Development, characterization and clinical application of hydrogen peroxide-free whitening gels

• Grant number: 24/08870-9
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: February 01, 2025
• End date: January 31, 2027
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Carlos Alberto de Souza Costa
• Grantee: Rafael Antonio de Oliveira Ribeiro
• Host Institution: Faculdade de Odontologia (FOAr). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil

Abstract

The main objective of the present study is to develop innovative in-office whitening gels containing peroxymonosulfate (PMS) and peroxydisulfate (PDS). It will be assessed their whitening efficacy, consequences on enamel structure, trans-enamel/trans-dentin cytotoxicity, effects on gene expression of markers by pulp cells (in vitro sections), as well as the post-whitening tooth sensitivity and aesthetic outcome (clinical section). Initially, 50 experimental groups will be established, combining different concentrations of PMS/PDS and manganese dioxide (MnO2). The concentrations of PMS/MnO2 and PDS/MnO2 will be determined by potentiometric titration of each gel, and their chromophores degradation effects will be evaluated to obtain the best combination of both oxidants agents, which will be assessed in following laboratory tests. Standardized enamel/dentin discs will be stained and the most promising experimental gels will be applied for 45-minute (1 session) on enamel. A whitening gel with 35%H2O2 will be used as positive control, while "no treatment" will be employed as negative control. The whitening efficacy will be evaluated using a UV reflection spectrophotometer (CIE Lab System*). Subsequently, the same treatments will be carried out to evaluate the microhardness and possible morphological changes in tooth enamel, using Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometry (EDS). To analyze the indirect cytotoxicity, stained enamel/dentin discs will be adapted into artificial pulp chambers, and the whitening gels applied on enamel surface for 45 minutes. Thus, the extracts (culture medium + components of the whitening gels diffused through the discs) will be collected and immediately applied to odontoblast-like MDPC-23 cells, which will be evaluated concerning their viability (MTT), oxidative stress (carboxy-H2DCFDA probe) and morphology (SEM). The amount of H2O2 diffused across the discs will also be determined (Leuco-crystal violet/Peroxidase). Furthermore, the cells will be evaluated (immediately and after 7 days) for gene expression of the following markers: Tnf; Ptgs2; Ilb, Il6, Il17d, Il23a; Hmox1; Bglap, Spp1, Alpl; Dspp e Dmp1. After concluding the in vitro protocols, the best whitening therapies obtained will be assessed by clinical trial. In this last section of this project, the tooth chromatic changes, as well as degree of post-whitening tooth sensitivity and satisfaction of patients will be evaluated. The numerical data obtained will be subjected to specific statistical analysis.