Bioceramic characterization of calcium phosphates microstructured in different composition in sheep

Abstract

Microporous bioceramics of calcium phosphate and biphasic hydroxyapatite and tricalcium phosphate beta (HA/TCP- β) in the form of microporous granules biomaterials are research subjects and stand out as bone substitutes in biomedical application. The biphasic bioceramics are biocompatible, bioactive, osteoinductive and promote osseointegration when applied in vivo or through simulated. Another aspect of such differential solubility bioceramics is associated with the capacity that these biomaterials exhibit when applied in biological environment, enabling the gradual release of calcium and phosphate ions to the biological environment they are absorbable and promote neogenesis of new bone tissue. The biphasic bioceramics of calcium phosphate also have promising applications in traumatology in the repair of injured bone and controlled release of drugs in the bone structure treatments. The performance of these biomaterials as bone substitutes and controlled release of drugs, are associated, their physical, chemical, morphological and surface. The aim of this study was to make morphological, microstructural of biomaterials by the technique of scanning electron microscopy (SEM), physics with X-ray diffraction (XRD) and Arthur method for determination of open porosity. The theoretical density of biphasic biomaterials was determined by theoretical method of biphasic concentrations. Finally, we conducted evaluation of osteogenesis and osseointegration behavior of different biomaterials of calcium phosphates in vivo tests on sheep. In vivo tests were performed on tibias of sheep up to of 03 months. The biomaterials implanted were hydroxyapatite (HA), tricalcium phosphate-β (β-TCP) and biphasic compositions as HA/TCP-β in rates: 80/20, 20/80, 70/30 and 30/70. Eight crossbred Texel sheep, with 12 months of age and average weight of 30 kg (±5 kg) were used, in which were produced three bone defects in the tibia, four of these defects were filled with biomaterials, and two by bone fragments (autograft), as control group. The animals were euthanized at 03 months after implantation of biomaterials. After euthanasia, the tibias were collected for evaluation using the scanning electron microscopy technique (SEM). The results show that the microporous biomaterial granules are formed by an irregular morphology with grain size between 200 μm and 500μm, another finding was microporous interconnected microstructure of biomaterials. The result showed that the open porosity of the biomaterials exhibit porosity greater than 68%. The theoretical density was relatively similar between the granulates biomaterials of calcium phosphates and suggest good capacity of osteogenesis for all biomaterials, with the biphasic absorption of the biomaterial introduced 20/80 and more rapid bone formation when compared with other biomaterials evaluated in study.