**4. Orthodontic tooth movement and the change in the structure of cytoskeleton**

The function of all cells in mechanic-sensitive dental tissues is closely related to the ECM, which surrounds them and makes the corresponding microenvironment for cell activities, which emerge after the application of orthodontic force. The orthodontic treatment leads primarily to ECM periodontium deflection, which results in the changes of cytoskeleton structure of cells anchored in ECM. ECM is multicomponent tissue, which enables the transmission of mechanical signals to the corresponding cells and thus the occurrence of changes in the structure and function of a certain tissue [11]. The structural components of ECM (collagen, fibronectin, laminin, elastin, proteoglycans, hyaluronic acid, etc.) bind with the adhesive receptors at cells called integrins, via which the mechanical stimuli are transmitted into the cell causing the changes of cytoskeleton structures. The application of mechanical force outside disturbs the integrin receptors at fiber areas of periodontal ligament and gingiva and bone cells (osteoblast, osteoclast, osteocytes), and their adaptive response may increase or decrease the creation of integral elements of ECM in them and thus influence the change of the mass and morphological appearance of the bone [13].
