Effects of experimental bleaching gels containing co-doped titanium dioxide and niobium pentoxide combined with violet light

Abstract

Objectives To evaluate the bleaching potential of 6% hydrogen peroxide (6% HP) gels containing NF_TiO2 or Nb2O5 irradiated with a violet LED light, and the effects on enamel mineral content and surface morphology. Methods Particles were synthesized, and experimental gels were chemically analyzed by preliminary and accelerated stability tests, pH, and HP decomposition rate. Enamel blocks were treated with 6% HP gels containing (n = 10): 5% NF_ TiO2, 5% Nb2O5, 2.5% NF_ TiO2 + 2.5% Nb2O5 or without particles (6% HP), irradiated or not with LED, and the control was treated with 35% HP. Color (∆E00) and whitening index (∆WID) variations, surface microhardness (SH), average roughness (∆Ra), Ca-P concentration (EDS), and enamel morphology (SEM) were assessed. Bleaching was performed in 3 sessions of 30 minutes and 7-day intervals. Data were submitted to two- (pH, decomposition rate, ∆E00, and ∆WID) or three-way ANOVA and Bonferroni (SH), Kruskal-Wallis (∆Ra), and Dunnet (α = 0.05). Results No changes in the gel’s color, odor, or translucency were observed, pH (6 to 6.5) remained stable over time, and light irradiation boosted the HP decomposition rate. NF_TiO2 and Nb2O5-containing gels displayed higher ΔE00 and ΔWID when light-irradiated (p < 0.05). Nb2O5 and Nb2O5 + TiO2 decreased enamel SH (p < 0.05), but no SH changes were found among the groups (p > 0.05). No differences among groups were noted in ∆Ra, Ca-P content, and enamel morphology after treatments (p > 0.05). Conclusion Experimental light-irradiated 6% HP gels containing NF_TiO2 or Nb2O5 were chemically stable and exhibited bleaching potential comparable with 35% HP. Clinical Relevance Low-concentrated HP experimental gels stand as a possible alternative to in-office bleaching.