Titanium dioxide nanoparticles co-doped with nitrogenium and fluorine (NF_TiO2) present bioactive features, which can facilitate the decomposition of 35% hydrogen peroxide (HP) in reactive oxygen species (ROS). Therefore, experimental bleaching gels containing NF_TiO2 could become viable alternatives to enhance and to reverse adverse effects of tooth bleaching to the dental structure. Thus, this study will determine the ideal NF_TiO2 concentration to increase the bleaching effectiveness of 35%HP, as well as to overcome the undesirable effects of bleaching to enamel mineral content and surface morphology. Enamel-dentin blocks obtained from bovine incisors will be randomly distributed into groups, according to the treatments (n=10): 1) no bleaching (Control); 2) HP (0%NF_TiO2); 3) HPT15 (HP+15%NF_TiO2); 4) HPT25(HP+25%NF_TiO2); 5) HPT35 (HP+35%NF_TiO2); 6) HPT45 (HP+45%NF_TiO2) and 7) HPT65 (HP+65%NF_TiO2). The colorimetric evaluation (L*, a* e b*) and color change (Cielab -DEab e Ciede 2000- DE00) will be performed by means of a digital spectrophotometer, after specimen preparation (T0), after artificial staining protocol with black tea (T1), after bleaching protocols (T2) and 14 days elapsed from the end of treatment and storage in artificial saliva (T3). Bleaching gels' pH will be measured during bleaching application at 0, 10, 20, 30 and 45 min. The enamel mineral content will be determined using ¼Raman spectroscopy (CO32- e PO43-) and Dispersive Energy Scetropscopy (EDS - Ca and P). The enamel topography will be evaluated by means of Scanning Electron Microscopy (SEM). The obtained data will be submitted to normality assessed and tested with the appropriate statistical analysis.
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