Banca de QUALIFICAÇÃO: AGNES ANDRADE MARTINS

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : AGNES ANDRADE MARTINS
DATE: 09/12/2024
TIME: 14:00
LOCAL: PLATAFORMA VIRTUAL
TITLE:

Physical and in vivo evaluation of a Hydroxyapatite-Silver composite for bone regeneration

KEY WORDS:

Biomaterial. Bone Regeneration. Hydroxyapatite. Silver. Inflammation.

PAGES: 46
BIG AREA: Ciências da Saúde
AREA: Odontologia
SUMMARY:

Introduction: Repairing large bone defects in the craniofacial region is a challenge in the context of tissue regeneration. Inherent limitations of autologous grafts render the use of synthetic grafts more convenient, with a special emphasis on hydroxyapatite (HAp), a calcium phosphate that is similar to natural bone. The association of HAp with other materials seeks to overcome the limited mechanical properties of HAp, which may compromise its performance in extensive lesions or those susceptible to mechanical stress. Silver (Ag) is a metal with a well-established antimicrobial activity and has been demonstrating promising osteogenic performance. Objective: To characterize the physical properties of a novel Hap-Ag composite and evaluate its biological performance in an experimental model of critical-size calvarial defect. Methodology: HAp and Hap-Ag powders were obtained and analyzed for morphology by a Scanning Electron Microscope (SEM). Cylindrical pellets obtained from the press and sintering of the powders were subjected to X-ray diffraction (XRD) evaluation to characterize the crystalline phases, and to the Vickers microhardness test to analyze the fracture toughness. For the in vivo experiment, 36 male Wistar rats were subjected to the surgery of an 8 mm critical calvaria defect and randomly distributed into three groups (n = 12/group): Control group (CG), untreated defect; HAp group, defect filled with HAp pellet; and Hap-Ag group, defect filled with Hap-Ag pellet. After 90 days of surgery, the animals were euthanized, and calvaria samples were collected and sent for analysis by computerized microtomography (µ-CT), histological analysis including hematoxylin and eosin staining and immunohistochemistry (osteopontin and osteocalcin), quantification of proinflammatory cytokines (IL-1β, TNF-α and IL-6) and relative gene expression (BMP-2, RUNX2, Procollagen 1 and 3, TGF-β, Osterix and eNOS). Data obtained were evaluated by analysis of variance (ANOVA) followed by Tukey's post-test (normal distribution) or by the Kruskall-Wallis test followed by Dunn's post-test (non-normal distribution), with a significance level set at 5%. Partial results: Compared to the Control group, defects filled with both biomaterials showed greater bone formation (BV/TV%). The new bone showed less porosities, and a greater number of trabeculae and less trabecular separation. Histological analysis revealed a more advanced stage of bone maturation in the animals in the Hap-Ag group compared to the GC (p<0.05). Higher levels of TNF-α were observed in the Hap-Ag group, in relation to the GC (p<0.05), and of IL-1β in relation to the other groups (p<0.05). A higher gene expression of the pro-collagen 3 (p<0.05) and eNOS (p<0.01) markers was observed in the animals treated with the Hap-Ag composite in comparison to the GC group.

COMMITTEE MEMBERS:
Presidente - 1958729 - RUTHINEIA DIOGENES ALVES UCHOA LINS
Interno - 2220417 - CARLOS AUGUSTO GALVAO BARBOZA
Interna - 1121806 - MARIA LUIZA DINIZ DE SOUSA LOPES