Whitening Toothpastes Do Not Improve Bleaching Outcomes and May Damage Enamel: Study
A new study published in the journal of American Journal of Dentistry found that concurrent use of whitening toothpastes with at-home bleaching does not improve whitening outcomes and may rather adversely affect enamel by increasing surface roughness and decreasing microhardness.
The study evaluated how different types of whitening toothpastes affect enamel when used concurrently with a standard at-home bleaching protocol. Enamel–dentin specimens were divided into 5 groups based on the brushing medium: distilled water (DW) as a control, regular toothpaste (RT), whitening toothpaste with abrasive agents (WT), whitening toothpaste with abrasive and chemical agents (PT), and whitening toothpaste containing abrasive, chemical, and bleaching agents (HP). All samples underwent standardized brushing and bleaching procedures over a 14-day period.
To assess the impact of these products, researchers measured surface microhardness (SMH), surface roughness (Ra), and color change parameters, including ΔL*, Δa*, Δb*, ΔEab, and ΔE00. Statistical analysis was conducted using two-way ANOVA followed by Tukey’s post-hoc test, with significance set at 5%.
The results revealed that the enamel microhardness significantly decreased, while surface roughness increased from the initial to the final evaluation. This indicates that both brushing and bleaching contribute to enamel wear regardless of toothpaste type. However, differences emerged when comparing the toothpastes themselves.
At the final timepoint, the toothpaste containing abrasive, chemical, and bleaching agents (HP) showed the highest surface microhardness, significantly outperforming all other groups. In contrast, the PT group displayed intermediate microhardness values, suggesting partial protection against enamel softening.
Surface roughness data highlighted a more concerning pattern. The whitening toothpaste formulated with abrasive agents alone (WT) resulted in the highest roughness values, indicating greater surface damage. Regular toothpaste (RT), meanwhile, produced the lowest roughness among the toothpaste groups, suggesting it was less aggressive on enamel during bleaching.
Color analysis showed no statistically significant differences among the groups for overall color change, whether measured by the traditional ΔEab or the more perceptually accurate ΔE00. None of the whitening toothpastes enhanced the bleaching effect when compared to brushing with regular toothpaste or even distilled water.
The study summarize microhardness, roughness, and color outcomes across all groups and timepoints, and illuminates that whitening toothpastes may alter enamel structure without delivering additional whitening benefits. Overall, these findings suggest that patients who undergo at-home bleaching should be cautious about using whitening toothpastes simultaneously.
Source:
Barbosa, C. M., Benati, M. R. L., Vieira Junior, W. F., Dotta, T. C., Scatolin, R. S., & Ferraz, L. N. (2025). Effect of whitening toothpaste on enamel properties during bleaching with 10% carbamide peroxide. American Journal of Dentistry, 38(4), 301-307. https://www.unboundmedicine.com/medline/citation/41388948/full_citation
