Introduction

Whitening toothpastes, such as hydrogen peroxide and activated charcoal, are popular alternatives to professional bleaching due to their affordability. However, their effects on enamel integrity remain controversial, as hydrogen peroxide is known for its oxidative bleaching properties. The aim of this study was to compare the effects of whitening toothpastes containing 2% hydrogen peroxide and activated charcoal on enamel color change and surface microhardness.

Material and methods

Sixty sound human premolars were prepared into enamel slabs and randomly allotted to three groups (n = 20): group HP (2% hydrogen peroxide), group AC (activated charcoal), and group C (non- whitening fluoride control). A toothpaste slurry (1 : 3 ratio of toothpaste to distilled water by weight) was prepared freshly before each brushing session. Color change (ΔE) was assessed at baseline and after brushing regi­men using a spectrophotometer device (VITA Easyshade spectrophotometer) according to CIE L*a*b* color system, and surface microhardness was evaluated with Knoop microhardness testing.

Results

All groups exhibited a statistically significant improvement in enamel ΔE. Group HP demonstrated the highest ΔE values, significantly outperforming both group AC and group C. However, hydrogen peroxide toothpaste also led to a significant reduction in enamel microhardness, while group AC and group C exhibited no significant changes in microhardness.

Conclusions

Hydrogen peroxide toothpaste is more effective for achieving noticeable whitening but it has an adverse effect on enamel microhardness. Conversely, charcoal-based toothpaste offers a safer profile concerning enamel microhardness but with reduced whitening efficacy.