Biomineralization and dentin adhesion of a hydraulic cement functionalized with aspartic acid

• Grant number: 25/05423-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2025
• End date: May 31, 2026
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Walter Raucci Neto
• Grantee: Victor Miguel Polizeli
• Host Institution: Faculdade de Odontologia de Ribeirão Preto (FORP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

This project aims to evaluate the effect of an aspartic acid (AA) solution on the physicochemical properties, biomineralization, and dentin adhesion of a hydraulic cement for direct pulp capping (MTA, Angelus). The MTA will be mixed with a 4 g/L aspartic acid solution in five different proportions, forming five experimental groups: 0% (control, containing 100% distilled water - DW), 25% (25% AA and 75% DW), 50% (50% AA and 50% DW), 75% (75% AA and 25% DW), and 100% (100% AA and 0% DW). Setting time and solubility analyses will be performed using 10 specimens from each of the five evaluated cement groups (n=10). To assess apatite formation, 20 cylindrical samples (2 mm in height and 4 mm in diameter) will be obtained for each cement group. These samples will be divided into two subgroups (n=10) and stored in either deionized water or phosphate-buffered solution. The solutions will be renewed every 72 hours, totaling 30 days of storage. Chemical characterization of the cement surface will be performed using energy-dispersive X-ray spectroscopy (EDS-X) and Fourier-transform infrared spectroscopy (FTIR), while morphological characterization will be conducted using scanning electron microscopy (SEM) and confocal laser microscopy (CLM). To evaluate bond strength and chemical adhesion to dentin, 50 slices of bovine coronal dentin will be prepared, each containing a cylindrical cavity of 2 mm in diameter. These slices will be distributed among the five cement groups (n=10). After being filled with their respective cements, the samples will be stored in PBS for 30 days and then subjected to a push-out test in a universal testing machine at a speed of 1 mm/min. Failure mode analysis will be conducted using a stereoscopic magnifying glass and classified as adhesive, cohesive, or mixed. The obtained data will be analyzed quantitatively, using a significance level of 5%. The findings of this study will help elucidate the relationship between the physicochemical modifications of the cement associated with different AA concentrations, its interaction with dentin, and its potential impact on the biological properties of the materials, simulating clinical conditions.