Analysis of the bleaching potential and effects on dental structures of experimental bleaching agents containing TiO2 nanoparticles co-doped with fluoride and nitrogen

Abstract

The aim of this study is to evaluate the bleaching and mineral recovery potential, enamel morphology and biocompatibility of experimental in-office bleaching gels (6%, 15% e 35% H2O2, HP) containing different concentrations of titanium dioxide (TiO2) nanoparticles co-doped with fluoride (F) and nitrogen (N) [N_F_TiO2, 5-50% (v/v), in increments of 5%]. Bovine enamel blocks (5x5x3mm) will be submitted to staining and initial colorimetric and surface microhardness (KHN) evaluation (T0). Afterwards, the specimens will be randomly treated with HP (6, 15 or 35) with N_F_TiO2 under concentrations of 5, 10, 20, 30, 40 ou 50%. Groups with HP without NF_TiO2 and without treatmens will be adopted. Three 40-min bleaching sessions (T1 - T3) with blue LED irradiation will be performed during 40 min/each at 7-day intervals with storage in remineralizing solution among sessions). At T3, peroxide decomposition and pH analyses will be executed by means of titration with potassium permanganate and a microelectrodom, respectively. Mineral content will be analysed under cross-sectional microhardness/polarized light microscopy (after 14 days of storage in remineralizing solution - T14), FT-Raman spectrocopy/Energy-dispersive x-ray dispersive (EDX) (T0 and T4). Surface roughness and morfology of enamel will be analysed under atomic force microscopy and surface electron microscopy, respectively (T0 and T14). Cytotoxic of the experimental bleaching gels will be determined by means of MTT assay and cell morphology evaluation under SEM. Data will be submitted to exploratory statistical analysis, and the adequate test will be performed for each analysis under 5% significance level. (AU)