![]() ![]() It was found that the samples are solid solutions based on octacalcium phosphate pentahydrate (Ca 8H 2(PO 4) 6♵H 2O) and correspond to card № 26-1056 of the XRD base ICDD (Powder Diffraction File, Alphabetical Index Inorganic Compounds, Pensylvania: JCPDS, 1997). XRD patterns of obtained OCP and OCP-Sr are shown in Figure 1. Strontium ions in calcium phosphate contribute to the improvement of osteoblast function and subsequent bone formation. Strontium-containing materials optimize osseointegration on the initial stages, shifting the balance between osteoplastic synthesis and osteoclastic resorption. The process of reparative osteoregeneration begins with the intensification of the proliferative activity of osteoblasts. Its osteoinductive properties are important, which are proposed to be improved by substitution of calcium for strontium. Since the low-temperature OCP considered in this work has a suitable bioresorption rate, the currently unsolved problem is to increase the biological properties of the obtained material. Thus, it is possible to obtain materials based on calcium phosphates with both high bioactivity and antibacterial properties. At the same time, depending on the nature and concentration of the embed ion, both improvement and deterioration of the functional properties of the implant is possible. There is no unambiguous opinion about the role of ionic substitutions in the physiology of bone tissue, but it has been revealed that it is possible to change and improve the properties of materials due to structural substitutions with cations and anions. The maim interest in materials for bone tissue regeneration based on OCP is also associated with its structural characteristics, which allow the introduction of cations and anions, as well as biological agents for targeted functionalization. First, such materials include OCP, which, unlike other analogs, has a high resorption rate and pronounced osteoinductive potencies. It was previously described that these materials, synthesized under conditions as close as to natural biominerelization processes, can have a direct inducing effect. ![]() Therefore, a promising approach for dental or orthopedic reconstructive surgery is using the low-temperature calcium phosphate ceramics, which are the most appropriate as possible to the components of the native bones, in particular apatite-like hydroxyapatite (HAp) and its possible precursors-dicalcium phosphate dihydrate (DCPD) and octacalcium phosphate (OCP). It is well-known that calcium phosphate materials obtained by high-temperature routes are biocompatible, non-toxic, but devoid of the possibility of biointegration, have a low rate of resorption and can cause fibrous encapsulation of the entire material at the site of implantation. The presence of calcium and its release from the material during the healing process can mediate the expression of osteopontin, which binds to bone hydroxyapatite, participates in its formation, and has an integrin-binding domain, which promotes cell proliferation on the implant surface. The presence of calcium and phosphorus ions in the composition of these materials imparts osteoconductive properties to the implant. This led to the development of matrices and scaffolds with specified physicochemical properties based on biocompatible calcium phosphates-hydroxyapatite and tricalcium phosphate. A large number of works are devoted to bioresorbable materials for maximum imitation of the structure and properties of native bone tissue. The bones regeneration processes studies, rather than mechanical replacement of bone tissue, lead to the creation of various combinations of materials based on calcium phosphate ceramics and its composites for bone augmentation procedures. The results of the study indicate the effectiveness of using strontium in OCP for improving biocompatibility of OCP based composite materials intended for bone repair. The effect of strontium substitution range on changes in the crystal lattice of materials, the microstructural features, surface morphology and biological properties in vitro has been established. ![]() The processes of phase formation of low-temperature OCP with theoretical substitution of strontium for calcium up to 50 at.% in conditions close to physiological, i.e., temperature 35–37 ☌ and normal pressure, were described. Strontium was inserted into the OCP structure by ionic substitution in solutions. Strontium is used to improve bioactive properties of the material. In this work, the synthesis of low-temperature calcium phosphate compounds and substituted forms of those at physiological temperatures is shown. ![]() OCP has higher biocompatibility and osseointegration rate compared to other calcium phosphates. Octacalcium phosphate (OCP, Ca 8H 2(PO 4) 6♵H 2O) is known to be a possible precursor of biological hydroxyapatite formation of organic bone tissue. ![]()
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