Caracterização física e avaliação in vivo de um scaffold de hidroxiapatita/nióbio

Abstract

Hydroxyapatite (Hap) is a highly trained compound used for clinical use, due to the treatment of a mineral component present in the formation of bones, its use provides conditions for bone growth, thus allowing the biological fixation of grafts that are widely used for reconstructions of organic tissues, very little progress has been made in relation to materials capable of fulfilling with excellence the function of a material that is capable of having an osseointegration characteristic, in this sense the search for new constituent elements of the grafted pieces appears as a motivation of studies, as it provides the patient with an option to choose their treatments. In this sense, a Hydroxyapatite/Niobium compound was considered as a bioceramic material, it was characterized in terms of its morphology [X-ray diffraction (XRD), tension, cracking and tenacity and analyzed in vivo in a skullcap model with 8 mm critical defect performed in Wistar rats, with 3 experimental groups: Control (GC) - (positive control); Hap (hydroxyapatite standard) and (CNb/CPO - Hydroxyapatite/Niobio). After 90 days, the animals were euthanized and the samples were evaluated using Micro CT, HE and immunohistochemistry. The data obtained were statistically evaluated using the ANOVA test and the results were: In the mechanical results of XRD, the presence of hexagonal crystalline Hap and a P63/m space group was observed in the pure sample, while in the group with Nb, the presence of β-tricalcium phosphate (Ca3(PO4)2) and Fersmite (CaNb2O6), which may be related to the decomposition of Hap in the presence of Nb. In the XRF analysis, results close to those of grinding were obtained, proving that the technique used was efficient. Regarding the presence of indentations and cracks, there was a small increase in fracture toughness from Hap (0.78 MPa.m1/2) to Hap/Nb (0.82 MPa.m1/2). As in vivo results: micro-CT showed an increase in trabecular number (p˂0.001), a decrease in porosities (%) (p˂0.001) and a decrease in trabecular separation (mm) (p˂0.001) in the CNb/CPO group in comparison to the CG group. In the CNb/CPO group, there was the presence of new bone in which the connective tissue differentiates to form or indicate a bone matrix score of 3 (3-3.75, p˂0.05) and strong immunoexpression of osteopontin (p<0, 05). The results indicate that CNb/CPO showed resistance to crack propagation and stimulated bone formation in calvarial defects in rats.