Development of experimental bleaching agents with bioactive characteristics: analysis of the physical properties of bleached enamel and cell biocompatibility

Abstract

Highly concentrated hydrogen peroxide (PH) 35% are effective in whitening, however, decrease mineral content, change the enamel surface morphology, and promote high cytotoxicity to odontoblastic-like cells. To reverse the mineral loss promoted by PH and decrease the cytotoxicity of bleaching agents, this project aims to develop and analyze bleaching agents containing Biosilicate® (Study 1) or bleaching agents with titanium dioxide nanoparticles co-doped with N and F (N_F_TiO2, Study 2). In Study 1, sound and eroded enamel blocks (early-stage erosion) will be treated with: PH (commercial control), PH 35% associated with different Biosilicate® concentrations (0, 2.5, 5 and 7.5% w/v), gel with Biosilicate® without PH (2.5, 5, 7.5, w/v) and control (without bleaching). In Study 2, sound enamel blocks will be treated with: PH 35% (PH 35% commercial control), PHe 6, 15 and 35% (PH 6, 15 and 35% experimental); PHe 6, 15, 35% with N_F_TiO2 (at 0, 5, 10, 20, 30, 40 or 50% v / v) and control group without treatment. Bleaching will be performed in 3 sessions of 40 min with an interval of 7 d. In both studies, it will be carried out in Phase 1 (n = 12): the mineral content [surface microhardness (KHN), FT-Raman spectroscopy (FT-Raman), polarized light microscopy (MLP), longitudinal section microhardness (MSL), spectroscopy (X-ray dispersive energy, EDS)], roughness [profilometry (Study 1 only), atomic strength (AFM), and morphology (SEM scanning electron microscopy)]; Phase 2 (n = 10): alteration color (spectrophotometer [parameters L *, a *, b *, lightening index (WID) and color change (”E)] and decomposition rate (titration); Phase 3 (n = 10): cytotoxicity (MTT test), cell morphology (SEM) and Phase 4: characterization of experimental gels (pH, preliminary and accelerated stability) and particle characterization in SEM (Study 1) or MET (Study 2). Data will be submitted to statistical analysis and according to normality, the adequate tests will be performed (± = 5%). (AU)