In vitro and ex vivo efficacy and safety evaluation of a bleaching hydrogel containing 3% hydrogen peroxide combined with a doped-biosilicate and irradiated with violet LED light

• Grant number: 24/05339-0
• Support Opportunities: Regular Research Grants
• Start date: March 01, 2025
• End date: February 28, 2027
• Field of knowledge: Health Sciences - Dentistry - Dental Clinics
• Principal Investigator: Vanessa Cavalli Gobbo
• Grantee: Vanessa Cavalli Gobbo
• Host Institution: Faculdade de Odontologia de Piracicaba (FOP). Universidade Estadual de Campinas (UNICAMP). Piracicaba , SP, Brazil
• Associated researchers: Marina Trevelin Souza

Abstract

Despite its proven efficacy, whitening with 35% hydrogen peroxide (H2O2) presents challenges related to pulp cytotoxicity, a fact clinically observed as tooth sensitivity. In a previous study, we observed that a hydrogel consisting of a highly biocompatible glass-ceramic, Biosilicate® (BioS), doped with manganese oxide (MnO2), incorporated with 6% H2O2 and irradiated with violet LED light (LED), promotes whitening effect similar to 35% H2O2, in addition to significantly lower cytotoxicity. However, we found that there is the possibility of increasing the concentration of MnO2 doped to BioS, which could allow further decrease in the concentration of H2O2 (down to 3%), aiming to increasing the safety of H2O2. In this context, this study aims to develop a hydrogel containing BioS doped with a high concentration of manganese oxide (10 wt%), incorporated into 3% H2O2, and irradiated with violet light (LED), and evaluate the whitening efficacy, effect on mineral content and enamel morphology, and in vitro and ex vivo cytotoxicity. In Study 1, BioS_MnO will be synthesized, and the photocatalytic activity will be analyzed. Then, enamel specimens will be treated with (n=10): H2O2 (3% or 6%) combined (or not) with BioS_MnO hydrogel, irradiated (or not) with LED, and compared to H2O2 35% (gel commercial - positive control). Color change will be evaluated [parameters L*, a*, b*, whiteness index for dentistry (”WID) and color variation (”E00)], mineral content [surface microhardness (KHN), carbonate content (CO2-3) and phosphate (PO4-2) in FT-IR spectroscopy], and surface morphology (SEM). In Study 2, the specimens will be adapted in artificial pulp chambers (CPAs) and subjected to treatments with (n=8): H2O2 3%_BioS_MnO and H2O2 (irradiated or not) and H2O2 35%. The diffusion of H2O2 (ug/mL), and cytotoxicity of the gels will be determined [(MTT, oxidative stress (OxS), cellular morphology, and cellular predictions (alive/dead)). In Study 3, molars from Wister rats will be submitted for treatment. In all studies, bleaching will be carried out in 3 sessions of 30 minutes with an interval of 7 days and data will be subjected to statistical analysis, with appropriate tests considering normality (± = 5%). (AU)