FEATURES OF THE VARIATIVE MORPHOLOGY OF THE MANDIBULAR SECOND MOLAR USING CONE-BEAM COMPUTED TOMOGRAPHY IMAGING.

OBJECTIVE: The aim: To characterize the variations in the anatomical structure of the second lower molar. PATIENTS AND METHODS: Materials and methods: In order to determine the topography of the roots and root canals of the mandibular second molar, modern imaging methods were used: orthopan¬tomography and cone-beam computed tomography. RESULTS: Case report: During the analysis of the orthopantomogram of the patient, the three-root morphology of the root system of 37 teeth was revealed. That is, three roots were clearly visualized. After detecting an atypical shape of the root system of the mandibular second molar in the panoramic image, the patient was offered to perform cone-beam computed tomography (CPCT) for diagnostic purposes. Analysis by cone-beam computed tomography showed the presence of four mature roots of normal length, which were arranged in the shape of a diamond. CONCLUSION: Conclusions: The four-root configuration is considered a rare form for mandibular molars, but it should be considered in endodontic interventions and, if possible, in the planning of such interventions, use cone-beam computed tomography.

CHARACTERISTICS OF METAL ALLOYS PROPERTIES FOR DENTAL CASTING AFTER THEIR REPEATED REMELTING.

OBJECTIVE: The aim: To study clinical and experimental substantiation of the possibility of using cobalt-chromium and nickel-chromium alloys after repeated remelting for non-removable one-piece prosthetics. PATIENTS AND METHODS: Materials and methods: Experimental studies of Remanium GM 700 and Remanium CSe dental alloys have been carried out. To study the physical and mechanical properties of alloys, samples were obtained by sequential six-fold remelting in a Tiegelschleuder TS casting dental unit manufactured by Degussa. All samples were subjected to chemical analysis and metallographic studies by methods generally known in metallurgy, which included studies of microhardness, elasticity, tensile deformation, bending deformation and alloy structure after repeated remelting. RESULTS: Results: Thus, the obtained results of the chemical, physicomechanical and structural properties of the remelts indicate that the Remanium GM 700 and Remanium СSe alloys can be reused many times for the manufacture of one-piece orthopedic structures in that they are identical with certified alloys. CONCLUSION: Conclusions: In terms of structure, qualitative and quantitative composition of elements, physical and technological properties, the Remanium GM 700 and Remanium CSe alloys have been repeatedly remelted meet the requirements of materials used in biologically active environments of the patient's body. High-quality and cost-effective remelted multiple times Remanium GM 700 and Remanium CSe alloys can be recommended for use in practical prosthetic dentistry six times.

COMPARATIVE EVALUATION OF HISTOTOXICITY INDICATORS OF METAL ALLOYS FOR THE MANUFACTURE OF METAL CERAMIC DENTAL CONSTRUCTIONS.

OBJECTIVE: The aim: To carry out a comparative assessment of metal alloys for the manufacture of metal-ceramic constructions of dentures by determining the indicator of their histotoxicity. PATIENTS AND METHODS: Materials and methods: To identify the effect of metal alloys on cobalt and nickel bases on the tissue of organism, we carried out an experimental-morphological study of standard samples of metal alloys "Shot-alloy", "Remanium-2000", "Cerium", "Dent-NCB", "Cellite-N". RESULTS: Results: A careful histological analysis of the capsules formed around the metal alloy samples during two periods of the experiment showed that the healing time of the subcutaneous tissue was not the same. The most complete healing, that is, the formation of mature fibrous connective tissue, occurred during the implantation of the cobaltbased alloy "Remanium-2000" and the capsule formed at the end of the experiment around the implanted sample from the "Shot-alloy" alloy, and during the implantation of the "Cerium" alloy, healing the wound surface and the formation of a connective tissue capsule occurs fully than in previous cases. CONCLUSION: Conclusions: The analysis of the performed experiment testifies in favor of the point of view that the speed and quality of healing of damaged subcutaneous tissue upon the introduction of implanted research alloys depend largely on the individual chemical components that make up the alloys, or on their combination.

EPIDEMIOLOGICAL INDICATORS OF DENTAL MORBIDITY OF CHILDREN AS AN INDICATOR OF ADVERSE ENVIRONMENTAL INFLUENCE.

OBJECTIVE: The aim: Is to study the ecological and hygienic situation in the living area of 6-year-old children in terms of drinking water (micro- and macroelements), to identify its relationship with the state of mineral metabolism in children's mouths, prevalence and intensity of temporary and permanent caries. PATIENTS AND METHODS: Materials and methods:Clinical and laboratory studies were to study the objective condition of the teeth -intensity of dental caries according to the recommendations of the WHO and the method of T.F. Vinogradova. The hygienic condition of the oral cavity was determined by the indices Silness-Loe, Stallard. RESULTS: Results: The results of our studies have shown that the proposed therapeutic and prophylactic complex, which includes drugs of endogenous (Vitafluor) and exogenous use (osteovitis, deep fluoridation, toothpastes "Splat junior" and "Lacalut fluor"), improves the hygienic state of the oral cavity, increases mineralizing the potential of the oral fluid and, as a result, helps to reduce the intensity of dental caries in children. CONCLUSION: Conclusions: The data obtained indicated a high caries prophylactic efficacy of the proposed therapeutic and prophylactic complex for 6-year-old children living in the zone of hypophtorosis.

MINERALIZATION OF TEETH ENAMEL AFTER ERUPTION.

OBJECTIVE: The aim: The paper was aimed at the study of the processes of mineralization of the enamel of the permanent tooth after its eruption. PATIENTS AND METHODS: Materials and methods: To study the structure of the enamel of permanent teeth has been carried out using light and electron microscopy. The study of the process of the development of the primordia of the permanent teeth involved 10 culled puppies of 30-40 days of age. Microscopic, electron microscopic, immunohistochemical methods of research have been used to study the processes of histogenesis. RESULTS: Results: The studies show that in the postnatal period, the formation of the crown, externally covered with cuticular epithelium, marks the formation of the primordium of the permanent tooth at the follicle stage. After eruption of a tooth, different parts of its crown have three individual structural and functional barriers to enamel biomineralization. The first one is provided by the cuticular epithelium of the pitted areas of the crown, which ensures filtering of the salivary fluid from the protein deposit in the form of a pellicle. The second barrier is defined on the lateral and cuspidate surfaces of the enamel, where the cuticle is erased or poorly expressed. The third structural and functional barrier of enamel biomineralization is located in the cervical portion of teeth of different classes. CONCLUSION: Conclusions: Different areas of the enamel in the tooth crown have specific filtration barriers, which can be distinguished as follows: pit-and-fissure-and-groove, cuspidateand-approximal, and cervical barriers. The cuticle is poorly expressed or totally absent on the cusps of the tooth crowns in contrast to pitted areas.

WEAR RESISTANCE OF DENTAL MATERIALS WHICH ARE USED FOR ANTERIOR TEETH RESTORATIONS.

OBJECTIVE: The aim of this study was to compare the wear resistance of such restorative materials as composite resin, feldspathic ceramic, leucite glass ceramic with intact enamel and to draw an analogy with some similar researches. PATIENTS AND METHODS: Materials and methods: In this research 20 extracted human teeth (maxillary incisors) without fillings and carious cavities were used as samples. All samples were disinfected and stored in saline in order to prevent dehydration. Teeth roots were cut off for the measure of fixation on an organic glass plate using chemically polymerizable resin. If necessary, the teeth were also cut on their lateral sides in order to give them equal size. The samples were placed in a frame-holder, located on the lever of the machine MI-2, which determines abrasion resistance under slipping. RESULTS: Results: The research has revealed that the average wear resistance of natural teeth was 122,67±4.9 J/mm3 (Tab 1). The archived result overcomes dental composite resin twice more (62.8±1.21 J/mm3), feldspathic ceramic 6.5 times more (16.32±1.2 J/mm3) and leucite ceramic over the half (73.79±3.12 J/mm3). CONCLUSION: Conclusion: Thus, according to this performed research and the analysis of the relative literature sources it can be stated that dental composite resin and leucite ceramics may be proposed as the materials of choice for anterior restoration of teeth. They have shown the good wear resistance and tolerance to antagonizing natural teeth.

The intensity of chronic catarrhal gingivitis in children depending on the age.

OBJECTIVE: The aim: To determine the degree of severity of the inflammatory process in periodontal tissues of children living in different ecological conditions. PATIENTS AND METHODS: Materials and methods: With the purpose of estimation of the condition of periodontal tissues the epidemiology examination of 642 children that live on territory with the high level of pollution and natural deficit of iodine and fluorine was conducted. RESULTS: Results: The study found that the increase of age of examined children causes the decrease of percentage of easy degree of severity of chronic catarrhal gingivitis, giving way to the advanced forms of the disease, and this process was more pronounced in children living in ecologically polluted region. In children-inhabitants of ecologically clean region easy degree of severity of chronic catarrhal gingivitis met more often than their peers living in environmentally polluted region. At the same time, average and heavy degree of severity of chronic catarrhal gingivitis in children living in ecologically contaminated region met more often than their peers, inhabitants of ecologically clean region. CONCLUSION: Conclusions. It was found that with increasing age of the examined children decreases the percentage of chronic catarrhal gingivitis of moderate severity.

Features of the course of enamel biomineralization processes in various anatomical areas of the tooth.

OBJECTIVE: The aim: To establish the features of the structural organization of enamel in various anatomical areas of the tooth and determine their influence on the characteristics of the course of biomineralization processes. PATIENTS AND METHODS: Materials and methods: The study of the structural features of enamel and dentin was performed on thin sections of various groups of teeth. Then morphological, histochemical and electron microscopic examination methods were used. RESULTS: Results: The study found that there are three structural and functional barriers to biomineralization of enamel, which are located in different anatomical areas of the tooth crown. Each of them has both general and specific features. Enamel biomineralization is a continuous process of exchange of calcium ions, donor of which is brushite. The stepwise process of biomineralization turns the latter into calcium octaphosphate, which then turns into hydroxyapatite. The latter, when destroyed by carbon dioxide, forms carboxyapatite. CONCLUSION: Conclusions: In the result of conducted study was established peculiarities of enamel mineralization processes in different anatomical parts of tooth.

DENTAL CROWN BIOMINERALIZATION DURING ITS HISTOGENESIS.

OBJECTIVE: The aim: Thepaper wasaimedat thestudyof thebiomineralization processesofa permanentdental crown in thepostnatal period of histogenesis. PATIENTS AND METHODS: Materials and methods: The study involved 30 culled puppies aged 30-40 days. To study the histogenesis of the germs of the permanent tooth from the cuticular epithelium in the postnatal period microscopic, electron microscopic, immunohistochemical methods of study have been used. RESULTS: Results: The studies show that in the postnatal period, the maturation of the germ of a permanent tooth starts with the synthesis of cells of the cuticular epithelium of the organic stroma, capable of subsequent mineralization. Differentiation of the proameloblasts, located on the surface of the dental papillary mesenchyma, at the early stages of histogenesis, is strongly associated with the appearance of a specific protein taftelin. Origination of secretory ameloblasts, which produce the protein enamelin, triggers the process of secondary biomineralization of the enamel. The terminal processes of the secretory ameloblasts produce the protein in the form of layers that overlap each other at a certain angle. Such layering of the structures of enamel and dentin contributes to the S-shaped maturation of the hard tooth tissues, strengthening them considerably. At the follicle stage, maturation of the dental crown, coated with cuticular epithelium, occurs. Invaginations of the cuticular epithelium form a characteristic topography of the dental crown, and enamel projections are further formed by the ameloblasts. Epitheliocytes of the inner layer of the enamel organ have desmosomal connections that allow the filtration of the salivary fluid at the stage of the enamel trophism. CONCLUSION: Conclusions: The findings of the study suggest that, normally, due to the cuticular epithelium, filtration of the salivary fluid occurs with protein deposition on it and subsequent infiltration of the calcium salts into the subjacent enamel.