Manganese oxide increases bleaching efficacy and reduces the cytotoxicity of a 10% hydrogen peroxide bleaching gel.

OBJECTIVE

The study aims to assess the effects of a 10% HO bleaching gel with different MnO concentrations on the bleaching efficacy (BE), degradation kinetics (DK) of HO, and trans-amelodentinal cytotoxicity (TC).

MATERIALS AND METHODS

Standardized bovine enamel/dentin disks (n = 96) were placed in artificial pulp chambers, and the bleaching gels were applied for 45 min. Thus, the following groups were established: (G1) no treatment (negative control/NC); (G2) 35% HO (positive control/PC); (G3) 10% HO; (G4) 10% HO + 2 mg/mL MnO; (G5) 10% HO + 6 mg/mL MnO; and (G6) 10% HO + 10 mg/mL MnO. After analyzing bleaching efficacy (ΔE and ΔWI), the degradation kinetics of HO and trans-amelodentinal cytotoxicity were determined (n = 8, ANOVA/Tukey; p < 0.05).

RESULTS

G6 presented BE (ΔE and ΔWI) statistically similar to G2, which represented conventional in-office bleaching (p = 0.6795; p > 0.9999). A significant reduction in the diffusion of HO occurred in G3, G4, G5, and G6 compared to G2 (p < 0.0001). The highest DK of HO occurred in G6 (p < 0.0001), which had the lowest TC in comparison with all other bleached groups (p ≤ 0.0186).

CONCLUSION

The addition of 10 mg/mL of MnO in a 10% HO bleaching gel potentiates the degradation of this reactive molecule, which increases the BE of the product and decreases TC.

CLINICAL SIGNIFICANCE

Replacing a 35% HO gel commonly used for conventional in-office dental bleaching by a 10% HO gel containing 10 mg/mL of MnO reduces the cytotoxicity of this professional therapy, maintaining its excellent esthetic efficacy.