Mikhail Murashov

The relevance of the topic is determined by the need to improve the regulatory framework for organizing dental care, taking into account international experience and modern requirements for the quality, safety, and efficiency of medical services. In the context of active integration of national healthcare systems and the expansion of international cooperation, the comparative study of approaches to the regulation of medical activities acquires special importance. The use of a comparative approach makes it possible to identify patterns in the formation of legal norms, analyze the strengths and weaknesses of different management models, and assess their adaptability to epidemiological challenges, technological innovations, and the dynamically changing needs of the population. Materials and Methods. The study used the comparative legal method applied to the analysis of key regulatory documents governing the organization of dental care in Russia and China. The materials analyzed included Orders of the Ministry of Health of the Russian Federation No. 786n of July 31, 2020 “On the approval of the procedure for providing medical care to the adult population for dental diseases,” and No. 83n of February 10, 2016 “On the approval of disinfection procedures,” as well as certain provisions of the sanitary rules (SanPiN). The Chinese sources included the Basic Standards for Clinics (2022), the WS/T 842-2024 Infection Management Standard, and the T/CHSA-023-2023 Guideline. This methodological approach ensured an objective assessment of the structural and functional similarities and differences between the regulatory systems. The analysis revealed differences in the degree of formalization, level of detail, and regulatory priorities. The Russian system is characterized by strict standardization and detailed staffing regulations, which ensure manageability and stability. The Chinese model focuses on infection prevention, sanitary control, and flexibility in the implementation of requirements. The obtained results make it possible to outline directions for harmonization and identify opportunities for the mutual adoption of effective regulatory practices.

Subject. Currently, in prosthetic dentistry, significant attention is being paid to digital protocols. The conventional method of fabricating dental prostheses involves using silicone impression materials to obtain a working cast – a replica that closely mimics the spatial position of implants within the jawbone. The accuracy of this cast is a critical factor influencing the outcomes of prosthetic treatment. When performing implant-supported prosthetics, clinicians employ well-documented protocols using either open-tray or closed-tray impression techniques. Numerous scientific studies have compared the accuracy of conventional impressions to that of digital impressions. However, a comparative analysis of conventional impressions made with open-tray, closed-tray techniques and digital impressions has not been found in the literature. Therefore, conducting this comparative study represents a relevant and timely research objective. Objectives. A comparative analysis of implant-level impression techniques for single implant-supported crowns with the aim of minimizing prosthetic misfit and providing clinical recommendations. Materials and methods. A reference model fabricated via additive manufacturing from an STL file acquired through an intraoral scan of the patient served as the control. Conventional impressions were made using a polyvinyl siloxane material, while digital impressions were acquired with a 3Shape TRIOS intraoral scanner. Results. The smallest deviation from the reference model in the centro-occlusal (CO) and axio-occlusal (AO) zones was observed for the digital impression technique (17.5 ± 0.7 µm and 50.8 ± 2.4 µm, respectively), followed by the open-tray technique (28.5 ± 1.9 µm and 58.0 ± 1.3 µm, respectively). The closed-tray technique demonstrated the lowest accuracy (101.8 ± 6.3 µm and 99.0 ± 1.7 µm, respectively). Regarding the medio-axial (MA) zone, the most accurate results were obtained with the closed-tray and open-tray techniques (8.5 ± 0.7 µm and 31.8 ± 0.9 µm, respectively), while the digital impression method yielded the least accurate result (63.3 ± 3.0 µm). Conclusions. In conclusion, we would like to say that for taking precise impression from a single implant, it’s recommended to use a digital protocol and digital impression. For taking a conventional silicon impression, the open-tray technique showed the best results, being more accurate in compare the closed-tray technique.

Subject. SLA and LCD 3D-printing technologies used in dentistry and maxillofacial prosthetics. Objectives. To compare and systematize SLA and LCD 3D printing devices and technologies available in the Russian Federation. To Print a prototype of the ear epithesis. Methodology. collection and analysis of available literature sources, systematization of the information received. Comparison of various 3D printers, recommendations for usage depending on the required tasks. 3D-Print of epithesis of the ear by using LCD technology. Results. SLA and LCD printing technologies are similar in a number of parameters we studied. LCD technology showed higher printing speed compared to SLA technology. At the same time, the accuracy of the product for all SLA printers turned out to be higher in comparison with the most accurate LCD technology printer. The cost of SLA printers is on average higher than LCD printers. The prototype of the epithesis of the auricle can be reproduced using LCD technology. Conclusion. Photopolymer 3D printers with SLA technology produce more detailed and sharper end products than LCD printers. Photopolymer 3D printers with SLA technology are slower than LCD technology. SLA and LCD technologies are quite close in certain parameters. LCD technology can be used at the stages of rehabilitation of patients with ear defects.

BACKGROUND: Immediate implant placement and immediate loading after maxillary central incisor extraction are of great importance. Implant placement with immediate loading is the most preferred method of treatment in the long term. The anatomical constrictions of the maxilla make implant placement difficult. To achieve primary stability and make a screw-retained crown, dental surgeons are forced to fix the implant placing it toward the palatal wall. When the implant is placed this way, the crown will be bulkier than the one of the extracted tooth. This change in anatomy can lead to patient discomfort and some parafunctions (in speech, chewing, etc.). AIM: To assess the potential discomfort in patients with changes in the crown anatomy of maxillary central incisors after implant-supported prosthetics. METHODS: Fifty students (25 men and 25 women) underwent intraoral scanning with the 3Shape scanner. A possible increase in the crown volume was simulated in ExoCAD at a rate of an implant + titanium base + layer of structural material with zirconium dioxide as an example, on average equal to 34 mm. Onlays imitating the increased crown volume were milled and fixed in the oral cavity of the participants on tooth 1.1, and further examinations were conducted. RESULTS: The examination revealed that the crown anatomy change brought some discomforts in most of the respondents whose speech and eating were affected. CONCLUSION: The results reveal that a change in the anatomical shape of the crown during implant-supported prosthetics can affect vital functions and cause discomfort. More attention is needed to implant placement planning, taking into account further prosthetics in the esthetic area. Therefore, the use of angulated implants is encouraged.

Background: Success of immediate implant placement in the area of maxillary central incisor greatly depends on the degree of tightening of the fixing screw of the fully zirconia crowns. For treatment of this kind, clinicians use implants of various designs and implants with angled abutments to bypass anatomical limitations, achieve primary implant stability, and fabricate a screw-retained crown. However, the crown fabricated for the implant placed can experience non-axial loads during occlusion, which can lead to screw loosening and adversely affect treatment success, especially in the early post-operative period. Objective: to perform a comparative analysis of the effect of cyclic loading on the reliability of the fixing screw in full zirconia crowns supported by angled implants with platform inclination of 12, 24, 36, by straight implants and straight implants with angled abutments. Materials and methods: the degree of the prosthetic screw tightening was studied in 30 samples, 6 groups of 5 implants (straight implants, straight implants with standard 17 angled abutments and 12 custom abutments, angled implants with platform inclination of 12, 24, and 36. A full zirconia crown of maxillary central incisor was fabricated and fixed on every implant and subsequently exposed to cyclic loading up to 1*106 cycles. Afterwards, the maximum unscrewing torque was determined for each group. Statistical analysis was carried out. Results: the minimum values of the maximum torque were 20.8040.01 N/cm for the group of straight implants with 17 angled abutments, and the maximum values for the group of straight implants were 22.820.04 N/cm. There was no significant difference in values between the straight and angled implant groups. However, the values in these groups were higher compared to the groups of implants with angled abutments. Conclusion: the study showed that fixing screws are more reliable in crowns supported by straight implants and angled implants with different platform inclinations. Therefore, these implants are the most preferred option for immediate implant placement in the anterior region.

BACKGROUND: Immediate implant placement to the fresh socket of the extracted tooth, with immediate loading, is well documented. Dental roots in proximity to the vestibular plate require thorough attention from clinicians. Implants placed close to the vestibular plate often lead to its resorption and gingival recession. Therefore, dental surgeons place implants 23 mm away from the vestibular plate. In turn, prosthodontists plan implant placement so that the screw channel is not on the vestibular surface, which is most significant in the aesthetic area. However, this is not always possible, and there is a conflict between implant placement with proper primary stability and its simultaneous loading with a screw-retained crown. AIM: To conduct radiological assessment of the ideal implant placement for a screw-retained crown. MATERIALS AND METHODS: A total of 120 cone-beam computed tomography (CBCT; 3 groups of 40 people with different root positions) were analyzed. In each group, the possibility of extracting tooth 1.1 and inserting an implant was evaluated in compliance with the protocol for immediate implantation and the possibility to have the screw shaft of the artificial crown on the palatal surface. RESULTS: Group C was defined as the most favorable for immediate implant placement with a screw-retained crown. The least favorable was group N. In total, the screw channel in 40% of the cases was located palatally, 26.6% to the incisal edge, and 33.3% on the vestibular surface. CONCLUSIONS: Careful analysis of CBCT when planning implant-supported restoration in the aesthetic area is an integral part of the treatment. A team approach is required from surgeons and prosthodontists when planning. In a larger percentage of cases, implant-supported prosthetics in the maxillary central incisors involve the use of alternative solutions for the restoration of screw-retained crowns.