MONITORING OF CHANGES IN PHYSICOCHEMICAL AND CLINICAL CHARACTERISTICS OF THE DENTAL POLYMER MATERIALS USED IN ADDITIVE MANUFACTURING OF DENTAL PROSTHESES

The use of additive technologies in dentistry is a promising trend; however, the physical and mechanical properties of the materials intended for the fabrication of long-term fixed restorations remain understudied. The aim of this research is to determine the feasibility of the use of long-term fixed provisional restorations made of polymer materials, fabricated using 3D printing. The conformance of the physical and mechanical properties of NextDent C&B Micro Filled Hybrid (ND) and Detax Freeprint temp UV (DX) materials to ISO 1567:1999 standard, stability of their physical and mechanical properties under the conditions of accelerated aging, as well as their resistance to the oral cavity environment were studied. As a result of the performed studies, the DX material turned out to be superior to ND with respect to most characteristics. Clinical observations were conducted on the treatment of chronic generalized periodontitis using the following fixed provisional splints made of various materials: DX, fabricated according to the Slide-And-Separate technology, splints fabricated using the CAD/CAM technology, and adhesive splints reinforced with a GlasSpan fiberglass thread. As a result of the analysis of the OHI-S and PI indices values, the absence of any statistically significant difference between the above-describe treatment methods was determined. The studied materials conform to the requirements of ISO 1567:1999; the materials exhibited different stability under the conditions of accelerated aging, nevertheless, they can be utilized for the fabrication of long-term fixed provisional restorations.

[COMPARATIVE EVALUATION OF THE DYNAMIC BIOMECHANICAL COMPATIBILITY OF SYNTHETIC VASCULAR PROSTHESES IN VITRO, EX VIVO AND IN VIVO]

Previously, the pattern of changes in the radial elasticity of the aortic wall in the longitudinal direction has been shown, which poses new challenges in the selection of the biomechanical properties of synthetic prostheses for replacing arterial vessels. The aim of the work was to develop a system of methods for assessing the biomechanical properties of vascular implants, allowing supplementing the known methods of testing on thromboresistance and healing. Samples of blood vessels prostheses were prepared using electrospinning technology with the polymer composition and the conditions of prosthesis formation so that their elastic properties in the physiological pressure range were as close as possible to the properties of native blood vessels. The following test methods were used: in vitro - elastometry on a universal testing machine under static and cyclic loading; ex vivo - tests on a hemodynamic test bench connected to the circulation of a pig; in vivo - implantation of vascular prostheses in a chronic experiment on pigs. The testing has shown a close correspondence of the elastic characteristics of the prostheses under static loading and tests on the hemodynamic bench was revealed. Under cyclic loading, a significant excess of the compliance of the prostheses on the hemodynamic bench was detected. In vivo tests in chronic experiments confirmed the results of testing on a hemodynamic bench. The results of the tests have shown that the synthetic prostheses manufactured by electrospinning technology, have a radial compliance of up to 15%. The proposed ex vivo test method makes it possible to obtain data that are necessary to optimize the requirements for the parameters of the manufactured prostheses matrices.