Polycaprolactone-nanohydroxyapatite nanofiber scaffolds for regeneration of the pulp-dentin complex: synthesis, characterization and biological behavior in human teeth culture

• Grant number: 19/16473-1
• Support Opportunities: Regular Research Grants
• Duration: May 01, 2020 - August 31, 2022
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Josimeri Hebling Costa
• Grantee: Josimeri Hebling Costa
• Host Institution: Faculdade de Odontologia (FOAr). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil

Abstract

Although there are dental materials with clinical acceptable performance when applied on direct contact with the pulp tissue, these calcium hydroxide-based materials cause, initially, tissue necrosis and cell death. The growth in the knowledge of pulp biology plus the remarkable progress in the field of tissue engineering and biotechnology have made possible the development of biocompatible and bioactive materials to regenerate the pulp tissue. Based on this premise, this research aims to develop a polycaprolactone nanofiber scaffold (PCL) incorporated with nano-hydroxyapatite (nHA), that presents the potential to stimulate cell migration (chemotaxis) and differentiation into odontoblast cells to regenerate the pulp-dentin complex when applied on pulp exposures. In the first experiment, PCL scaffolds containing different concentrations of nHA (0, 0.5, 1 and 2%) will be produced, characterized as to the morphology (distribution, size and connectivity of the interfibrillar spaces), and evaluated regarding their hydrolytic degradation (mass loss), change in the medium pH and calcium release. Additionally, PCL-nHA scaffolds will be seeded with human dental pulp cells (HDPCs) to analyze the cell viability (alamarBlue), adhesion and spreading (F-actin), cellular proliferation (live/dead assay), activity of alkaline phosphatase, formation of mineralized nodules (Alizarin red) and gene expression (PCR) for odontoblast phenotype. In the second study, PCL-nHA scaffolds will be applied as direct capping materials using a human teeth cell culture model. The best concentration of nHA will be selected based on the results of the first study. Therefore, the apical half of newly extracted human molars will be removed and class I cavities will be prepared on the occlusal surfaces until the pulp tissue is exposed. The following materials will be applied in direct contact with the exposed pulp tissue: calcium hydroxide paste (control), PCL scaffold with no nHA, PCL scaffold de PCL with nHA or only a Teflon disk. Additional teeth will be kept sound for internal validation of the methodology. All teeth will be placed in a culture model to maintain the vitality of the pulp tissue. After 28 days, the teeth will be prepared for histopathological analysis and compared with teeth treated with calcium hydroxide paste (control treatment). The number of replicates will vary according to the experimental protocol. Data will be submitted to specific statistical analyses, at the 5% level of significance, after determining the type of distribution and whether homoscedasticity is confirmed or not. (AU)