equipment (braces) on the biochemical parameters of oral fluid. Materials and methods. The study involved patients aged 18 to 22 years who are undergoing orthodontic treatment with a bracket system. Thegroup of examined persons was 25 people. The control group included 15 practically healthy people without braces. All patients underwent dental status assessment (Green – Vermillion hygiene index – simplified IG-Y; PMA inflammation index), laboratory examination of oral fluid before and after controlled oral hygiene. The biochemical analysis included determination of the acid-base balance in the oral fluid using a pH meter, assessment of free radical oxidation by chemiluminogram parameters by biochemiluminescence and by levels of molecular products of lipid peroxidation (diene and triene conjugates, Schiff bases), activity of the enzyme alkaline phosphatase, concentrations of total protein and lactate. Results and discussions. In patients undergoing orthodontic treatment with a bracket system, an insufficient level of oral hygiene and inflammatory manifestations in the gums of moderate severity were revealed. The level of the acid-base balance of the oral fluid before controlled hygiene was equal to 6.8±0.19, that is, below the range of normal pH values in the oral cavity. After hygiene, the pH of the oral fluid returned to the norm of 7.1±0.2. In patients with braces, activation of free radical oxidation and an increase in lipoperoxidation parameters – triene conjugates and Schiff bases, increased activity of alkaline phosphatase, total protein and lactate levels took place.Cоnclusion. After hygienic treatment of the oral cavity, the biochemical parameters did not differ statistically significantly from the control data.