Effects of Charcoal-Based Mouthwashes on Color Change and Surface Roughness of a Stained Resin Composite

Charcoal-based mouthwashes have recently gained popularity, but current evidence on their effects on the color change (ΔE00) and surface properties of resin composites is limited. This study aimed to evaluate the effects of five charcoal-based mouthwashes on the color change and surface roughness (Ra) of a stained resin composite.

Seventy disc-shaped resin composite specimens (Filtek Z250) were prepared and immersed in coffee for 12 days. The specimens were then randomly distributed into seven groups (n = 10), based on mouthwash used: five charcoal-based mouthwashes (Hello Activated Charcoal Extra Freshening Mouthwash, My Magic Mud Activated Charcoal Alcohol-Free Oral Rinse, Dr. Jones' Naturals Activated Charcoal Mouthwash, The Humble Co. Natural Mouthwash Charcoal, and Colgate Plax White + Charcoal), one hydrogen peroxide-based mouthwash (Crest 3D White), and artificial saliva. Each specimen was immersed in the relevant mouthwash for 60 seconds, rinsed with water for 30 seconds, and then immersed again in a fresh mouthwash solution for 60 seconds to simulate daily mouthwash use. This cycle was repeated to represent 1, 2, 3, 4, and 12 weeks of use. Color measurements were performed at baseline, after staining, and after 1, 2, 3, 4, and 12 weeks. Surface roughness was evaluated after staining and after 1, 2, 3, 4, and 12 weeks of immersion. The surface morphology of the specimens was examined using a scanning electron microscope. The data were analyzed using repeated measures ANOVA and Tukey's test (α = 0.05).

After immersion in coffee, the resin composite exhibited discoloration above the 50:50% acceptability threshold (AT) (ΔE00: 1.8). After 12 weeks of use, only one charcoal-based mouthwash, Colgate Plax White + Charcoal, and Crest 3D White reduced the ΔE00 of the resin composite below the AT, but both showed a significant increase in Ra (p < 0.001) and caused changes in surface morphology of the resin composite. The other charcoal-based mouthwashes did not cause an increase in Ra (p > 0.05) but failed to reduce the ΔE00 of the material below this threshold.

All charcoal-based mouthwashes, except Colgate Plax White + Charcoal, maintained surface integrity but failed to reduce the color change below the AT. The hydrogen peroxide-based mouthwash provided color improvement on the resin composite but led to increased surface roughness.