The preparation of dental glass-ceramic composites with controlled fraction of leucite crystals

This work is dealing with synthesis of leucite powder, which can be used for the preparation of dental glass- ceramic composites by subsequent thermal treatment. Newly developed procedure is based on preparation of dental raw material as a mixture of two separate compounds: the crystalline leucite powder prepared at rela- tively low temperature and a commercial matrix powder. Hydrothermal synthesis of tetragonal leucite particles (KAlSi 2 O 6 ) with the average size of about 3 μm was developed in our laboratory. The leucite dental raw material was prepared by mixing of 20 wt.% of synthetic tetragonal leucite with commercial matrix. Dental composites were prepared from the dental raw material by uniaxial pressing and fi ring up to 960°C. Dilatometric measurements confi rmed that the coeffi cient of thermal expansion increased by 32% when 20 wt.% of the tetragonal leucite was added into the basic matrix. In addi- tion, it was showed that the synthesized leucite powder was suitable for the preparation of leucite composites with controlled coeffi cient of thermal expansion. High value of the thermal expansion coeffi cient enables ap- plication of prepared composite in metal-ceramics restorations.