Chemical catalisis of hydrogen peroxide in bleaching agents: analysis of esthetic and biologic effects

• Grant number: 15/20782-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): December 01, 2015
• Effective date (End): November 30, 2016
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Carlos Alberto de Souza Costa
• Grantee: Natália Marcomini
• Host Institution: Faculdade de Odontologia (FOAr). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil

Abstract

Chemical catalysis of hydrogen peroxide (H2O2) on bleaching gels has emerged as an interesting alternative to minimize H2O2 diffusion through dental structure and increase bleaching effectiveness. However, only few studies have demonstrated the biologic effects of this procedure on pulp cells. Therefore, in present investigation the trans-enamel and trans-dentinal cytotoxicity, H2O2 diffusion and bleaching effectiveness of a 35% H2O2 bleaching gel associated or not to chemical activators will be evaluated. For that, enamel/dentin discs will be subjected to bleaching (3x 15 minutes) with a 35%- H2O2 gel containing manganese chloride, peroxidase or catalase. The gel with no chemical activator will be used as a positive control, and no treatment will be performed on negative control group. The color alteration will be measured by means of UV-Vis spectrophotometer according to the CIE L*a*b* system. In order to evaluate the trans-enamel and trans-dentinal cytotoxicity, the discs will be adapted to trans-well devices, which will be placed over MPDC-23 odontoblast-like cells seeded on culture plates at 80% confluence. Immediately after bleaching, the cell viability (MTT assay) and oxidative stress (H2DCFDA fluorescence) will be evaluated. The H2O2 capable to diffuse through the discs will be quantified (leuco-crystal violet/peroxidase assay). Data will be subjected to specific statistical analysis.