Abstract

ABSTRACT Objectives To evaluate the color change and trans‐amelodentinal cytotoxicity of a 22% carbamide peroxide (CP) bleaching gel containing different concentration of manganese oxide (MnO 2 ). Material and Methods Enamel/dentin discs adapted to artificial pulp chambers were distributed according to treatments: CN—No treatment; CP22%–22%CP; CP22 + 2MnO 2 –22%CP + 2 mg/mLMnO 2 ; CP22% + 6MnO 2 –22%CP + 6 mg/mLMnO 2 ; CP22% + 10MnO 2 –22%CP + 10 mg/mLMnO 2 applied for 2 h for 15 days. Color change—CC (ΔE 00 and ΔWI D ) ( 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 H 2 O 2 degradation (ANOVA/Sidak), and trans‐amelodentinal diffusion of H 2 O 2 ( n = 8) (ANOVA/Tukey) were also evaluated. Results CP22 + 10MnO 2 presented higher CC than CP22 for both evaluated equations in all analysis periods ( p ≤ 0.04). Among bleached groups, CP22 + 10MnO 2 presented the highest OH • generation ( p ≤ 0.02) and the lowest trans‐amelodentinal diffusion of H 2 O 2 ( p ≤ 0.0004). Therefore, MDPC‐23 cells in CP22 + 10MnO 2 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 MnO 2 to a 22%CP bleaching gel also reduces significantly the trans‐amelodentinal diffusion of H 2 O 2 , diminishing the cytotoxicity caused by at‐home bleaching therapy. Clinical Significance The addition of MnO 2 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.