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

OBJECTIVES: The objective of the study is to evaluate the bleaching potential of 6% hydrogen peroxide (6% HP) gels containing NF_TiO(2) or Nb(2)O(5) 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. Bovine enamel blocks were treated with 6% HP gels containing (n = 10): 5% NF_TiO(2), 5% Nb(2)O(5), 2.5% NF_TiO(2) + 2.5% Nb(2)O(5) or without particles (6% HP), irradiated or not with LED, and the control was treated with 35% HP. Color (∆E(00)) 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 min and 7-day intervals. Data were submitted to two- (pH, decomposition rate, ∆E(00), and ∆WID) or three-way ANOVA and Bonferroni (SH), Kruskal-Wallis (∆Ra), and Dunnet tests (alpha = 0.05). RESULTS: No changes in the gel's color, odor, or translucency were observed. The pH (6 to 6.5) remained stable over time, and light irradiation boosted the HP decomposition rate. NF_TiO(2) and Nb(2)O(5)-containing gels displayed higher ∆E(00) and DeltaWID when light-irradiated (p < 0.05). Nb(2)O(5) and Nb(2)O(5) + NF_TiO(2) decreased enamel SH (p < 0.05), but no SH changes were found among 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_TiO(2) or Nb(2)O(5) were chemically stable and exhibited bleaching potential comparable with 35% HP. CLINICAL RELEVANCE: Low-concentrated HP gels containing NF_TiO(2) or Nb(2)O(5) and light-irradiated stand as a possible alternative to in-office bleaching.