The desensitizer creates a reliable hermitization of the dentine tubules and forms a film on the surface of the tooth, which prevents further erosion and destruction of dentine. Tokuyama Shield Force Plus has an instant desensitizing effect and reliably protects the tooth from further damage. In patients undergoing orthodontic treatment, due to the complexity of hygienic procedures, the processes of caries formation may be more active. The use of a desensitizer in such patients can significantly reduce the risk of developing this pathological condition. Aims. Evaluation of the effect of desensitizer on the oral cavity condition in patients undergoing orthodontic treatment. Materials and methods. The study involved 120 patients aged 18-30 years. Each patient underwent a general clinical and dental examination. The study participants were randomly divided into 4 equal groups depending on the bracket system and desensitizer used: group 1 - ceramic bracket systems without pretreatment of enamel with a desensitizer (n=30), group 2 – ceramic bracket systems with enamel desensitizer treatment (n=30), group 3 – metal bracket systems without the use of a desensitizer (n=30), group 4 – metal braces using a desensitizer (n=30). The assessment of the oral cavity was carried out before treatment, 1, 3, 6 and 12 months after the start of orthodontic treatment. Universal Bond adhesive system (Tokuyama Dental), SHIELD FORCE PLUS desensitizer (Tokuyama Dental), double-curing adhesive fixing cement ESTECEM PLUS (Tokuyama Dental) were used for gluing bracket systems.