Changes in vascular system during experimental tooth movement

Orthodontic tooth movement is characterized by remodeling changes in dentai and paradental tissues, including dentai pulp, periodontal ligament (PDL), alveolar bone, and gingiva. These tissues, when exposed to varying degrees of magnitude, frequency, and duration of mechanical loading, express macroscopic and microscopie changes. The activation of thè vascular System in thè compressed PDL is an indispensable process in periodontal remodeling during orthodontic movement. The initial response of thè mechanically compressed or expanded periodontal tissue is release of vasoactive neu-ropeptides, thè blood vessels respond with increased of permeability and extravasation of leukocytes into thè interstitial tissue and activation of a variety of osteogenic cells. The aim of this study was to clarify thè involvement of Vascular endothelial growth factor (VEGF) in periodontal tissue remodeling during orthodontic tooth movement. Vascular endothelial growth factor (VEGF) is mediator for angiogenesis, exert various biological functions such as vascular permeability and migration of human monocytes and is involved in bone resorption and formation. For thè study we utilized a coilspring NiTi 50 gr. and in vivo samples of 15 maxillaries and mandibolar premolars of patients aged from 13 to 18 years subject to orthodontic treatment. These teeth was extracted at 7and 21 days from application of force respectively The extraction of thè PDL was ef-fectuated scarifying thè radicular surface on thè pressure and tension side. The results were compared with periodontal ligament samples of thè normal homologous teeth (control). The periodontal ligament samples were fixed in 3% paraformaldehyde in a 0,2M phosphate buffer at pH 7,4.The following primary antibodies mouse monoclonal anti-VEGF were used. Section were then observed and photographen using Zeiss LSM 510 confocal microscope. Were analyzed fluorescence intensity and compared with thè control side. In thè compressive side were strongly positive for VEGF at 1 wk after thè start of tooth movement, suggesting that VEGF may be involved in thè early stages of periodontal remodeling during orthodontic tooth movement, when occur rapid changes in locai blood circulation. Moderate VEGF expression was also evident on thè tension side. In thè last observation periods at 21 days, VEGF signal showing insignificant de-crease when compared with thè control group. This can correspond to thè period of regenerative processes in these same tissues which comprises deposition of new bone, with new regenerated fibrillar elements, which in turn replaces thè previously increased vascular volume to control levels. These findings suggest that VEGF plays a cruciai role in periodontal remodeling during orthodontic tooth movement by acting directly on bone resorption and formation and on angiogenesis.