Banca de QUALIFICAÇÃO: FÁBIO MIGUEL SANTOS COSTA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : FÁBIO MIGUEL SANTOS COSTA
DATA : 26/11/2018
HORA: 09:00
LOCAL: Sala Carl Peter von Dietrich - Departamento de Bioquímica
TÍTULO:

Characterization of the osteogenic and genotoxic effect of extracts of endodontic cements reinforced with nanohydroxyapatite

PALAVRAS-CHAVES:

Keywords: Stem cells, endodontic sealers, osteoblastic differentiation, genotoxicity

PÁGINAS: 112
GRANDE ÁREA: Ciências Biológicas
ÁREA: Bioquímica
RESUMO:

Nowadays, millions of endodontic treatments of caries and bacterial infections are performed. After the pulp infection, all tissues of the root canals are removed, using adequate instrumentation, irrigation and antimicrobial substances. Next, apexification and obturation are performed to complete the three-dimensional sealing of the system with endodontic sealers that provide a barrier to periapical tissues, preventing the development of a chronic inflammatory process. Despite their clinical success, the commercial sealers do not meet the all the requirements of an ideal endodontic sealer, namely the induction capacity of the periradicular regenerative process that requires the recruitment of mesenchymal stem cells/osteoblastic precursor cells and their differentiation into osteoblasts for synthesis of the mineralized matrix. The incorporation of hydroxyapatite (HAp), similar to the mineral phase of bone, into dental materials begins to be a promising approach, to improve the mechanical and biological characteristics of the product. The objective of this work was to verify the osteogenic and genotoxic effects of the extracts of resin-based endodontic cement (AH Plus, 1:10 and 1: 100) reinforced with two concentrations (10 and 100 μg/mL) of hydroxyapatite nanoparticles (NHAp) or zinc functionalized hydroxyapatite nanoparticles (NHAp-Zn3 and NHAp-Zn5). For this purpose, human mesenchymal stem cells from Wharton jelly (hMSC-WJ), CHO-K1 cells and FMM1 cells were used, respectively. MTT assay showed that NHAp with or without zinc reduced viability by 40% in 14 days of culture. The extract of the AH Plus (1:10) showed to be quite toxic, however, in the presence of NHAp, with and without zinc, the viability increased, with the result being better in the presence of the most diluted extract (1:100). The mineralization assay, measured both by the extracellular matrix staining by Alizarin red and by the measurement of calcium accumulation, showed that NHAp improves osteogenesis, especially in the osteogenic medium, with NHAp-Zn3 in the lowest concentration more effective than NHAp-Zn5. In relation to genotoxicity, the results of cytokinesis-block micronucleus (CBMN) assay showed that NHAp in the presence or absence of zinc 3 did not show a significant increase in the frequency of micronuclei (MN), nuclear buds (NBUD) and/or nucleoplasmic bridges (NPB). The results suggest that NHAp improves osteogenesis in osteogenic medium without showing genotoxicity indicating that they may be an alternative for bone regeneration therapies in endodontic treatment.

MEMBROS DA BANCA:
Externo ao Programa - 2220417 - CARLOS AUGUSTO GALVAO BARBOZA
Externo à Instituição - DAIANE CRISTINA FERREIRA GOLBERT - UFRN
Presidente - 1046922 - LEONARDO CAPISTRANO FERREIRA