The incorporation of nanoparticles into bleaching gels has been explored as a promising strategy to enhance bleaching efficacy while simultaneously preserving enamel integrity. However, the physicochemical behavior of these formulations and their effects on dental tissues remain insufficiently understood. In this context, this study investigated experimental bleaching gels containing hyaluronic acid (HA) as a thickener, combined with NFTiO2 nanoparticles (NPs) and hydrogen peroxide (HP), irradiated with violet LED. The NPs were synthesized and characterized by X-ray diffraction, FT-Raman spectroscopy, and transmission electron microscopy. The gels were evaluated for pH (0, 15, and 30 min) and peroxide decomposition rate (0 and 30 min). Enamel–dentin discs were randomly allocated to experimental groups (n = 10), varying HP concentration (6 or 35%), NP content (0 or 5%), and LED irradiation, in addition to a commercial control group (35% HP). Bleaching efficacy was assessed by color change (ΔE00) and bleaching index (ΔWID), while enamel effects were evaluated by Knoop microhardness, surface roughness, and scanning electron microscopy after three bleaching sessions and 14 days of storage in artificial saliva. Structural analyses confirmed that the NPs exhibited spherical morphology and an anatase crystalline phase. The experimental gels demonstrated adequate chemical stability, compatible pH behavior, and increased peroxide decomposition rates. NFTiO2-containing gels promoted ΔE00 and ΔWID values comparable to those of the commercial 35% HP gel (p > 0. 05), without inducing significant changes in enamel microhardness, surface roughness, surface morphology, or Ca/P ratio after 14 days. These findings demonstrate that HA-based bleaching gels incorporating NFTiO2 nanoparticles can achieve effective tooth bleaching while preserving enamel surface properties, supporting their potential as a safer and efficient alternative in esthetic dentistry.
Melo et al. (Fri,) studied this question.