Bindiuhin O. Prevention of relapse of the crowding of the teeth in the retention phase of the orthodontic treatment

The dissertation is devoted to the study of features of the clinical course of the retention period after the completion of the active phase of orthodontic treatment in adolescents aged 13-17 years (158 patients) and finding ways to improve its effectiveness. It was found that patients with different types of skeletal jaw growth have the highest tendency to relapse in the retention phase of treatment, which according to the cephalometric examination have the highest values of inclination angle of the mandible plane ML / NSL (35.8 – 36.7± 2.0 °) N = 33 ° and decrease in Overbite Depth Indicator (65-67 ± 2.0 °) N = 74.5. Patients with horizontal growth type (p <0.01), on the contrary, have lower values of inclination angle of the mandible plane ML / NSL (28.7-29.5 ± 2.0 °) N = 33 ° and increase in ODI (Overbite Depth Indicator ) (75.5–77.8 ± 2.0 °) N = 74.5 °, among which 3 cases of recurrence of dental congestion were diagnosed as a result of complications from influence of the fixed orthodontic retainers. The study expanded the scientific concepts of the application of the method of diagnostics of the optical density of bone tissue in different types of jaw growth in children in early permanent occlusion according to densitometry (Hounsfield method). Important to prevent the development of recurrence of dental congestion is the established fact that obtained in the process of densitometric studies values of the optical density of the spongy bone revealed statistically significant differences between patients with different directions of jaw growth. The values of cortical plate optical density in the frontal area were 800 ± 0.4 HU and 1047 ± 0.3 HU, respectively, in patients of the first and second groups; the values of the densitometric indices of the spongy part of the alveolar sprout varied from 475.4 ± 0.4 HU to 510.02 HU according to the patients of the first and second groups; mean optical density values were diagnosed within the range of 412.2–750.4 HU, which indicated significant differences in the bone structures of patients in the first and second major retention groups. In the course of the study, it was found that in the retention phase of treatment, the total optical density is higher than the measurements made in the active phase of treatment. Of great importance is the fact that the obtained values of the optical density of the spongial part of the alveolus in patients with vertical growth are lower than in patients with horizontal growth, respectively, 470 HU to 510 HU, which can be considered one of the causes for relapse. Clinical monitoring, biometric data of models, analysis of cephalometric indicators and the values of densitometric measurements in adolescents with relapsed crowding and lack of relapse in the retention phase, indicate the effectiveness of the proposed additions to the orthodontic retention protocol.