Interest in calcium phosphate cements as materials for the restoration and treatment of bone tissue defects is still high. Despite commercialization and use in the clinic, the calcium phosphate cements have great potential for development. Existing approaches to the production of calcium phosphate cements as drugs are analyzed. A description of the pathogenesis of the main diseases of bone tissue (trauma, osteomyelitis, osteoporosis and tumor) and effective common treatment strategies are presented in the review. An analysis of the modern understanding of the complex action of the cement matrix and the additives and drugs distributed in it in relation to the successful treatment of bone defects is given. The mechanisms of biological action of functional substances determine the effectiveness of use in certain clinical cases. An important direction of using calcium phosphate cements as a carrier of functional substances is the volumetric incorporation of anti-inflammatory, antitumor, antiresorptive and osteogenic functional substances. The main functionalization requirement for carrier materials is prolonged elution. Various release factors related to the matrix, functional substances and elution conditions are considered in the work. It is shown that cements are a complex system. Changing one of the many initial parameters in a wide range changes the final characteristics of the matrix and, accordingly, the kinetics. The main approaches to the effective functionalization of calcium phosphate cements are considered in the review.

Ceramic samples based on β-calcium pyrophosphate β-Ca₂P₂O₇ were prepared from powders of γ-calcium pyrophosphate γ-Ca₂P₂O₇ with preset molar ratios Ca/P = 1, 0.975 and 0.95 using firing at 900, 1000, and 1100 °C. Calcium lactate pentahydrate Ca(C₃H₅O₃)₂⋅5H₂O and monocalcium phosphate monohydrate Ca(H₂PO₄)₂⋅H₂O were treated in an aqua medium in mechanical activation conditions to prepare powder mixtures with preset molar ratios Ca/P containing calcium hydrophosphates with Ca/P = 1 (precursors of calcium pyrophosphate Ca₂P₂O₇). These powder mixtures containing calcium hydrophosphates with Ca/P = 1 and non-reacted starting salts were heat-treated at 600 °C after drying and disaggregation in acetone. Phase composition of all powder mixtures after heat treatment at 600 °C was presented by γ-calcium pyrophosphate γ-Ca₂P₂O₇ according to the XRD data. The addition of more excess of monocalcium phosphate monohydrate Ca(H₂PO₄)₂·H₂O (with appropriate molar ratio of Ca/P = 1) to the mixture of starting components resulted in lower dimensions of γ-calcium pyrophosphate (γ-Ca₂P₂O₇) individual particles. The grain size of ceramics increased both with the growth in firing temperature and with decreasing molar ratio Ca/P of powder mixtures. Calcium polyphosphate (t _melt = 984 °C), formed from monocalcium phosphate monohydrate Ca(H₂PO₄)₂⋅H₂O, acted similar to a liquid phase sintering additive. It was confirmed by tests in vitro that prepared ceramic materials with preset molar ratios Ca/P = 1, 0.975, and 0.95 and phase composition presented by β-calcium pyrophosphate β-Ca₂P₂O₇ were biocompatible and could maintain bone cells proliferation.

Titanium membranes and meshes are used for the repair of trauma, tumors, and hernia in dentistry and maxillofacial and abdominal surgery. But such membranes demonstrate the limited effectiveness of integration in recipients due to their bioinertness. In this study, we prepared titania oxide (by microarc oxidation) and/or HAp (by electrophoresis deposition) coatings with alginate soaking. We used annealing at 700 °C for 2.5 h for HAp crystallinity increasing with achievement of an acceptable Ca²⁺ release rate. The feedstock HAp and prepared coatings were characterized by X-ray diffraction, IR spectroscopy, electron and optical confocal microscopy, and thermal analysis, as well as the in vitro study of solubility in saline and in vivo tests with the animal model of subcutaneous implantation (with Wistar rats). Biocompatible compounds were found for all deposited coatings. We noted that the best biological response was detected for the annealed Ca-P/TiO₂ bilayer with alginate binding. In this case, the coating crystallinity was ≈40.5-50.0%. The Ca²⁺ release rate was 2.042 ± 0.058%/mm² at 168 h after immersion in saline. Thin and mature tissue capsules with minimal inflammation and vascularization were found in histological sections. We did not detect any unwanted responses around the implants, including inflammation infiltration, suppuration, bacterial infections, tissue lyses, and, finally, implant rejection. This information is expected to be useful for understanding the properties of bioactive ceramic coatings and improving the quality of medical care in dentistry and maxillofacial surgery and other applications of titanium membranes in medicine.

Low-temperature ceramics based on magnesium calcium phosphate cement are a promising resorbable material for bone tissue restoration with the possibility of functionalization. The replacement of the magnesium Mg²⁺ ion with a calcium Ca²⁺ ion at the stage of preparation of the precursor leads to the production of multiphase ceramics containing phases of brushite, monetite, and newberyite, with different dissolution rates. Multiphase ceramics leads to volumetric resorption with preservation of their geometric shape, which was confirmed by the results of an evaluation of the output of magnesium Mg²⁺ and calcium Ca²⁺ ions into the contact solution of the ceramics and the X-ray density of ceramic samples during subcutaneous implantation. The combined introduction of sodium pyrophosphate decahydrate and citric acid monohydrate as setting inhibitors neutralizes their insignificant negative effect on the physico-chemical properties of ceramics (strength, pH, porosity), determining the optimal composition. In vivo experiments with setting inhibitors in the composition of ceramics showed a different biological response, affecting the rate of resorption on par with magnesium ions. Preliminary data on biocompatibility and solubility determined magnesium-calcium phosphate ceramics containing additives that regulate setting to be a potential material for bone tissue restoration and a vector for further research, including in orthotopic implantation models.

Biocompatibility of ceramic materials in Ca₂P₂O₇-Ca(PO₃)₂ system was investigated using different methods, including in vitro and in vivo tests. Ceramic materials in the Ca₂P₂O₇-Ca(PO₃)₂ system were obtained by annealing cement-salt stone based on powder mixtures of calcium citrate tet-rahydrate Ca₃(C₆H₅O₇)₂·4H₂O and monocalcium phosphate monohydrate (MCPM) Ca(H₂PO₄)₂·H₂O. The phase composition of cement-salt stone included brushite, monetite as a result of chemical reaction of starting components after adding of water. The presence of citric acid as by-product of chemical reaction, leads to increase the setting time of the cement-salt stone. Highly concentrated aqueous suspensions based on calcium citrate and MCPM powders providing content of calcium polyphosphate Ca(PO₃)₂ up to 20 wt % in ceramics were used for designing bioresorbable materials. The presence of an excess of monocalcium phosphate monohydrate makes it possible to reduce the annealing temperature of ceramics, which is associated with the formation of a lower melting phase of Ca(PO₃)₂. In vivo tests shown that obtained ceramic materials can be recommended for regenerative treatments for bone defects.

Despite a long period of application of metal implants, carbon–carbon medical composites are also widely used for bone defect prosthesis in surgery, dentistry, and oncology. Such implants might demonstrate excellent mechanical properties, but their biocompatibility and integration efficiency into the host should be improved. As a method of enhancing, the electrophoretic deposition of fine-dispersed hydroxyapatite (HAp) on porous carbon substrates might be recommended. With electron microscopy, energy dispersion X-ray and Raman spectroscopy, and X-ray diffraction, we found that the deposition and subsequent heat post-treatment (up to the temperature of 400 °C for 1 h) did not lead to any significant phase and chemical transformations of raw non-stoichometric HAp. The Ca/P ratio was ≈1.51 in the coatings. Their non-toxicity, cyto- and biocompatibility were confirmed by in vitro and in vivo studies and no adverse reactions and side effects had been detected in the test. The proposed coating and subsequent heat treatment procedures provided improved biological responses in terms of resorption and biocompatibility had been confirmed by histological, magnetic resonance and X-ray tomographic ex vivo studies on the resected implant-containing biopsy samples from the BDF1 mouse model. The obtained results are expected to be useful for modern medical material science and clinical applications.