Abstract
With the advancement of research in biomaterials, it has been suggested that the best osteoconductivity of hydroxyapatite would be achieved if its crystal were closer to the structure, size and morphology of biological apatite, that is why nano-hydroxyapatite (nano-HA) is of great importance. current interest. Strontium ions are known to reduce bone resorption, induce osteoblastic activity and stimulate bone formation. The aim of this study was to evaluate biocompatibility and osteoconduction in surgical defects filled with nano-hydroxyapatite microspheres containing 1% strontium (nano-SrHA), stoichiometric nano-HA microspheres (nano-HA) compared to the clot (control) . Four Santa Inês sheep, weighing an average of 32 kg, were anesthetized and submitted to three 2 mm diameter perforations in the medial face of the tibia. The surgical defects were filled with blood clot, microspheres of Sr-HA 1% and microspheres of HA. After 30 days the samples were drawn (6 mm), decalcified, processed for inclusion in paraffin and stained with hematoxylin and eosin (HE) for histological evaluation with light microscopy. All groups revealed bone neoformation from the periphery to the center of the defect, with the nano-SrHA group being less intense among those studied. Presence of a discrete mononuclear inflammatory infiltrate in all experimental groups. Giant foreign body cells were only observed in the HA group. Areas of bone neoformation were observed in close contact with both biomaterials. According to the results obtained, microspheres of HA and SrHA 1% are biocompatible and have osteoconductive properties.
Highlights
Localized bone defects can occur as a result of infections, pathological processes, congenital injuries, traumatic injuries or even due to tooth extractions and generally interfere with the installation of implants and prosthetic rehabilitation
With the objective of restoring and preserving the alveolar bone morphology, new materials and techniques have been the target of research aimed at providing the development of a set of procedures and biomaterials that optimize the performance of this rehabilitation 10,12
HA has been widely used as an important bone substitute and is distinguished from other calcium phosphate-based ceramics because it is similar to the inorganic portion of bone tissue, biocompatible, mechanically resistant, bioactive, non-toxic, radiopaque, allowing periodic monitoring through imaging tests, cause little tissue reaction and not be antigenic or carcinogenic, in addition to having a great capacity for protein adsorption on its surface 15
Summary
Localized bone defects can occur as a result of infections, pathological processes, congenital injuries, traumatic injuries or even due to tooth extractions and generally interfere with the installation of implants and prosthetic rehabilitation. Strontium (Sr) is present in the mineral phase of bones, especially in regions with greater metabolic function 2; its content in the new compact bone is three to four times higher than that of an old compact bone, and approximately 2.5 times higher in the new cancellous bone than in the oldest 11. As it increases the activity of osteoblasts and decreases the activity of osteoclasts, Sr has an anti-resorptive and bone-forming effect in vitro 3. The aim of this study was to perform a subjective histological evaluation of bone repair in sheep tibias 30 days after implantation of microspheres of nanohydroxyapatite (nano-HA) and nano-HA containing 1% strontium (nano-SrHA) in comparison clot (control)
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