[Experimental design of the lower jaw functional loading for implant-supported restoration in unfavorable clinical conditions]. / Eksperimental'noe modelirovanie funktsional'noi nagruzki nizhnei chelyusti pri protezirovanii s oporoi na implantaty v neblagopriyatnykh klinicheskikh usloviyakh.

THE AIM OF THE STUDY: Was to create a finite element design to evaluate the masticatory stress distribution on the full fixed prosthesis with three supporting implants and the mandibular bone in the conditions most closely resembling the real ones. MATERIALS AND METHODS: The geometric design was created with the results of a CBCT of a real patient. The transfer of the DICOM into STL format was carried out in the Mimics Medical 21 program, in which the author's splinting device for the implant was designed. The actual thicknesses of the patient's compact and cancellous bone layers were measured with Romexis ver. 4.5.1. Scanning of the artificial dentition was performed with the iTero Element 2 Version 1.7 which created an object in STL format. Design was performed in the package for finite element analysis Ansys 19.3. Tetrahedral elements of the second order were used for calculation. The structural elements were connected in the model by a rigid «Bonded¼ contact. RESULTS: A finite element model has been created for the experimental load design on the lower jaw for immediate implant restoration with few supports in combination with a device for stabilizing the implant in unfavorable clinical conditions. It is shown that the designed finite element model takes into account the biomechanics of the prosthesis with few supports. When calculating, the entire model was fixed to the mandibular process at its base, and was loaded with a force of 500 N, distributed over the teeth. The values of the maximum stresses obtained in the elements were 51.8 MPa for the compact layer and 245 MPa for titanium elements. CONCLUSION: Thus, we created personalized geometric and finite element models for calculating the distribution of functional load on a long full fixed implant-supported prosthesis with few artificial supports, which makes the experimental results more accurate and correct.

[A comparative analysis of reproducibility of the jaws centric relation determined with the use of digital technologies]. / Sravnitel'nyi analiz vosproizvodimosti tsentral'nogo sootnosheniia cheliustei s ispol'zovaniem tsifrovykh tekhnologii.

AIM: To compare the precision of centric relation (CR) assessment by various methods using digital technologies. MATERIAL AND METHODS: Determination of the CR was carried out in the clinic of prosthetic dentistry on patients with intact dentition using methods of bilateral manipulation, anterior jig, leaf gauge and device for intraoral recording of the gothic arch angle. Optical jaw impressions were obtained using the intraoral 3D scanner Trios (3Shape) and the CR registers were scanned using the laboratory scanner Prime (DOF). To evaluate the reproducibility of the CR, the computer program of 3D modeling Avantis (Russia) was used, which integrated the obtained optical impressions and digital copies of the CR registers. RESULTS: None of the methods showed 100% accuracy in CR assessment. The most stable reproducibility of the position of the mandible in the CR relative to the first registration was determined by the method using an anterior jig (of our own design) and amounted to 0.119±0.012 mm, which is significantly less than using the methods of bilateral manipulation (0.225±0.028, p≤0.05) and a leaf gauge (0.207±0.02, p≤0.05). We observed a similar mean values of the reproduction accuracy when determining the CR by recording the Gothic arch angle (0,120±0,013, p≤0.05), which also has a significantly lower value (p≤0.05) compared to other methods for CR determining.

[The reasons for complications in the use of metal-ceramic dentures]. / Prichiny oslozhnenii pri primenenii metallokeramicheskikh protezov.

A total of 262 patients aged 32 to 58 were examined and 246 patients aged 30 to 60 were treated. Of the 944 cermet crowns examined complications were found in 88 (9.34%). Ceramic fractures occurred in 20 crowns, inflammatory processes in the gingiva developed in 22 cases, functional overexercise of the periodontium in 21, failure of cement fixation in 18, apical periodontitis in 7 cases. The causes of these complications are analyzed and measures to prevent them worked out. If all preventive measures were adhered to in the treatment of 246 patients fitted with dentures, complications occurred three times more seldom (in only 3.14% of cases).

[The preparation of the maxillodental system before using using metal-ceramic dentures]. / Podgotovka zubocheliustnoi sistemy pered primeneniem metallokeramicheskikh protezov.

Orthodontic treatment using cermet dentures was carried out in 496 patients aged 26 to 60. Therapeutic surgical and orthodontic treatment of the maxillodental system was carried out before denture fixation. Late results in periods from 1 to 5 years were followed up in 396 patients. No complications were observed in 384 (96.9%). Only 12 patients developed complications: porcelain fracture in 4, periodontal inflammations in 5, and a partial relapse of occlusion reduction and distal dislocation of the mandible in 3.

[The use of metal ceramic dentures in deformities of the dental arches]. / Primenenie metallokeramicheskikh protezov pri deformatsiiakh zubnykh riadov.

A total of 167 patients aged 26 to 59 were fitted with cermet dentures. Before denture making the maxillodental system of the patients was prepared to it. Orthodontic treatment aimed at dentoalveolar shortening was found effective only in young (up to 35-40) patients with intact periodontium. In older patients the protruding teeth were shortened after pulp removal. If anterior teeth were inclined by more than 10 degrees, their pulp was eliminated, and cast dowel insertions were made, changing the inclination axis, and a cover construction shaped as cermet dentures. Good late results were attained in 95.9% of patients.

[Orthodontic treatment in the distal displacement of the mandible]. / Ortopedicheskoe lechenie pri distal'nom smeshchenii nizhnei cheliusti.

A total of 598 patients with various occlusions and dentition defects were examined; 112 (18.7%) of these presented with distal dislocation of the mandible. Shortening of interalveolar distance was found to play an important role in the pathogenesis of this dislocation. This shortening occurs in abnormal teeth abrasion and loss of many molars and premolars maintaining the occlusion height. Masticatory function was found disordered in 56 (50% of patients with distal dislocation of the mandible. Orthodontic treatment of these patients was carried out by sagittal shift of the mandible to a distance of 1 to 2 mm and subsequent fitting with prostheses. Good results were attained in 94.55% of cases.