Characterization, bleaching efficacy and safety of an experimental gel containing 3% hydrogen peroxide combined with a biosilicate doped with manganese oxide and irradiated by violet LED

• Grant number: 24/23556-9
• Support Opportunities: Scholarships in Brazil - Master
• Start date: July 01, 2025
• End date: February 28, 2027
• Field of knowledge: Health Sciences - Dentistry - Dental Clinics
• Principal Investigator: Vanessa Cavalli Gobbo
• Grantee: Guilherme Silva dos Santos
• Host Institution: Faculdade de Odontologia de Piracicaba (FOP). Universidade Estadual de Campinas (UNICAMP). Piracicaba , SP, Brazil

Abstract

Despite its proven efficacy, dental bleaching with 35% hydrogen peroxide (HP) poses challenges due to pulp cytotoxicity. In this context, the incorporation of manganese oxide (MnO2 10 wt%) doped into Biosilicate® (BioS) emerges as a promising alternative, allowing the reduction of HP concentration to 3% while maintaining bleaching efficacy and minimizing cytotoxic effects. This study proposes the development of an experimental gel containing BioS doped with a high concentration of MnO2 (10%wt), combined with 3% HP and irradiated with violet LED. The study aims to characterize the chemical and physical properties of the experimental gel and evaluate ts bleaching efficacy, effects on mineral content, enamel morphology, and cytotoxicity. In Study 1, BioS_MnO2 will be synthesized. Subsequently, pH, bleaching agent decomposition, particle size and organization (polydispersity and transmission electron microscopy), colloidal stability (zeta potential), viscosity (measured with a viscometer) will be evaluated. In Study 2, enamel specimens will be treated (n=10) with: HP (3% or 6%) combined (or not) with BioS_MnO2 gel, irradiated (or not) with violet LED, and compared to 35% PH (commercial gel - positive control). The study will assess color change [L*, a*, b* parameters, whiteness index (¿WID) and color variation (¿E00)], mineral content [surface microhardness (KHN), roughness (Ra), carbonate (CO32-) and phosphate (PO43-) content using FT-IR spectroscopy], and surface morphology (SEM). Study 3 will adapt specimens in artificial pulp chambers (APCs) and subjected them to the same bleaching treatments (n=8) as in Study 2. Color analysis, HP diffusion (¿g/mL) and gel cytotoxicity will be determined [(MTT, oxidative stress (OxS), cell morphology and viability assays (live/dead)]. Data will undergo statistical analysis using appropriate tests, considering normality and homoscedasticity (¿ = 5%). (AU)