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Influence of the violet LED and the horseradish peroxidase enzyme on the aesthetic effectiveness, degradation kinetics and cytotoxicity of bleaching gels

Grant number: 20/08950-1
Support type:Scholarships in Brazil - Master
Effective date (Start): November 01, 2020
Effective date (End): February 28, 2022
Field of knowledge:Health Sciences - Dentistry - Dental Materials
Principal researcher:Carlos Alberto de Souza Costa
Grantee:Beatriz Voss Martins
Home Institution: Faculdade de Odontologia (FOAr). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil

Abstract

The photocatalysis as well as the chemical catalysis of hydrogen peroxide (H2O2) present in bleaching gels composition may improve the aesthetic outcome and reduce the cytotoxicity caused by the conventional in-office bleaching therapy. Thus, the objective of the present study is to evaluate the influence of the application on the enamel, of a protective tape (FP) associated with a polymeric primer (PPol) containing 10 mg/mL of horseradish peroxidase enzyme (HRP) on the bleaching efficacy, degradation kinetics as well the trans-enamel and trans-dentin cytotoxicity of bleaching gels containing 10%, 20% and 35% H2O2, irradiated or not with violet LED. For this purpose, enamel and dentin discs will be subjected to a staining protocol and then exposed to the bleaching protocolsg. As controls, a commercial gel with 35% H2O2 (Whiteness HP, FGM) will be applied for 45 min on enamel or no treatment will be performed. To determine the bleaching efficacy, the enamel of the stained discs will receive FP+PPol, followed by the application of the bleaching gels (45 min), which will be subjected or not to LED irradiation. Then, the discs will be analyzed using a UV-reflection spectrophotometer (CIE L*a*b* system). After that, the degradation rate of residual H2O2 and the production of hydroxyl radicals (OH*) will be assessed. For trans-enamel and trans-dentin cytotoxicity analysis, the same procedures described above will be performed on enamel/dentin discs adapted to artificial pulp chambers. The extracts (culture medium + bleaching gel components diffused across the discs) will be collected and immediately applied on cultured odontoblast-like MDPC-23 cells. Then, these cells will be evaluated concerning their viability (MTT assay), morphology (SEM) and oxidative stress (carboxy-H2DCFDA probe). The quantification of the total H2O2 capable of diffusing through the discs will be also determined (leuco-crystal violet/peroxidase). The numerical data obtained in this laboratorial study will be subjected to specific statistical analysis. (AU)

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