Bleaching efficacy of niobium pentoxide-enriched gels formulated with hyaluronic acid

Aim: This study evaluated the stability, color change, and surface morphology of enamel subjected to an experimental bleaching gel containing hyaluronic acid (HA), 6% hydrogen peroxide (HP) combined with Nb2O5 particles, and irradiated with violet LED light. Methods: Enamel blocks were subjected to bleaching (3 sessions of 30 minutes each) with (n = 10/group): HA-based experimental gels containing 6% H2O2 and different concentrations of Nb2O5 (0, 2.5, 5, and 10% by weight). The gels were irradiated with LED or not, and the control group was treated with a commercial gel containing 35% HP. The pH and H2O2 decomposition rate (%) of the gels were determined, while color change (ΔE00) and the whiteness index (ΔWID) were evaluated before (T0) and 14 days after the treatments (T14), and enamel surface morphology was observed at T14 by scanning electron microscopy (SEM). Data were analyzed by two-way ANOVA followed by Tukey’s post hoc test (α = 5%). Results: The pH of the gels ranged from 6.2 to 7.0. No significant differences in H2O2 decomposition were observed between irradiated and non-irradiated conditions within the experimental formulations. LED irradiation significantly increased ΔE00 and ΔWID. Among the experimental gels, the 10% Nb2O5 formulation showed the greatest bleaching response and, under LED irradiation, produced a ΔE00 statistically comparable to that of the 35% HP control. No evident differences in surface morphology were observed among the groups. In conclusion, the gels containing hyaluronic acid and Nb2O5 exhibited stable pH values above 6.2. Violet LED irradiation enhanced the bleaching efficacy of the 6% HP experimental gels, particularly the formulation containing 10% Nb2O5, without evident enamel morphological changes under the conditions evaluated.