**5. Orthodontic tooth movement and reorganization of blood vessels**

Blood vessels in periodontal ligament actively participate in the remodeling of dental tissues, which is related to the orthodontic tooth movement. Under the influence of mechanical forces, the reshaping of existing and creation of new blood vessels at periodontal ligament occur. These processes occur via numerous signal paths, which are activated after the deflection of ECM, which surrounds the cells of endothelia of blood vessels. They are mostly established via integrin of endothelial cells and ECM structures, which surround the blood vessels [14] and lead to the organization of endothelial cells unto multicellular pre-capillary network [11]. The response of blood vessels of periodontal ligament to the effect of mechanical forces is expressed by increased permeability, which, on its side, increases the fluid outpouring from capillary into the interstitial space [15]. These blood vessels play an essentially important role in aseptic inflammatory reaction caused by mechanical forces, acting as a source of inflammation mediators (cytokine and neurotransmitters), which mutually react with endothelial cells of periodontal capillary network encouraging them to bind circulating leukocytes and influence their relocation into periodontal ECM.

growth factor (epidermal growth factor—EGF), and neuropeptides (P-SP substance, calcitonin gene-related peptide—CGRP), which indicates the participation and mutual communication of cells of immune, endocrine, and nervous system in the regulation of the bone remodeling

The Role of Cytokines in Orthodontic Tooth Movement http://dx.doi.org/10.5772/intechopen.80078 39

The primary role in the initiation of a series of biochemical processes that stimulate or inhibit cellular activities during the inflammatory changes, initiated by the effect of orthodontic

**Figure 1.** The sequence of events in dental tissues during orthodontic tooth movement. ECM—extracellular matrix;

[16, 18–22].

PDL—periodontal ligament.
