Materials based on Mg²⁺-containing phosphates are gaining great relevance in the field of bone tissue repair via regenerative medicine methods. Magnesium ions, together with condensed phosphate ions, play substantial roles in the process of bone remodeling, affecting the early stage of bone regeneration through active participation in the process of osteosynthesis. In this paper we provide a comprehensive overview of the usage of biomaterials based on magnesium phosphate and magnesium calcium phosphate in bone reconstruction. We consider the role of magnesium ions in angiogenesis, which is an important process associated with osteogenesis. Finally, we summarize the biological properties of calcium magnesium phosphates for regeneration of bone.

Materials based on Mg2+-containing phosphates are gaining great relevance in the field of bone tissue repair via regenerative medicine methods. Magnesium ions, together with condensed phosphate ions, play a significant role in the process of bone remodeling, affecting the early stage of bone regeneration through active participation in the process of osteosynthesis. Here we pro-vide a comprehensive overview of the usage of biomaterials based on magnesium phosphate and magnesium calcium phosphate in bone reconstruction. The role of magnesium ions in angiogene-sis, an important process associated with osteogenesis, is considered. Finally, the biological properties of magnesium phosphates for bone regeneration are summarized. They show promis-ing results in terms of use as bone replacement material.

Synthesis from mixed-anionic aqueous solutions is a novel approach to obtain active powders for bioceramics production in the CaO-SiO₂-P₂O₅-Na₂O system. In this work, powders were prepared using precipitation from aqueous solutions of the following precursors: Ca(NO₃)₂ and Na₂HPO₄ (CaP); Ca(NO₃)₂ and Na₂SiO₃ (CaSi); and Ca(NO₃)₂, Na₂HPO₄ and Na₂SiO₃ (CaPSi). Phase composition of the CaP powder included brushite CaHPO₄‧2H₂O and the CaSi powder included calcium silicate hydrate. Phase composition of the CaPSi powder consisted of the amorphous phase (presumably containing hydrated quasi-amorphous calcium phosphate and calcium silicate phase). All synthesized powders contained NaNO₃ as a by-product. The total weight loss after heating up to 1000 °C for the CaP sample—28.3%, for the CaSi sample—38.8% and for the CaPSi sample was 29%. Phase composition of the ceramic samples after the heat treatment at 1000 °C based on the CaP powder contained β-NaCaPO₄ and β-Ca₂P₂O₇, the ceramic samples based on the CaSi powder contained α-CaSiO₃ and Na₂Ca₂Si₂O₇, while the ceramics obtained from the CaPSi powder contained sodium rhenanite β-NaCaPO₄, wollastonite α-CaSiO₃ and Na₃Ca₆(PO₄)₅. The densest ceramic sample was obtained in CaO-SiO₂-P₂O₅-Na₂O system at 900 °C from the CaP powder (ρ = 2.53 g/cm³), while the other samples had densities of 0.93 g/cm³ (CaSi) and 1.22 (CaPSi) at the same temperature. The ceramics prepared in this system contain biocompatible and bioresorbable phases, and can be recommended for use in medicine for bone-defect treatment.

Amorphous calcium phosphate powders stabilized by crystallization inhibitors based on carboxylate and phosphate salts have been obtained by precipitation from solutions at 10 and 25°C. The presence of inhibitors leads to dispersed precipitates especially for samples with \({{{\text{P}}}_{{\text{3}}}}{\text{O}}_{9}^{{3 - }}\) and \({{{\text{P}}}_{{\text{3}}}}{\text{O}}_{{10}}^{{5 - }}\) (the size of primary agglomerates is 300–400 nm); the high values of ζ potential for particles in \({{{\text{P}}}_{{\text{2}}}}{\text{O}}_{7}^{{4 - }}{\text{,}}\) \({{{\text{P}}}_{{\text{3}}}}{\text{O}}_{9}^{{3 - }}\), and \({{{\text{P}}}_{{\text{3}}}}{\text{O}}_{{10}}^{{5 - }}\) suspensions (<–20 mV) indicate the sufficient aggregative stability of such suspensions. Practical interest in the context of the use of amorphous phosphate powders for production of bioceramics and composites by stereolithographic 3D printing is attracted to phosphates obtained in the presence of trimeta- and tripolyphosphates, inhibitors studied in this work for the first time.

Powder mixtures of MgSO₄ with 5–20 mol.% Na₂SO₄ or K₂SO₄ were used as precursors for making water-soluble ceramic molds to create thermoplastic polymer/calcium phosphate composites by low pressure injection molding. To increase the strength of the ceramic molds, 5 wt.% of tetragonal ZrO₂ (Y₂O₃-stabilized) was added to the precursor powders. A uniform distribution of ZrO₂ particles was obtained. The average grain size for Na-containing ceramics ranged from 3.5 ± 0.8 µm for MgSO₄/Na₂SO₄ = 91/9% to 4.8 ± 1.1 µm for MgSO₄/Na₂SO₄ = 83/17%. For K-containing ceramics, the values were 3.5 ± 0.8 µm for all of the samples. The addition of ZrO₂ made a significant contribution to the strength of ceramics: for the MgSO₄/Na₂SO₄ = 83/17% sample, the compressive strength increased by 49% (up to 6.7 ± 1.3 MPa), and for the stronger MgSO₄/K₂SO₄ = 83/17% by 39% (up to 8.4 ± 0.6 MPa). The average dissolution time of the ceramic molds in water did not exceed 25 min.