THE POSSIBILITY OF CLINICAL USE OF FIXED ORTHOPEDIC STRUCTURES MADE OF SINTERED ZIRCONIUM DIOXIDE AFTER THEIR TREATMENT WITH VARIOUS TYPES OF DIAMOND TOOLS (IN VITRO STUDY)
Introduction. Zirconium dioxide has a high mechanical resistance and it is completely biocompatible. The development of CAD/CAM technology has made possible the clinical use of zirconium dioxide structures in dentistry. But, all of the above physical and mechanical properties of zirconium dioxide determine the features of its mechanical processing in clinical dental practice, if it is necessary to carry out manipulations directly in the oral cavity. The research purpose was to determine the nature of the mechanical impact on the structure of samples made of ceramides based on zirconium dioxide when it is processed with various diamond tools, and to assess the suitability of tools with different methods of fixing the abrasive with multiple applications for further use. Material and methods. The material of the study is samples based on metastable tetragonal zirconium dioxide manufactured in a dental laboratory and standardized in thickness (1 mm). The influence of mechanical stresses on the structure and properties of the source material was evaluated by perforating the sample with diamond bores containing a special abrasive for processing zirconium. Bores with different types of abrasive fixation were studied: № 1 - diamond boron with synthetic abrasive fixed by ERA type; № 2 - diamond boron with composite fixing of imported abrasive; № 3 - edematous diamond boron with applying and fixing the abrasive by electroplating. Scanning electron microscopy was used to obtain images of the results of mechanical action of boron on samples of zirconium dioxide with a single and five - fold use of boron. We investigated the structure of the diamond tool itself for its suitability for further use. Results and discussion. Even with a single use, only solid - sintered burs completely retain the microstructure of zirconium dioxide, which allows further work with samples using the adhesive technique. Burs with a composite abrasive attachment cause partial destruction of the crystal lattice of zirconium dioxide with the possibility of using an orthopedic construction in the form of a temporary prosthesis. Electroforming burs completely destroy the crystal lattice and structure of the zirconium dioxide sample.