Color Change and Cytotoxic Effects of a Bleaching Gel With 22% Carbamide Peroxide Catalyzed by Manganese Oxide
Rafael Antonio de Oliveira Ribeiro, Victória Peruchi, Leonardo Novaes Gaeta Sônego, Igor Paulino Mendes Soares, Diana Gabriela Soares, Josimeri Hebling, Carlos Alberto de Souza CostaABSTRACT
Objectives
To evaluate the color change and trans‐amelodentinal cytotoxicity of a 22% carbamide peroxide (CP) bleaching gel containing different concentration of manganese oxide (MnO2).
Material and Methods
Enamel/dentin discs adapted to artificial pulp chambers were distributed according to treatments: CN—No treatment; CP22%–22%CP; CP22 + 2MnO2–22%CP + 2 mg/mLMnO2; CP22% + 6MnO2–22%CP + 6 mg/mLMnO2; CP22% + 10MnO2–22%CP + 10 mg/mLMnO2 applied for 2 h for 15 days. Color change—CC (ΔE00 and ΔWID) (n = 8) was determined at 5, 10, and 15‐day periods (ANOVA/Sidak). Trans‐amelodentinal cytotoxicity (TC) was assessed after applying the extracts to cultured MDPC‐23 cells, which were analyzed concerning their viability (Vi) (n = 8) and oxidative stress (OxS) (n = 8). The amount of hydroxyl radical (OH•) (n = 4) generated by H2O2 degradation (ANOVA/Sidak), and trans‐amelodentinal diffusion of H2O2 (n = 8) (ANOVA/Tukey) were also evaluated.
Results
CP22 + 10MnO2 presented higher CC than CP22 for both evaluated equations in all analysis periods (p ≤ 0.04). Among bleached groups, CP22 + 10MnO2 presented the highest OH• generation (p ≤ 0.02) and the lowest trans‐amelodentinal diffusion of H2O2 (p ≤ 0.0004). Therefore, MDPC‐23 cells in CP22 + 10MnO2 exhibited the lowest OxS (p < 0.0001) and consequently the highest Vi (p ≤ 0.0146).
Conclusion
Besides increasing the bleaching efficacy, the strategy of adding 10 mg/mL of MnO2 to a 22%CP bleaching gel also reduces significantly the trans‐amelodentinal diffusion of H2O2, diminishing the cytotoxicity caused by at‐home bleaching therapy.
Clinical Significance
The addition of MnO2 to a 22% carbamide peroxide bleaching gel improves the color change and reduces the cytotoxicity effects of the product, making at‐home bleaching faster and biologically safer.