Orthodontic treatment of dentoalveolar anomalies is car-ried out using fixed and removable appliances, which af-fects the homeostasis of the oral cavity and increases the risk of developing carious lesions of the enamel. Purpose of the study: comparative assessment of the level of oral hygiene and the prevalence of enamel carious lesions at the stage of orthodontic treatment using removable and non-removable appliances. Materials and methods:90 patients aged 18 to 35 years were examined: 45 patients of the 1st group, who were treated with aligners, and 45 patientsof the second group, who were treated with a bracket system. In all patients, the level of oral hygiene was determined by the OHI-S (Green-Vermillion) index, as well as the level of CPU before and after 12 months of orthodontic treatment. Results: before the start of orth-odontic treatment, the OHI-S index in patients of the first and second groups was 0.86±0.67 and 0.89±0.74 points, respectively. After 12 months, there was a deterioration in the parameters of oral hygiene to a greater extent in patients of the second group who were treated with a fixed technique: the OHI-S index was 1.98±0.79 points. The value of the CPU index before the start of orthodontic treatment in patients of the first and second groups was 7.1±1.32 and 6.9±1.46, respectively. After 12 months of orthodontic treatment, there was an increase in the CPU index in the studied persons of the second group, who were treated with a bracket system: the CPU index was 13.6±1.78. In patients of the first group, the CPU indica-tor practically did not change and amounted to 7.9±1.25. Conclusion: with high caries susceptibility and the pre-sence of non-carious enamel lesions, orthodontic treat-ment with removable appliances should be preferred in order to avoid the development of complications.