Hyaluronic Acid-Based Bleaching Gels With NF_TiO2 and Violet LED: Efficacy and Cytotoxicity of Low-Concentration H2O2 for In-Office Bleaching.

Objective: To evaluate the efficacy and cytotoxicity of in-office bleaching gels with hyaluronic acid (HA) or carbomer 940 (CAR), titanium dioxide nanoparticles co-doped with nitrogen and fluorine (NF_TiO₂), and hydrogen peroxide (HP; H₂O₂) at 1.5% and 6% with violet LED irradiation.

Materials and methods: 48 bovine enamel/dentin discs (5 × 3 mm) stained with black tea for 24 h were assigned to six groups (n = 8): HA-1.5%HP + LED, HA-6%HP + LED, CAR-1.5%HP + LED, CAR-6%HP + LED, 35%HP-commercial (control), and a negative control (no treatment). The discs were placed in artificial pulp chambers (APCs) and underwent three 30-min bleaching sessions with 20 violet LED cycles (1-min activation, 30-s pause) at 7-day intervals. Extracts were applied to MDPC-23 cells, assessing color change (ΔE₀₀), whiteness index (ΔWI_D), H₂O₂ diffusion, cell viability (CV), oxidative stress (OxS), and cell morphology (SEM). Data were analyzed by one-way ANOVA and Tukey post hoc test (α = 0.05).

Results: Gels with HA showed no statistical difference in ΔE₀₀ and ΔWI_D compared with 35%HP-commercial (p > 0.05). H₂O₂ diffusion and oxidative stress were lower in 1.5% and 6% HP groups. Cell viability was higher in 1.5% HP groups (p < 0.05). There were no changes in cell morphology.

Conclusion: Bleaching gels with HA, NF_TiO₂ NPs, low H₂O₂ concentrations, and violet LED irradiation reduced cytotoxicity without compromising efficacy.

Clinical relevance: Experimental bleaching gels with hyaluronic acid, NF_TiO₂ nanoparticles, low H₂O₂ concentrations, and combined with violet LED irradiation achieve similar efficacy to high-H₂O₂ gels (35%). This approach also promises to reduce cytotoxic damage, providing a safer in-office bleaching option.