Effects of two bleaching systems and a whitening mouthwash on the color stability, surface roughness, and microhardness of CAD/CAM materials and a composite resin
Year: 2026
Type: article
Abstract: The preservation of color stability and surface integrity of restorative materials after bleaching remains clinically important. This study evaluated the effects of different bleaching protocols on color change (ΔE₀₀), surface roughness (Ra) and microhardness (VHN) of three CAD/CAM materials IPS e.max CAD (IPS), VITA Suprinity (VS), GC Cerasmart (CS) and one supra-nano-filled composite resin, Estelite Sigma Quick (ESQ), following staining, bleaching, and re-staining procedures. A total of 160 specimens ( n = 40/material; 14.5 × 14.5 × 2 mm) were prepared. After baseline measurements, specimens were immersed in coffee at 37 °C for 14 days. Bleaching protocols included 25% hydrogen peroxide (Philips Zoom), 40% hydrogen peroxide (Opalescence Boost), whitening mouthwash (Colgate Optic White), and distilled water (control). ΔE₀₀ was calculated using the CIEDE2000 formula (α = 0.05), Ra was measured using confocal microscopy and VHN with a Vickers microhardness tester, and Post-bleaching re-staining was performed for 3 days. Normality and homogeneity of variances were assessed using the Kolmogorov–Smirnov and Levene’s tests, respectively. Since parametric assumptions were met, within- and between-group comparisons were performed using repeated-measures analysis of variance (ANOVA) within the general linear model framework. Bonferroni correction was applied for multiple comparisons, and statistical significance was set at p < 0.05. Discoloration followed the order ESQ > CS > VS ≥ IPS. Re-staining was significantly influenced by both material type and bleaching protocol ( p < 0.001). Surface roughness decreased significantly in CS, VS, and IPS ( p < 0.001). After bleaching, Ra increased only in CS treated with 25% hydrogen peroxide ( p = 0.030), whereas treatment with 40% hydrogen peroxide significantly reduced Ra in VS ( p < 0.001) and IPS ( p = 0.001). In contrast, the mouthwash protocol significantly increased Ra in IPS ( p = 0.002). Staining resulted in a significant reduction in microhardness in all CAD/CAM materials ( p ≤ 0.002), while ESQ showed no significant change. Bleaching further reduced the microhardness of both VS and IPS regardless of the bleaching agent used. Bleaching protocols exert material-dependent effects on surface properties and color stability. Resin-containing materials demonstrated greater discoloration, and high-concentration hydrogen peroxide significantly reduced microhardness in glass-ceramic materials. Material composition should be considered when planning bleaching in patients with existing restorations.
Source: BMC Oral Health
Institution: Sağlık Bilimleri Üniversitesi
Language: English
Subfield: Orthodontics
Field: Dentistry
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $3,190
OpenAlex ID: W7204145653
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