The most frequent dental signs of hypophosphatasia in children are premature loss of primary teeth, decrease in height of alveolar bone, and malocclusions. Enzyme replacement therapy with Asfotase alfa might be associated with stabilization of dental status. K E Y W O R D Sasfotase alfa, dental signs, enzyme replacement therapy, hypophosphatasia, premature loss of primary teeth 912 | KISELNIKOVA Et AL.

Objective. The cause of considerable elasticity and plasticity of human dentin is discussed in the relationship with its microstructure. Methods. Structural state of teenage and mature human dentin is examined by using XRD and TEM techniques, and their deformation behavior under compression is studied as well. Result. XRD study has shown that crystallographic type of calcium hydroxyapatite in human dentin (calcium hydrogen phosphate hydroxide Ca9HPO4(PO4)5OH; Space Group P63/m (176); a = 9,441 A; c = 6,881 A; c/a = 0,729; Crystallite (Scherrer) 200 A) is the same for these age groups. In both cases, dentin matrix is X-ray amorphous. According to TEM examination, there are amorphous and ultrafine grain phases in teenage and mature dentin. Mature dentin is stronger on about 20% than teenage dentin, while teenage dentin is more elastic on about 20% but is less plastic on about 15% than mature dentin. Conclusion. The amorphous phase is dominant in teenage dentin, whereas the ultrafine grain phase becomes dominant in mature dentin. Mechanical properties of human dentin under compression depend on its structural state, too.

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The purpose of the present cohort study was a quantitative assessment of the enamel, dentin, and alveolar bone mineral density (BMD) using Cone Beam Computed Tomography (CBCT) scans in patients with X-linked hypophosphatemic rickets (HLHR) and hypophosphatasia (HPP) and a comparison with the data obtained from the control group. Methods and Results: The unrepresentative, non-random sample included 30 CBCT scans of children with genetically and biochemically confirmed XLHR (OMIM #307800) and HPP (OMIM: 146300, 241510, 241500, and 146300). X-ray examination and dental care were carried out in the Radiology Diagnostics Department and Pediatric Dentistry Department at Moscow State University of Medicine and Dentistry named after AI Evdokimov. The mineral density of calcified tissues (enamel, dentin, and alveolar bone) was evaluated using i-CAT Vision TM software options on reconstructed CBCT axial views. The images of all XLHR and HPP patients visualized large pulp chambers with prominent pulp horns extending to the dentin-enamel junction. The present study revealed poor alveolar bone mineralization in patients with HPP and XLHR. Analysis of CBCT scans showed a significant dentine hypodensity in XLHR patients, which may contribute to the emergence of multiple, spontaneous, periapical abscesses spreading rapidly in the jawbone. Conclusion: Data obtained could be used for planning dental treatment of patients with XLHR and HPP.

Relevance. Early caries is one of the most prevalent childhood diseases worldwide. Up to 32% of three-year-olds have tooth decay, the prevalence of caries in 6-7-year-old children in different cities of Russia increases to 65%, while 55.7% of children have caries of permanent teeth. In order to improve the quality of dental care, it is necessary to receive information about the prevalence and intensity of dental diseases, taking into account medical geography. Purpose – to assess caries and fluorosis incidence rate in primary teeth, to determine the hygiene index and the level of dental care for children under seven years old living in regions with different fluoride concentrations in drinking water.Materials and methods. The study conducted dental examinations of 150 children living in the South-Eastern Administrative District of Moscow aged 1 to 6 years and of 200 children living in Krasnogorsk aged 1 to 6 years. The study included the patients based on the developed inclusion criteria and informed voluntary parent consent. We entered the data into the registration card, which noted the dental formula, the prevalence and intensity of caries, the hygiene index according to Fedorov-Volodkina, the level of dental care according to P.A. Leus (1987).Results. Children living in an area with a low fluoride concentration in drinking water show the first signs of caries by the first year of age, then there is a significant increase, observed in the group of 3and 6-year-olds. The prevalence of caries in 1-year-old children living in an endemic focus of fluorosis is almost two times lower than in children living in an area with a reduced content of fluorides in drinking water, in 3-4-year-old children – 1.5 times lower, and in 5-6-year-old children 2 times lower. Along with this, 16-year-old children living in the focus of endemic fluorosis, Krasnogorsk, Moscow region, revealed fluorosis of primary teeth with a prevalence of 27%.Conclusions. The results indicates the need to increase the frequency and quality of patient education and increase the level of dental care.