Tupis I. Ionomer dental cements based on niobium-containing sol-gel glass powders

The dissertation is devoted to the solution of an actual problem – the study of the basics of the synthesis technology of new ionomer cements based on niobiumcontaining glass powders. In the process of research, the problems of obtaining high-quality and inexpensive glass ionomer cements were worked out. It was established that the main producers of GIC are Japan and the USA. The composition and production technologies of glass ionomer cements manufactured in Europe, Asia and the USA were analyzed. The main methods of obtaining glass for ionomer cements, in particular high-temperature and sol-gel, are considered. The dissertation describes in detail the high-temperature and sol-gel methods of obtaining glass containing niobium. Also, the features of introducing niobium into the composition of glass are described. The optimal parameters for the hydrolysis of ethyl silicate 40 were established and its structure was determined. The technology of obtaining glass by the sol-gel method has been developed. Modified glass compositions and methods of their production are proposed. Glass was obtained by high-temperature synthesis and a study of its properties, such as density, water resistance, thermal coefficient of linear expansion, was carried out. X-ray phase analysis of powders obtained by the method of sol-gel technology was carried out. The solvent for the hydrolysis of Niobium chloride is selected. Precursors for the introduction of oxides during the synthesis of glass powders by the sol-gel method have been prepared. A detailed description of the ionomer cement mixing process is presented. The polymer component of ionomer cements, namely unsaturated carboxylic acids, was studied. The composition of the polymer solvent and the ratio of acids in it were established. The influence of each unsaturated carboxylic and optically active tartaric acid on the properties of ionomer cement was studied. Grids of ionomer cement compositions have been developed. The ability of glass ionomer cement to interact with water and SBF solution was determined. A study of the influence of the composition of the GIC on the compressive strength limit was carried out. The surface structure of glass ionomer cement was studied by electron microscopy. Photomicrographs and diffractograms are described. The thermal coefficient of linear expansion of glass ionomer cement was determined and the results were compared with the values of TKLR of dentin, as a result of which it was established that the thermal coefficient of glass ionomer cement samples is within its values. It was experimentally established that the correct working time with the material is achieved both by evaluating the technological parameters of the composite and its strength as a result of hardening. Research data showed that the content of niobium oxide in the composition of glass improves its characteristics and the properties of glass ionomer cements. It was proved that the sol-gel method made it possible to obtain glass at significantly lower temperatures than the traditional high-temperature method. The obtained properties were compared with the values of the properties of the ISO 9917-1: 2021 standard, as a result of which it was established that this material can be used as a glass ionomer cement for various classes of use.