PERSONALIZED CHOICE OF STRUCTURAL MATERIALS FOR ARTIFICIAL CROWNS FROM THE LEVEL OF MULTI-UNIT ABUTMENT OR TITANIUM PLATFORM FOR DIRECT PROSTHETICS ON DENTAL IMPLANTS

The high prevalence of secondary adentia in the adult population, as well as increased aesthetic requirements of patients has contributed to the development of orthopedic dentistry. Direct prosthetics on dental implants have been increasingly used for replacing defects in the dentition. However, the choice of structural materials for dental implant-supported prostheses is not fully understood. Hence, it remains a debatable issue. Purpose of the study: to justify the optimal structural materials for artificial crowns from the level of a multi-unit abutment or a standard titanium platform for direct prosthetics on dental implants with the use of finite-element analysis of the stress-strain state of the “bone tissue-dental implant-abutment-suprastructure” multidimensional model under the conditions of simulation modeling. Materials and methods. Specialized CAD / CAE software was employed to develop multidimensional computer models of biomechanical systems such as “bone tissue-dental implant-abutmentsuprastructure” with simulation of direct prostheses on dental implants with the corresponding physical and mechanical properties of structural elements and load conditions. The created 10 simulation models were based on combinations of two types of abutment (standard titanium platform (A1) and multi-unit abutment (A2)), and five structural materials of the crown, including lithium disilicate glass ceramic (KM1), polymer-infiltrated hybrid ceramic (KM2), polymethyl methacrylate (PMMA) (KM3), zirconia (KM4), and multi-layer zirconia (KM5)). The stress-strain state and the bearing capacity of biomechanical systems were assessed with the use of the von Mises stresses analysis and safety factors. Results. During a numerical experiment, there was revealed a complex stress-strain state in “bone tissue - dental implant - abutment - suprastructure” biomechanical systems. The maximum loads were recorded in systems with A1 and A2 type of abutment in the crown models (149.37 MPa and 142.08 MPa, respectively), spongy (4.25 MPa and 4.08 MPa) and the cortical bone (20.58 MPa and 20.61 MPa). The nature of the distribution of the von Mises stresses in the structural elements of systems with A1 and A2 types of abutments was found to be similar for all models under consideration with KM1, KM2, KM4, KM5 structural materials of crowns, except for the system with KM3 suprastructure material. Conclusions. Based on the findings of computer simulation of the stress-strain state of “bone tissue - dental implant - abutment - suprastructure” biomechanical systems, there have been grounded the optimal structural materials for dental implant-supported crowns for direct prosthetics by such abutment as a standard titanium platform and multi-unit abutment. The obtained values of the von Mises stresses analysis and safety factors showed that with external force applied to the dental implantsupported crown the at an angle of 11.5°, the greatest bearing capacity was ensured by biomechanical systems with a standard titanium platform and multi-unit abut- 45 «Art of Medicine» ISSN 2521-1455 (Print) ISSN 2523-4250 (Online) 4 (16) жовтень-грудень, 2020 ment with crown materials including zirconia (safety factors 6.22 and 6.42 respectively), multilayer zirconia (safety factors 5.52 and 5.70) and lithium disilicate glass ceramic (safety factors 2.39 and 2.52).