Relevance. The prevalence of various types of orthodontic pathology among the Russian population is quite high. Depending on the region, malocclusion are registered in 30.9% to 76.5% of cases. The high prevalence of orthodontic pathology and the unresolved issues related to both the pathology itself and the presence of concomitant diseases indicate the necessity for personalized methods of prevention and treatment of malocclusion during both the primary and mixed dentitions, which in 70-84% of cases are treated using both removable and fixed orthodontic appliances.Materials and methods. An observational study was conducted to identify factors contributing to the increased intensity of caries among children aged 6 to 11 with orthodontic pathology. The study evaluated the characteristics of hygiene knowledge and skills, as well as the Approximal Plaque Index (API), in children using various orthodontic appliances. To assess hygiene knowledge levels, a survey was administered to two groups of children aged 6-11: those undergoing orthodontic treatment and those who visited the dental clinic for a routine check-up and were diagnosed with orthodontic pathology. The questionnaire included questions about the primary and supplementary tools and practices for daily oral hygiene, the frequency of hygiene activities, and the patients' awareness of the importance of professional oral hygiene.Results. Factors that statistically significantly influence the level of hygiene and the Approximal Plaque Index (API) were identified. A computer program was developed to forecast the dynamics of oral hygiene levels (based on the API index) when using different orthodontic appliances. An algorithm for predicting changes in the API hygiene index was created, considering the use of orthodontic appliances, oral status, adherence to hygiene procedures, presence of harmful habits, and dietary behaviors. Negative factors significantly impacting hygiene levels include bruxism and daily consumption of sweets, while positive factors include adherence to the recommended frequency and duration of tooth brushing (at least twice a day) and the use of a medium-hard toothbrush when permanent teeth are erupting. During orthodontic treatment, additional negative factors impacting hygiene status include gingival bleeding (gingivitis), lack of lip closure, and harmful habits. The study of changes in hygiene levels over one year of treatment with various orthodontic appliances (braces, Haas appliance, SPA) showed that the fixed Haas appliance for treating dental and maxillofacial anomalies is the most favorable orthodontic design for mixed dentition.Conclusion. Factors significantly affecting the level of oral hygiene have been identified. The dynamics of the API hygiene index with various orthodontic appliances have been established. The most favorable appliance for mixed dentition is the HAAS appliance for rapid palatal expansion.
