Effect of Activated Charcoal Mouthwashes and Repolishing on the Color Stability and Surface Roughness of Resin Composites After Long-Term Water Aging
Applied Sciences (Switzerland). 2026;16(3):1638.
ABSTRACT
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.
KEYWORDS
activated charcoal · mouthwash · resin composite · color stability · surface roughness · repolishing
STUDY SUMMARY
This in vitro study examined whether activated charcoal mouthwashes and subsequent repolishing could recover the color and surface smoothness of three resin composites after six months of water aging. Aging produced color change well above the clinical acceptability threshold in all materials; the charcoal mouthwashes gave only partial color recovery and increased surface roughness, while repolishing returned roughness close to baseline values. Under the conditions tested, only one material and mouthwash combination reached an acceptable color after repolishing.