Titanium dioxide nanotubes (TiO2) incorporated into bleaching agents for in-office use associated to violet light: physicochemical properties of bleaching gel, enamel color change, pulp chamber temperature, and cell cytotoxicity

Abstract

The present study aims to evaluate the physical-chemical properties of in office bleaching agents incorporated with titanium dioxide nanotubes (TiO2), associated or not with violet light applications and the effects regarding dental structure alteration at different times, pulp temperature and biocompatibility with cell culture. Bleaching agents with 35% hydrogen peroxide (PH) (Whiteness HP, FGM) and 6% (white class, FGM), incorporated or not with 1% TiO2, associated or not with a violet led light application will be evaluated. In order to evaluate the physical-chemical properties of the bleaching gel, the pH value, mass analysis, hydrogen decomposition, medium particle size (P), Polydispersibility (PO) and zeta potential (PZ) will be measured. For color analysis (Vita Classical scale and CIEDE 2000), 60 bovine incisors will be prepared and divided into six groups (n = 10). Bleaching agents will be used with or without application of Bright Max Whitening (MMOptics) LED light in three 30-minute sessions, with a 7-day interval between sessions. The measurements will be performed at different times (baseline, 24 hours after, 8th day, 15th day, 1 week and 1 month after the end of treatment). For an evaluation of the pulp temperature (using a thermocouple inside the pulp chamber), 60 bovine incisors with palatal access, and buccal face with a thickness of 2.5 mm will be used and distributed among the same groups. Temperature measurements will be made during and after bleaching treatment. For an evaluation of cytotoxicity, pulp fibroblast and odontoblast cell culture will be used. Cells will be seeded in 96-well plates (1 x 103 cells/well) and placed in contact with the bleach conditioned culture medium (PH 35% group, PH 6% group, nanotube-added PH 6% group) with an application or not of the violet led light for 30 minutes. Cell viability will be analyzed by MTT reduction test and cell proliferation will be done by Trypan blue vital exclusion method, detected immediately and 24 hours after treatment. For all studied variables, data will be tabulated in electronic electronics, applying parametric or nonparametric tests. A significance level of 5% will be adopted. (AU)