Aim. To determine the link between the clinical and radiological torque of the medial incisors in cases with physiological occlusion. Materials and methods. A measurement of the clinical torque values was performed (whereas the torque is defined as the deviation of the tooth crown vestibular surface from the occlusal plane) in 98 people with physiological occlusion and a full set of permanent teeth. When measuring the clinical incisor torque, three methods were employed. The first method allowed studying teeth torque in relation to the occlusal plane on the cast jaw models using the ArcoZet equipment (by Scheu Dental GmbH). The second method implied using a modified protractor, where the moving part was oriented in relation to the occlusal plane. The third method we used involved analyzing data from teleradiography and cone-beam tomograms obtained with the PaX-i3D SC digital panoramic X-ray unit (VATECH Global), which were marked with linear and angular reference points. The patients were divided into three groups depending on the incisors location: Group 1 included patients with the mesotrusive incisors location; Group 2 were patients with physiological protrusion of the incisors and a decrease in the interincisal angle, with Group 3 including patients with physiological retrusion of incisors. Results. Regardless of the type of dental arches and the vestibular lingual inclination of the incisors, the average difference between the clinical and the radiological incisor torque values is 26°, which can be used in clinical orthodontics to develop a treatment tactics and its effectiveness in people with various gnathic and dental types as well as with various dental arches. Conclusion. All methods used for measuring the teeth inclination angles in the vestibular lingual direction can be employed both in the applied and in the clinical aspect. Identifying the permanent teeth torque through cast models of dentition morphometry and through using special equipment, takes a lot of effort, time, at the same time being subject to potential measurement errors. The methods implying analysis of cone-beam computed tomography images feature high-tech reliance, precision, whereas the reproductive capacity and interpretation of the results allows using the available angular and linear parameters for evaluating the effectiveness of the respective orthodontic procedures through all the stages of treatment

sCanning eleCtron miCrosCopy and x-ray speCtral miCroanalysis in studying dental tissue resistanCe a b s t r a c t-Aim. Potential use of scanning electron microscopy with X-ray spectral microanalysis to determine the structural, functional and acid resistance of tooth enamel through mineralization stages. Materials and methods. A VEGA II LMU highresolution scanning electron microscope with an INCA Energy 350XT X-ray microanalyzer, were used to identify the degree of packing, size, and shape of enamel prisms and interprismatic intervals, as well as the content of chemical elements in the upper layer of permanent teeth enamel. Structural, functional and acid resistance of enamel was studied using the enamel resistance test (V.R. Okushko, 1984). The material used included 47 premolars (removed for orthodontic reasons) with no sign of carious lesions in children belonging to the age group of 11-16 with a mineralization period of 6-60 months from the time of eruption. Results. The results of X-ray spectral microanalysis regarding the chemical elements content in weight percent, revealed that through the maturation (mineralization) stages, the surface enamel layer featured a significant trend towards increasing the Ca, P, and F concentration, as well as Ca/P ratio, along with a decrease in the level of C, Na, O. An investigation into children undergoing the early stages of physiological maturation revealed that tooth enamel had a hypomineralized structure of the hydroxyapatites crystalline grid a with disturbed spatial orientation and boundaries accuracy, changed organic matrix depth, increased shell size and polymorphisms in the enamel prisms structure along with a reduced density of their packing. The combination of these signs is indicative of incomplete development of prismatic enamel structures with an unbalanced ratio of the mineral component and the organic matrix. Conclusion. The obtained results demonstrate potential use of high-resolution electron microscopy with X-ray spectral microanalysis to study dental hard tissues. Development and introduction of personalized approaches to caries prevention based on selective usage of remineralizing drugs and vitamin-mineral complexes, would improve resistance to caries through all stages of physiological maturation. K E y w o r d s-scanning electron microscopy, X-ray spectral microanalysis, caries resistance, enamel mineralization, enamel chemical composition.