In recent years, the popularity of over-the-counter whitening mouthwashes has surged due to their ease of use and affordability. These products promise brighter smiles without the need for professional intervention. This study aimed to evaluate the effectiveness of hydrogen peroxide versus charcoal-based whitening mouthwashes on enamel color, surface roughness, and color stability.
Methods
The study utilized 21 permanent central incisor teeth extracted for periodontal reasons. The roots were sectioned, and crowns were mounted in self-cured acrylic resin blocks. Specimens were divided into three groups: Control group (Distilled water), OW group (Peroxide-based mouthwash - Colgate Optic White), and CP group (Charcoal-based mouthwash - Colgate® Plax Charcoal). Each specimen was immersed in 20 ml of its respective mouthwash twice daily for 12 weeks. Color change was assessed using a VITA Easyshade spectrophotometer, while surface roughness (Ra) was measured using a white light interferometer. To test color stability, specimens were stained with black tea solution and measured after 24 hours.Results
Color Change
Both the OW and CP groups showed significant color changes compared to the control group (p < 0.001). The hydrogen peroxide in Colgate Optic White Advanced effectively whitened teeth by breaking down dark-colored chromophores into smaller molecules. Similarly, charcoal in Colgate Plax absorbed dark chromophores, contributing to significant whitening.Surface Roughness
Surface roughness results showed that the control group had the highest mean Ra value, followed by the OW group, with the CP group having the lowest mean Ra value (p < 0.001). The low percentage of hydrogen peroxide (2%) in Colgate Optic White helped maintain lower surface roughness without damaging enamel. Meanwhile, sodium fluoride in Colgate Plax contributed to enamel remineralization, resulting in even lower surface roughness.Color Stability
After staining with black tea for 24 hours, both OW and CP groups demonstrated better resistance to future stains compared to the control group. This can be attributed to ingredients like acrylates/methacryloylethyl phosphate copolymer in Colgate Optic White and tetrapotassium pyrophosphate in Colgate Plax that help prevent stain formation through their white seal technology.Discussion
The findings indicate that both hydrogen peroxide-based and charcoal-based whitening mouthwashes are effective at improving tooth color while maintaining or reducing enamel surface roughness compared to distilled water as a control. Hydrogen peroxide works by diffusing through inter-prismatic spaces in enamel and breaking down chromophores into smaller molecules that are less visible. This aligns with other studies showing similar results with low concentrations of peroxide being effective for tooth whitening. Charcoal’s ability to bind to tooth surfaces and absorb dark chromophores also proved effective for tooth whitening without significantly increasing surface roughness. However, different formulations or application methods might yield varying results as seen in some conflicting studies. The addition of ingredients designed to prevent future stains further enhances these products' appeal by providing long-term benefits beyond immediate whitening effects. This study underscores the efficacy of both hydrogen peroxide- and charcoal-based whitening mouthwashes not only in achieving immediate tooth whitening but also in maintaining enamel integrity and preventing future stains. As patient demand for aesthetic dental solutions grows, these findings offer valuable insights into safe and effective over-the-counter options for maintaining bright smiles. Reference: Sultan, M.S. Effect of hydrogen peroxide versus charcoal-based whitening mouthwashes on color, surface roughness, and color stability of enamel. BMC Oral Health 24, 897 (2024). https://doi.org/10.1186/s12903-024-04631-wLaboratory findings versus clinical recommendations
An in-vitro comparison can identify differences under controlled conditions, but it cannot reproduce saliva, biofilm, dietary staining, brushing, soft-tissue exposure, patient adherence or long-term sensitivity. Product recommendations should consider concentration, contact time, regulatory status, independent evidence and the cause of discoloration.
| Question | Peroxide rinse | Charcoal rinse |
|---|---|---|
| Whitening mechanism | Oxidation of chromogens | Primarily adsorption claims |
| Evidence base | Depends on formulation and concentration | Insufficient evidence for reliable whitening benefit |
| Safety assessment | Sensitivity and tissue exposure | Abrasivity, particles and formulation variability |
| Clinical limit | Cannot correct every intrinsic discoloration | Should not be assumed safer because it is marketed as natural |
For broader product selection, read the toothbrush evidence review. Daily prevention is covered in the oral-hygiene guide. For post-bleaching evidence, continue with fluoride varnish after bleaching.
Frequently asked questions
Does charcoal mouthwash whiten teeth predictably?
Current evidence is insufficient to support reliable whitening benefit with adequate safety.
Can mouthwash replace professional bleaching?
No. Effects and indications differ, and the cause of discoloration should be assessed.
Is peroxide suitable for everyone?
No. Product concentration, oral condition, sensitivity and directions matter; patients should seek professional advice when uncertain.
