Acquired Pellicle Engineering in tooth bleaching: analysis of aesthetic efficacy, enamel surface characteristics and treatment cytotoxicity

• Grant number: 24/20549-1
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: August 01, 2025
• End date: December 31, 2027
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: André Luiz Fraga Briso
• Grantee: Karen Milaré Seicento Aidar
• Host Institution: Faculdade de Odontologia (FOA). Universidade Estadual Paulista (UNESP). Campus de Araçatuba. Araçatuba , SP, Brazil

Abstract

Although effective, bleaching treatment can cause damage to tooth enamel and pulp tissue according to the concentration applied. It is speculated that the Acquired Enamel Film (AP) and its modification with a sugarcane-derived cystatin (CaneCPI-5) may increase the resistance of enamel to adverse effects without compromising bleaching efficacy. The aim of this study is to evaluate in vitro the influence of PA modified or not by CaneCPI-5 on in-office bleaching treatment using hydrogen peroxide at different concentrations, considering aesthetic efficacy, substrate alterations, chemical structure and tissue composition, degradation, formation of reactive O2 species and the trans-amelodentinal cytotoxicity of bleaching treatment. To this purpose, bovine enamel and dentin discs will be divided into 9 groups according to the factors under study: 3-level whitening therapy (1- Hydrogen Peroxide 35% gel; 2- Hydrogen Peroxide 9% gel; 3-placebo gel) and 3-level enamel treatment (1- Acquired pellicle; 2- Acquired pellicle enriched with sugarcane-derived cystatin (CaneCPI-5); 3- Deionized water (control)). To evaluate aesthetic efficacy, pigmented specimens (n=12) allocated to the groups will receive three 45-minute bleaching sessions and five readings will be performed on a spectrophotometer (baseline, 24 hours after each session and 14 days after) to calculate the color alteration (¿E00) and whitening index (¿WID). Other specimens will be polished and divided into groups (n=12) to evaluate changes in substrate, chemical structure and tissue composition. Surface roughness and microhardness analyses will be performed before and after 3 bleaching sessions. The specimens will be sectioned for cross sectional microhardness analysis. Other representative specimens (n=3) will be evaluated in ATR-FTIR before and after the sessions. The samples will then be subjected to laser scanning confocal microscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) after treatment. In other specimens, during a bleaching session (n=10), the presence of hydrogen peroxide will be analyzed by permanganatometry and the presence of oxygen reactive species. In addition, cell cytotoxicity tests (n=8) will be performed by quantifying H2O2 diffusion, cell viability tests, Live/Dead, oxidative stress and cell morphology analysis. All the results obtained will be subjected to specific statistical tests with a significance level of 5%. (AU)