THE OCCURRENCE OF SPORTS INJURIES AMONG PRE-ADOLESCENTS.

Preschool children's harmonious development, cognitive and communicative abilities are enhanced through physical activities in sports, yet sports training and competition pose a risk of injury to children aged three to seven years due to their physiological and psychological features. Although sports injuries in preschool children are not common, they can be undesirable and unavoidable, and fortunately, these injuries are usually reversible. This review article presents data on the physiological features of the developing musculoskeletal system and its relationship to sports injuries in children, which together determine the nature of children's sports injuries. We also present a classification of sports injuries among preschool children, based on the literature, which considers the type, location, and severity of the trauma as estimated by the duration of mandatory missed practice.

СOMPARATIVE SPECTROPHOTOMETRY ANALYSIS OF ZIRCONIUM DIOXIDE WITH THE CUBIC AND TETRAGONAL PHASE AFTER ARTIFICIAL AGING.

Aim - to evaluate optical features of the 3, 4 and 5Y-TZP zirconium dioxide with the spectrophotometry analysis under artificial aging procedure. For all experiments, identical standardized specimens of different types of zirconia with a diameter of 10 mm and a height of 1 mm were used. These types included Katana (Kuraray Noritake Dental, Tokyo, Japan) HTML (control) UTML, STML and ZirCAD Prime (Ivoclar Vivadent). Artificial aging (low-temperature degradation) was performed using the following autoclaving regime: 134 degrees Celsius, 2 atmospheres, 5 hours. A Shimadzu UV-3600 spectrophotometer was used to study the spectral characteristics of the provided samples. Since the samples have low bandwidth, it was decided to investigate the reflectance spectra. For this purpose, a Shimadzu SR-1503 integrating sphere was installed on the spectrophotometer. Results: All samples of Prime manufacturer show an increase in the reflected signal intensity in the range of 650-820 nm. This range corresponds to red and orange colors, which means that as a result of autoclaving the beige tint of the materials will become more pronounced. The intensity of scattered light of the sample UTML-glaze and STML-glaze has lower values in the whole visible wavelength range. However, the intensity decrease in this case is not uniform. In the range above 500nm the intensity decrease is more pronounced, which means that as a result of artificial aging the beige tint of the materials will become somewhat less pronounced. Zirconia restorations with a predominantly tetragonal phase with polished and glazed surfaces will not change reflectance during artificial aging.

MEDICAL AND SOCIAL ASPECTS OF PREVENTING SPORTS INJURIES AMONG CHILDREN AND ADOLESCENTS.

Sports injuries among children and adolescents typically involve mild bruises and sprains. However, any sport can cause injuries to the musculoskeletal system. It is crucial to prevent such injuries through proper training and supervision to ensure the safety of young athletes. Therefore, when providing medical care to these patients, physicians must have the appropriate qualifications and skills and take into account the specific nature and location of injuries in each sport. Training programs and performance standards for young athletes should consider participants' biological age, physical and psychological immaturity, rather than their chronological age to prevent serious musculoskeletal injuries in child and youth sports. This review outlines the incidence of sports injuries in adolescents and considers how biological and social factors (factors related to coaches, peers and parents), influence the incidence and nature of injuries in different sports. Coaches and parents, though, have the ability to reduce the risk of injury by selecting suitable sports activities, employing the right equipment, enforcing rules, promoting safe playing conditions, and ensuring adequate supervision. Healthcare providers involved in the prevention and treatment of injuries in young athletes must possess the skillset to diagnose and assess the severity and risk to the athlete's future health and performance.

EFFECT OF SURFACE TREATMENT PROTOCOLS OF ZIRCONIUM DIOXIDE MULTILAYER RESTORATIONS ON FUNCTIONAL PROPERTIES OF THE HUMAN ORAL MUCOSA STROMAL CELLS.

Aim - to study the effect of protocols of surface treatment of zirconium dioxide multilayer restorations on the functional properties of stromal cells of the human oral mucosa using molecular biological methods. For all experiments, identical standardized specimens of different types of zirconia with a diameter of 10 mm and a height of 1 mm were used. These types included Katana (Kuraray Noritake Dental, Tokyo, Japan) HTML (control) UTML, STML and ZirCAD Prime (Ivoclar Vivadent). DMEM/F12 growth medium (Paneco, Russian Federation) with addition of fetal calf serum (Gibco, USA) up to 10% and penicillin-streptomycin (Paneco, Russian Federation) up to 1% was used in the experiment. Cells were detached from the culture substrate with trypsin-EDTA solution (Paneco, RF) and their number and viability were assessed using an automatic counter TC-20 (Bio-Rad, USA). For repopulation, samples were transferred into wells of a 96-well culture plate (1 sample in 1 well) and cell suspension was layered at the rate of 12.5 thousand or 25 thousand live cells per well. After 48 hours, the cytotoxic properties of the tested samples were evaluated in vitro. According to the results of MTT test we can conclude that samples of ZirCad Prime and Katana UTML groups do not show cytotoxic properties (score "0" on the cytotoxicity scale according to GOST R ISO 10993-5-2009 "National Standard of the Russian Federation. Medical devices. Evaluation of biological effect of medical devices. Part 5. Studies on cytotoxicity: in vitro methods"). The samples of Katana STML group samples were slightly reduced compared to the control (about 12%), nevertheless, these samples can also be considered non-cytotoxic. Analyzing the direct contact with the material in all samples, a good occupancy of the material by cells was observed, in particular, the polished surface prevailed over the glazed one, however, this difference is not statistically significant. Analysis of human oral stromal cells to zirconium dioxide showed no statistically significant effect of different surface treatment protocols. However, the number of fibroblasts prevailed on the polished surface.

Metastable extension of the liquid-vapor phase equilibrium curve and surface tension.

The method of molecular dynamics has been used to calculate the parameters of liquid-vapor phase equilibrium and the surface tension in a two-phase system of 4096 Lennard-Jones particles. Calculations have been made in a range from the triple point to near-critical temperature and also at temperatures below the triple point corresponding to the metastable equilibrium of a supercooled liquid and supersaturated vapor. To determine the surface tension, along with a mechanical approach a thermodynamic one has been used as well. The latter was based on calculation of the excess internal energy of an interfacial layer. It has been shown that in accuracy the thermodynamic approach is as good as the more sophisticated mechanical one. Low-temperature asymptotics of the phase-equilibrium curve and also of liquid and vapor spinodals have been considered in the Lennard-Jones and the van der Waals models. The behavior of the surface tension and the excess internal energy of an interfacial layer at T-->0 is discussed.