DETERMINATION OF CYCLIC FATIGUE OF A NICKEL-TITANIUM COXO SC PRO FILE USING A SIMULATION ENDODONTIC UNIT.

The use of nickel-titanium instruments during endodontic treatment ensures high-quality treatment of root canals. However, during instrumentation in the curved root canals of nickel-titanium instruments experience cyclic loading, which leads to their breakage. The splinter of the tool in the root canal makes it difficult for high-quality processing and obturation of the root canal, which is a very urgent problem. To carry out instrumental processing in canals with various anatomical and topographic features, the files must have phenomenal flexibility, lack of straightening of the canal, and have a safe non-aggressive tip. And for this reason, one of the most popular nickel-titanium COXO SC PRO tools was selected as a study, which, according to the manufacturer, have all the listed properties. The aim of the study is to determine the limit of resistance to cyclic loading and signs of breakage of the nickel-titanium endodontic instrument COXO SC PRO. Sterilization treatment, which is based on autoclaving, significantly reduces the strength characteristics of COXO SC PRO nickel-titanium files, which limits the use of these tools to one-time use without the risk of their breakage.

[Research on microflora and the qualitative composition of periodontal pathogens by PCR method in patients with root caries and external cervical resorption]. / Issledovanie mikroflory i opredelenie kachestvennogo sostava parodontopatogenov metodom PTsR u patsientov s kariesom tsementa i naruzhnoi tservikal'noi rezorbtsiei.

OBJECTIVE: The aim of the study was to study the microflora of periodontal pockets and gingival fluid; determine the qualitative composition of periodontal pathogens by PCR; to determine the main associations of microorganisms, to determine the periodontal index in patients with cement caries, external pathological resorption and in patients from the comparison group. MATERIAL AND METHODS: The examination included 80 patients, including 28 patients with a diagnosis of cement caries, 25 patients with a diagnosis of external cervical root resorption, 27 patients in the comparison group without tooth root damage. Based on the results of microbiological studies in various clinical conditions of the oral cavity, in particular, in different forms of lesions of the periodontium and hard tissues of teeth, the predominant microbial representatives and their combinations were identified. RESULTS: According to the study, it was revealed that all patients with cement caries and external pathological resorption have pathological processes arising in the periodontium. The study of the qualitative composition of the microflora showed that in patients with cement caries, the following associations of microorganisms are most often found: Aggregatibacter actinomycetemcomitans, Prevotella intermedia, Tannerella forsythia, Porphyromonas gingivalis, Candida albicans, Treponema denticola. Patients with external pathological resorption of microorganisms were found in patients with external pathological resorption of microorganisms: Prevotella intermedia, Treponema denticola, Candida albicans, Tannerella forsythia, Porphyromonas gingivalis, Epstein-Barr virus. These periodontal pathogenic microorganisms have a wide range of pathogenicity factors, which allows them to induce a prolonged inflammatory process. CONCLUSION: The study of the microflora of periodontal pockets and gingival sulcus in case of caries of cement and external pathological resorption is an important link in preventing the development and aggravation of pathological conditions of hard tissues of the tooth root and periodontal tissues.

[The need for specific toothpaste in patients receiving occlusal splint therapy]. / Neobkhodimost' podbora spetsial'noi zubnoi pasty u patsientov s okkliuzionnymi kappami.

The aim of the study is to determine the optimal properties of toothpaste for patients receiving occlusal splint therapy. The study comprised 50 people with full dentition (21 male and 29 female) divided into two groups. The main group included 25 individuals receiving occlusal splint therapy while 25 people who did not use splints were recruited as controls. Each group was further divided into two subgroups according to toothpaste used for regular oral hygiene. Examinations were performed after 14, 30 and 90 days using hygienic indices of NCI-C and Turesky and PMA gingival index. The combined effect of toothpaste was estimated by the change in the volume and acidity of saliva. The results suggest a better level of hygiene in the group I, which used toothpaste with sodium bicarbonate and silica.

[Periodontal diseases and complicated pregnancy]. / Bolezni parodonta i oslozhnennoe techenie beremennosti.

PURPOSE: Based on the datas available in the modern literature, to conduct a study on the effect of dental diseases on the course of pregnancy and outcome; mainly, the impact of periodontal disease on the low birth weight of the newborn and premature birth. MATERIAL AND METHODS: This article is based on the study of materials from foreign and domestic studies found in the databases Pubmed and Elibrary. Literature data were used for the last 15 years. RESULTS: The majority of pregnant women who are not receiving due dental examination and suffering with those or other diseases of the oral cavity have an unfavorable outcome of pregnancy, including premature births and low weight of the premature newborn. The role of the chronic effect of oral microorganisms Porphyromonas gingivalis (P. gingivalis) and Fusobacterium nudeatum, as well as local increase in prostaglandin E2 (PGE2) and tumor necrosis factor (TNF-α), in the implementation of the inflammatory reaction leading to a decrease in the weight of the fetus by 15-18%. CONCLUSION: Due to the conducted research it was established that periodontal diseases and other infectious diseases of the oral cavity negatively affect the course of pregnancy and its outcome. The main problems were the lack of women's health education in terms of preparing for pregnancy and sanitation of foci of infection in the oral cavity both before pregnancy and at the time, as well as poor access to the dentist and not receiving proper prevention and, if necessary, treatment of oral diseases.

[Xerostomia and means that facilitate its symptoms].

There are a number of reasons that lead to inadequate salivation or complete cessation of salivation. Among others, one of the main can be systemic diseases like Sjögren's syndrome, and the use of medication and radiation therapy. When affected by Xerostomia, oral mucosa requires constant moisturizing. Medicaments stimulating saliva secretion and moisturizers for oral mucosa alleviate symptoms in most of the cases. LABORATORIOS KIN S.A. is a Spanish company offering a mouth moisturizing products' line, among others, KIN HIDRAT toothpaste and KIN HIDRAT spray with a formulation close to natural saliva.

[Prevalence of dental diseases among Moscow students and need of dentistry].

A clinical epidemiologic study was made among 432 Moscow students and as a part of it was found the high prevalence rate of pathologies of dentition and variety of nosologic forms. The most common cases were: caries, periodontal disease, deformity and anomalies of tooth position. These findings were necessary to estimate the need of all types of dentistry for Moscow students. It was specified that 43% of students were in need of filling and dental restoration, 35% were in need of crowns of tooth, 22% were in need of dental restoration by means of orthopedic constructions. Endodontic dentistry was necessary for 31% of students, surgical removal - for 8%, periodontal dentistry - for 37%.

[Composite materials of different classes in practical dental surgery]. / Kompozitnye materialy razlichnykh klassov v praktike terapevticheskoi stomatologii.

Presents the indications for the use of autohardening composite materials in dentistry and validates the need in introduction of materials of different classes along with universal hybrid composites. Sums up the results of introduction of these materials into practice and discusses the trends in the practical use of photohardened composites in Russia.

[Heterologous epitopes in the central part of the hepatitis B virus core protein]. / Geterologichnye épitopy v tsentral'noi chasti core-belka virusa gepatita B.

A set of plasmids was constructed determining synthesis of hybrid proteins with insertions of antigenic determinants of preS1 and preS2 regions of HBV in the middle part of HBcAg. The polypeptides containing the 31-36 or monomeric 94-105 preS1 epitopes were water-soluble and formed particles similar to the 27-nm ones of native HBcAg, possessing antigenic properties of both HBcAg and the inserted epitope, while the hybrids containing 133-143 of preS2 or a trimeric form of the 94-105 preS1 epitope became membrane-bound. Another hybrid encoded by plasmid pPS2M31 contained two regions of HBcAg modification: insertion of amino acids 133-143 a.a. (preS2 region) in the N-terminal part and 31-36 (preS1) in the middle part of the carrier. The immunogenicity of the epitope inserted into the middle part of the HBcAg molecule was an order of magnitude higher than that of the same epitope in the N-part of the protein; the fact might be important for constructing artificial immunogens.

[Study of the process of thermal aggregation of several representative tobamovirus coat proteins]. / Izuchenie protsessa termicheskoi agregatsii belkov obolochki neskol'kikh predstavitelei tobamovirusov.

The role of the specific region of the tobacco mosaic virus (TMV) coat protein (CP) molecule (called "70A degree-region") in the regulation of ordered and unordered CP aggregation was investigated. CPs of the wild type TMV (strain U1), of temperature sensitive mutant with two amino acid substitutions in the "70A degree-region", and of cucumber virus 3 which is related to TMV but has a completely different structure in the "70A degree-region" were used. With the help of two different tests the processes of temperature-induced unordered aggregation of these three CPs were compared in solutions of different ionic strength and pH. On the basis of the data obtained it was concluded that the "70A-region" represents the most thermolabile region in the TMV CP molecule and that local thermal denaturation of this region results in unordered aggregation, when solution conditions (ionic strength and pH) favor formation of relatively large ordered aggregates (20S-"disks" or helical repolymerized protein).

[Benz(a)pyrenes and N-nitrosamines in dry dairy products]. / Izuchenie soderzhaniia benz(a)pyrena i N-nitrozoaminov v sukhikh molochnykh produktakh.

Results of works induding study of effect of different factors (environment, type of equipment, technology) on content of cancerogenic substances in dry milk products were summarized. Possible reasons of appearance of cancerogens in milk in process of drying were determined, dataes of concentration of benz(a)pyren and N-nytrozamens in milk and warmth carrier before and after drying were established. Explanation of separate appearances which connect with change of quantity of cancerogens in product on different stages of drying was suggested.

[Evaluation of a drying procedure for dairy products coming in direct contact with flue gases from the oncologic viewpoint]. / Onkogigienicheskaia otsenka tekhnologii sushki molochnykh produktov pri priamom ikh kontakte s dymovymi gazami.

The study was concerned with ambient air and heat-transfer medium levels of benzo(a)-pyrene (BP) and N-nitrosoamines (NA) measured at the input and output of the drying chamber of two milk dryers using different systems of heat generation. Said concentrations were ascertained in the dried product (casein), too. One installation used electricity-heated ambient air, while the other--air-diluted products of natural gas combustion. No significant difference was registered for both dryers between ambient-air and heat-transfer medium concentrations of BP and two NAs detected--NDMA and NDEA. There was no significant difference between BP levels in the casein produced on those installations, the raw material coming from the same lot. The study registered reverse changes in NDMA and NDEA concentrations, with ambient air being heated in the heat generator and heat-transfer agent cooled in the drying chamber.