Effect of Activated Charcoal Mouthwashes and Repolishing on the Color Stability and Surface Roughness of Resin Composites After Long-Term Water Aging

This in vitro study evaluated the effects of activated charcoal mouthwashes on the color stability and surface roughness of resin composites after long-term water aging and repolishing. One nanofilled (Filtek Universal) and two nanohybrid composites (Optishade Universal, Neo Spectra ST HV) were prepared as disks (n = 12/group). After baseline measurements, specimens were aged in water for 6 months (37 °C), immersed in Colgate Plax White+Charcoal, Natural Mouthwash Charcoal, or distilled water for 12 h, and then repolished. Color change was assessed using CIEDE2000 (ΔE00; acceptability threshold = 1.8) and surface roughness (Ra) by profilometry. Data were analyzed using three-way ANOVA (α = 0.05). Six-month aging caused clinically unacceptable discoloration in all materials (ΔE00 = 6.13–8.87). Charcoal mouthwashes produced partial color recovery, greater with Natural Mouthwash (ΔE00 = 2.85–3.20) than Colgate (ΔE00 = 4.20–5.85), though values remained above the clinical acceptability threshold. After repolishing, only Optishade-Colgate reached an acceptable color. Charcoal increased roughness (Ra = 0.168–0.195 µm), but repolishing restored near-baseline values. Overall, repolishing effectively recovered surface smoothness but provided only limited color recovery, with most materials remaining above clinically acceptable thresholds.