ИСТИНА

The most important properties of materials for bone implantation are biocompatibility, resorbability and osteoconductivity. Calcium phosphates with the Ca/P ratio less than 1,67 are biocompatible due to the similarity of native bone tissue, and their resorption ability increases with a decrease in this ratio; therefore, calcium phosphates with the ratio of 0,5≤Ca/P≤1 are especially promising. Creation of porous ceramic materials with good osteoconductive properties (high penetration, porosity) is possible by means of additive manufacturing (3D printing). Stereolithography is one of the most universal and perspective methods, in which 3Dobject is created using photopolymerization of special suspensions. In order to obtain ceramic material, it is necessary to use suspensions containing powder of the demanded phase composition and a lightcured monomer. However, the printing quality of such suspensions with ordinary white inorganic powders is very poor due to the light scattering at the powder particles. Addition of colorants allows increase in the printing resolution; however, calcium phosphates obtained by heat treatment (T < 900oC) of amorphous calcium phosphate synthesized from solutions of phosphoric acid and calcium acetate, are inherently grey due to the presence of residual carbon. In this study the method of amorphous hydrated calcium phosphates synthesis using ion exchange was elaborated. The properties of the stereolithographic suspensions (viscosity, photosensitivity, and critical energy of polymerization) were explored. It was shown that the variation of the photosensitivity of suspensions by changing the colour of powder could sufficiently improve the resolution of stereolithographic printing. Ceramic materials with high osteoconductive properties (with the architecture of gyroid) were obtained using stereolithographic printing. Created porous ceramics based on calcium poly and pyrophosphates exhibit good resorbability and osteoconductivity and are suitable for medical applications. The authors would like to thank the Russian Science Foundation (Grant No. 151900103) for providing financial support to this project