[Physical and mechanical properties of materials used in the technology of computer production of surgical templates]. / Fiziko-mekhanicheskie svoistva materialov, ispol'zuemykh v tekhnologii komp'yuternogo proizvodstva khirurgicheskikh shablonov.

OBJECTIVE: The physical and mechanical properties of samples printed from different materials subjected to post-processing in a clinic were evaluated. MATERIAL AND METHODS: Studied hardness and modulus of elasticity before and after sterilization by autoclaving. Based on the analysis of the literature and monitoring of the dental materials market, our choice fell on the most popular materials for 3D printing of surgical templates for dental implantation, such as: material 1 (FormLabs Dental SG Resin (Formlabs, USA)) and material 2 (NextDent SG (NextDent, Netherlands)). In connection with the events of recent years, we also took into the study a domestically produced polymer - material 3 (HARZLabs Yellow Clear PRO (HARZLabs, Russia)). RESULTS: As a result of the study, it was found that in each of the groups of materials studied, the values of the elastic modulus of sterilized samples are higher than the elastic modulus of samples that have not undergone sterilization. According to GOST 31572-2012 (ISO 1567:1999 Polymeric materials for denture bases, non-sterilized samples of group 2 are considered not to have passed the test, since all three samples of the studied group have a crack resistance index of less than 1 MN/m1.5. Crack resistance index of sterilized samples of the group of materials 2 is also close to 1. Samples of group 1 (both sterilized and non-sterilized) have the highest crack resistance. This group also has the highest flexural strength. On non-sterilized samples of material 1, there was no crack initiation along the cut and groove. The samples of other groups were mainly destroyed along the axis of the groove. CONCLUSION: Analyzing the obtained data and considering that all studies carried out were in accordance with dental standards, the researchers concluded that the increase in flexural strength after sterilization by autoclaving and the feasibility of using material 1 for the production of surgical templates in accordance with all manufacturer's recommendations.

[Modern methods of adhesive fixation of facial epitheses]. / Sovremennye metody adgezivnoi fiksatsii epitezov litsa.

This review presents an analysis of domestic and foreign literature on the issues of fixation of facial epitheses and combined maxillofacial prostheses, such as the use of craniofacial implants installed in the zygomatic bone, brow arches, orbital walls, mastoid process of the temporal bone with beam or magnetic beam fixation systems. The advantages and disadvantages of such fastening systems are described. The analysis and systematization of available data on medical adhesive compositions that can be used in maxillofacial prosthetics to hold facial epitheses has been carried out. Much attention is paid to the chemical composition of pressure-sensitive adhesives, water-based and silicone-based. Examples of such compositions are given. The physicochemical properties of medical adhesive systems that cause adhesive-cohesive interaction are described. This review presents the results of comparative studies to assess the fixing properties of various adhesives, as well as to study the formation of biofilm on the surfaces of prostheses and skin when using different adhesives.

[Clinical efficiency of occlusive splints in the treatment of patients with temporomandibular joint dysfunction complicated by bruxism]. / Klinicheskaya effektivnost' okklyuzionnykh shin v lechenii patsientov s disfunktsiei visochno-nizhnechelyustnogo sustava, oslozhnennoi bruksizmom.

OBJECTIVE: Improving the effectiveness of treatment of patients with temporomandibular joint (TMJ) dysfunction complicated by bruxism. MATERIAL AND METHODS: 70 patients with signs of parafunction of the masticatory muscles were selected for the clinical study. The patients were divided into 2 groups of 35 people. Splints were made for patients from the groups using 2 different 3D printing methods. The treatment was monitored using clinical and instrumental studies, electromyography of the muscles themselves and computed tomography of the TMJ after 3, 6 and 12 months. RESULTS: The severity of hypertonicity of the masticatory muscles decreased by the end of 3 months of treatment with the help of repositioning occlusal splints. After 6 months of treatment, the mean BEA decreased in both study groups, but to a lesser extent than in the first 3 months. After wearing a splint after 12 months, the decrease in muscle tone was insignificant. CONCLUSION: The clinical use of positioning splints plays a crucial role in the stabilization of occlusion and is a mandatory stage of complex treatment of patients with pathology of the occlusal-musculoskeletal complex.

[Manufacture of facial prosthesis by three-dimensional printing]. / Izgotovlenie litsevykh protezov metodom ob"emnoi pechati.

The objective of the literature review was to study and analyze literature sources on the methods and means of facial prosthesis manufacture by three-dimensional printing. MATERIALS AND METHODS: An analysis of information sources covering the last 15 years was carried out, in search sources as PubMed, Elsiver and eLIBRARY and on the website of the Federal Institute of Industrial Property. RESULTS: The technology of direct production of prostheses by volumetric printing from silicone materials is the object of research for its development. Most of the materials used for the manufacture of facial prostheses using 3D printing need technical improvements, often requiring expensive equipment, which in turn does not allow the method of manufacturing face prostheses by direct method in everyday clinical practice. CONCLUSION: Based on the obtained data there is a need to develop a new structural material for the manufacture of facial prostheses by 3D printing using laser stereolithography and digital LED projection technologies.

[Development of structural material for the manufacture of facial prosthesis by 3D printing]. / Razrabotka i otsenka fiziko-mekhanicheskikh svoistv konstruktsionnogo materiala, primenyaemogo v tekhnologii proizvodstva epitezov litsa metodom ob"emnoi pechati.

THE AIM OF THE STUDY: Was to develop and evaluate the physical and mechanical properties of a structural material for the manufacture of facial epithesis using photopolymer printing technology. MATERIALS AND METHODS: The study of the physical and mechanical properties of the developed structural material consisted of measuring the Shore hardness; determination of material strength at break, conditional yield strength, relative elongation at break and modulus of elasticity; the study of the characteristics described above, after artificial aging, simulating the daily use of a prosthesis. RESULTS: According to the test results, the samples of the studied material did not have a yield strength, they were torn at a deformation of 40-60%. The values of the conditional yield strength were 0.41±0.01 MPa, regardless of the time of the aging procedure. The values of the modulus of elasticity were 2.96±0.19 MPa and 2.88±0.14 MPa for the samples that underwent the aging procedure at 6 and 12 months, respectively. CONCLUSION: The results obtained were compared with the results of similar studies of structural materials used in 3D printing technology of facial prostheses, which allowed us to recommend the developed material for clinical use after evaluating its toxicological and biological characteristics.

[Evaluation of the clinical effectiveness of the use of a navigational surgical template in the vestibuloplasty protocol in patients with periodontal diseases]. / Otsenka klinicheskoi effektivnosti primeneniya navigatsionnogo khirurgicheskogo shablona v protokole vestibuloplastiki u patsientov s boleznyami parodonta.

THE AIM OF THE STUDY: Was to evaluate the clinical effectiveness of the use of a navigational surgical template in the vestibuloplasty protocol in patients with periodontal diseases. MATERIALS AND METHODS: There were 48 people selected to participate in the study and randomly divided into 2 equal groups. The patients of the main group underwent vestibuloplasty procedure using a free gingival graft modeled using the developed protocol and a navigational surgical template. Patients in the control group underwent a similar operation using classical technology. The study assessed postoperative pain, the index of early wound healing, Doppler fluometry of the transplanted flap and flap morphometric measurements. RESULTS: The results of all conducted studies confirmed the effectiveness of the developed clinical protocol. CONCLUSION: According to objective and subjective assessments, the use of a surgical navigation template can reduce the time and invasiveness of vestibuloplasty surgery, make it more comfortable for the patient and get a more predictable clinical result.

[Clinical efficacy of hydroxyapatite and tricalcium phosphate modified with hyaluronic acid in the treatment of patients with periimplantitis]. / Klinicheskaya effektivnost' primeneniya gidroksiapatita i trikal'tsiifosfata, modifitsirovannykh gialuronovoi kislotoi v lechenii patsientov s periimplantitami.

THE AIM OF THE STUDY: Was to assess the effectiveness of the use of hydroxyapatite (HAP) and tricalcium phosphate (TCF) modified with hyaluronic acid in the treatment of patients with periimplantitis. MATERIALS AND METHODS: Clinical studies were conducted in 128 patients (44% male and 56% female) aged up to 55 years, who sought dental care with the main diagnosis of periimplant mucositis and periimplantitis. To compare the features of osseointegration of dental implants under bone remodeling three groups of patients were formed: one control and 2 main ones. In the control group the wound was managed under a blood clot, in the first main group HAP and TCF and in the second main group HAP and TCF modified with hyaluronic acid were used. X-ray examination was performed in various modes. Clinical assessment of implant stability in the operated area was carried out using subjective (percussion and palpation method) and objective method of frequency resonance analysis using the Osstell ISQ device calculating the stability coefficient of the dental implant (SCDI). RESULTS: 12 months after the periimplant zone remodeling procedure the bone resorption rates surrounding the implant were statistically significantly the lowest in the second main group (0.682±0.006 mm, p<0.001) compared with the values in the control and first main groups (1.626±0.022 and 1.025±0.034 mm, respectively). In the former groups bone resorption continued to progress during the observation period. In patients of the second main group, the average values of the SCDI for all study periods were 68.97±1.09 units which turned out to be the highest indicator and significantly differed from the values of other observation groups (p<0.05), which may be due to a tighter fit of the implants to the surface of the newly formed bone tissue. CONCLUSION: The results of the study 12 months after the periimplant zone remodeling operation procedure prove the efficacy of HAP and TCF modified with hyaluronic acid for the treatment of patients with periimplantitis.

[Digital protocol for comprehensive planning of dental treatment. Clinical case analysis]. / Tsifrovoi protokol kompleksnogo planirovaniya stomatologicheskogo lecheniya. Analiz klinicheskogo sluchaya.

The main goal of the research presented in the article was to increase the effectiveness of dental orthopedic rehabilitation of patients by developing and implementing a complex of digital planning of the initial stages of treatment, including diagnostic methods, modeling, and manufacturing of prototypes of dentures using modern computer technologies. Planning of diagnostics and treatment of a dental patient with the use of modern digital technologies was proposed to be divided into stages. A complex of digital planning of dental orthopedic treatment was formed, which is illustrated by clinical case analysis. The first stage is the planning of the rehabilitation stage, which includes the diagnosis of the patient's dental status and preparation for orthopedic treatment. The second stage is 2D virtual planning of dental rows in the smile area-includes 2D visualization in the form of mandatory use of dental digital photography protocols and 2D creation of a virtual image of a smile using digital two-dimensional planning programs. The third stage includes 3D-virtual planning (mock-up) of teeth in an aesthetically significant area-included digitalization of clinical data of patients, namely, CBCT, scanning of the dentition separately and in the bite, face scanning. The fourth stage is the computer production of prototype dentures, according to the 3D virtual functional and aesthetic layout, which includes the production of prototypes of dentures by the additive method of 3D printing. At this stage, recommendations are given for the production of prototypes of dentures by 3D printing directly-in a direct way and using a silicone key-not in a direct way, obtained from a printed model of the prototype of the patient's dentition.

[Clinical evaluation of the innovative concept of teeth saving]. / Klinicheskaia otsenka innovatsionnoi kontseptsii sokhraneniia zubov.

AIM: To evaluate the effectiveness of the innovative concept of dental medical technologies in patients with resected (amputated) roots of teeth with and without periodontal diseases. MATERIAL AND METHODS: Of the 516 examined patients with periapical destructive foci of infection of various genesis, 4 clinical groups of 24 people were randomly formed: (1) with a diagnosis of apical periodontitis of incisors, canines or premolars with individual milled transdental implants made of zirconium dioxide; (2) patients with a similar diagnosis and concomitant periodontitis of moderate severity with the same implants; (3) patients with periapical destructive process of molars without periodontitis with the same implants. Control group (4) included patients with similar diagnoses with resection of the root apex without implantation. Patients of the study groups were operated in accordance with the developed clinical protocols, including the manufacture and installation of individual transdental implants with fixation in the postoperative period, developed within the framework of tooth-preserving technologies of immobilizing structures. RESULTS: The reinforcement of teeth with resected roots with transdental implants together with immobilization of these teeth in the postoperative period restores the biomechanical characteristics of the tooth 2.7 times more effectively. However, there is a slight change in the mobility of the operated teeth in an earlier period (after 3 months), which is associated with the resorption of the bone-replacing agent used to fill the intraoperative defect and with the defective formation of bone tissue. The values of peritelomeric 6 months after the operation differ from the control by 1.4 units only.

Simultaneous determination of deuteron quadrupole coupling constants and rotational correlation times: the model case of hydrogen bonded ionic liquids.

We show that deuteron quadrupole coupling constants (DQCCs), and reorientational correlation times of molecular bonds N-D that are involved in hydrogen bonding, can be determined from NMR T1 relaxation time experiments simultaneously. For this purpose, we used trialkylammonium-based protic ionic liquids (PILs) as model compounds. They exhibit high viscosities and wide liquid ranges that allow measurements far beyond the extreme narrowing region (ω0τc ≪ 1). The T1 minima already occur at temperatures significantly above room temperature. We obtain reasonable DQCCs for the liquid phase if anisotropic motion is considered. The DQCCs are very small due to attractive Coulomb interaction between the cation and anion, which is further enhanced by hydrogen bonding. The DQCCs strongly depend on the interaction strength of the anion but are independent of the alkyl chain length of the trialkyl ammonium cations pointing to the exclusive cation-anion interaction along the hydrogen bond.

[Control of primary adhesion of microorganisms and formation of biofilms on stomatological materials used for transdental implantation in dental stabilizing operations.]

Transdental implantation is an effective way to restore the lost biomechanical properties of a resected or amputated tooth. The choice of structural materials for the implant is the most important stage of treatment, in relation to the adhesion of aggressive microbiota to them. To characterize the adhesion of microorganisms of periodontopathogenic and cariogenic groups in vitro to experimental samples of zirconium dioxide and titanium alloys using cultural and electronic microscopic methods of adhesion evaluation as the first stage of biofilm formation. Samples for the experiment were prepared in the form of a tablet of standard form, on which the test strains were applied in an amount of 106CFU/ml. After shaking the unattached cells with ultrasound, they were seeded into dense nutrient medium to determine their number. In total, 14 strains of perodontopathogenic and cariogenic groups (including 3 reference strains) were used in the experiment. Scanning electron microscopy was used to visualize the adhesion of microorganisms. The results of the adhesion test to titanium nickelide and zirconium dioxide showed a significant reduction in adhesion for all microorganism species. In all variants (with all strains) the adhesion values to titanium nickelide and zirconium dioxide were statistically significantly lower than when using samples from a traditional titanium alloy. In scanning electron microscopy, single cells of test strains of perodontopathogenic microorganisms were determined on zirconium dioxide samples, while a considerable number of cells and the initial phase of biofilm formation were observed on the compared structural materials. Zirconium dioxide can be considered as an optimal choice material for the manufacture of transdental implants, which, in terms of its technological characteristics and low adhesion characteristics of microbes, is superior to the traditionally used titanium alloys.

Defibrillation of soft porous metal-organic frameworks with electric fields.

Gas transport through metal-organic framework membranes (MOFs) was switched in situ by applying an external electric field (E-field). The switching of gas permeation upon E-field polarization could be explained by the structural transformation of the zeolitic imidazolate framework ZIF-8 into polymorphs with more rigid lattices. Permeation measurements under a direct-current E-field poling of 500 volts per millimeter showed reversibly controlled switching of the ZIF-8 into polar polymorphs, which was confirmed by x-ray diffraction and ab initio calculations. The stiffening of the lattice causes a reduction in gas transport through the membrane and sharpens the molecular sieving capability. Dielectric spectroscopy, polarization, and deuterium nuclear magnetic resonance studies revealed low-frequency resonances of ZIF-8 that we attribute to lattice flexibility and linker movement. Upon E-field polarization, we observed a defibrillation of the different lattice motions.

Short X-ray pulses from third-generation light sources.

High-brightness X-ray radiation produced by third-generation synchrotron light sources (TGLS) has been used for numerous time-resolved investigations in many different scientific fields. The typical time duration of X-ray pulses delivered by these large-scale machines is about 50-100 ps. A growing number of time-resolved studies would benefit from X-ray pulses with two or three orders of magnitude shorter duration. Here, techniques explored in the past for shorter X-ray pulse emission at TGLS are reviewed and the perspective towards the realisation of picosecond and sub-picosecond X-ray pulses are discussed.

Comparison of the dynamics of n-hexane in ZSM-5 and 5A zeolite structures.

The translational and rotational dynamics of n-hexane adsorbed in ZSM-5 and 5A zeolites has been studied by neutron scattering and deuterium solid-state NMR, at various temperatures. The dynamics of n-hexane is quite different in the two zeolites. In the ZSM-5 structure, the molecule sits in channel segments, the energy barrier between adjacent adsorption sites is small and fast anisotropic motions are observed. In the 5A zeolite, the molecule is adsorbed in alpha-cages; the barrier between adjacent cages is larger so that the molecule spends a longer time exploring the volume of an alpha-cage, leading to a more isotropic motion. The diffusion coefficient of the molecule is reduced by more than 4 orders of magnitude in 5A zeolite compared with ZSM-5.

Two-dimensional J-resolved 13C solid-state NMR analysis of the products of ethylene conversion on zeolite H-ZSM-5.

Two-dimensional (2D) J-resolved 13C NMR spectroscopy has been used to analyze the products of ethylene conversion inside the channels of zeolite H-ZSM-5 at 373 K. The observed 13C signals of aliphatic hydrocarbon fragments have been attributed to various CHn (n = 1-3) groups. Multiplicities and positions of these signals suggest that a mixture of branched and linear ethylene oligomers is formed inside zeolite H-ZSM-5.