, while the ultimate composite color can be improved so that it does not present a perceptible difference from that observed prior to staining …”

Influence of Bleaching Agents on Color and Translucency of Aged Resin Composites

“…Dental bleaching procedures, both at‐home and in‐office, are effective practices to remove intrinsic and extrinsic discoloration from the dental hard tissues . The potential effect of bleaching agents on resin composites seems to depend on type and concentration of bleaching agent, as well as on the restorative material tested . Nonetheless, the literature is not conclusive about the action of different (in‐office and at‐home) bleaching agents in different resin composite opacities .…”