Characterization and effects on enamel of low-concentration bleaching gels containing hyaluronic acid, NF_TiO2 nanoparticles and irradiated with violet LED light

Resumo (EN)

Objective: To characterize and evaluate experimental in-office bleaching gels containing hyaluronic acid (HA) or carbomer 940 (CAR), enriched with NF_TiO₂ nanoparticles and irradiated with a violet LED, assessing their effects on the physicochemical properties of enamel.

Materials and methods: Bovine enamel-dentin discs were treated according to the parameters: thickener (HA or CAR), HP concentration (1.5% or 6%), and irradiation (with or without LED), resulting in 9 experimental groups (n = 10/group). An additional control group (35%HP-commercial) was adopted, and three sessions were conducted (30 min each, with a 7-day interval). Gels were evaluated for pH, particle size, polydispersity index, zeta potential and rheological behavior. Samples were assessed for color change (ΔE00), whiteness index (ΔWID), Ca/P ratio (EDS), surface microhardness (KHN), roughness (ΔRa), and surface morphology (SEM). Data were analyzed using ANOVA three-way and Tukey/Bonferroni (α = 5%).

Results: pH remained stable above 6.0. Hyaluronic-based gels exhibited higher particle size and polydispersity, but lower zeta potential and less viscous rheological behavior compared to the carbomer-based ones (p 0.05). Hyaluronic-based gels groups irradiated with LED increased Knoop microhardness (p 0.05).

Conclusion: Experimental hyaluronic or carbomer bleaching gels incorporated with NF_TiO2 nanoparticles and irradiated with violet LED showed minimal variations in physicochemical properties, effective bleaching even at low HP concentrations, and no enamel damage.

Clinical relevance: Innovative bleaching gel formulations incorporating hyaluronic acid, NF_TiO₂ nanoparticles, and violet LED light irradiation exhibit high efficacy even at low hydrogen peroxide concentrations, thereby minimizing enamel damage and potentially mitigating post-operative sensitivity.