Objective  To detect the effect of erigeron breviscapus on the expression of vascular endothelial growth factor（VEGF） in the periodontal tissues during

orthodontic tooth movement. Methods  45 rabbits were divided into 3 groups（groups A, B and C）. Groups A and B included experimental group of 1, 3, 7 and 14 days respectively. The mandibular first molar of each experimental rabbit was observed. The rabbits of group A and group B received iontophoresis with erigeron breviscapus  into the right（group A-R and group B-R） and with normal sodium into the left as the control（group A-L and group B-L）. Additionally, the rabbits of group B were designed orthodontic appliance, by which 0.78 N mesial force was applied to pull the mandibular first molars. Group C, group of 0 day, was no iontophoresis and  orthodontic appliance as the control. After killed on schedule, the amount of experimental tooth movement was measured and the expression of VEGF was examined by  immunohistochemical method. Results  The amount of experimental tooth movement increased successively from 1 to 14 days. The differences among days 3, 7 and 14  were significant in the comparison between group B-R and group B-L（P<0.01）. The expression of
VEGF in groups A-R and B-L enhanced apparently compared with that in groups C and A-L（P<0.01）, but that in group B-R was the most apparent（P<0.01）. The expression of VEGF reached the peak level on day 3 in groups A-R and B-R（P<0.01）, but it reached the peak level on  day 7 in group B-L（P<0.01）. Conclusion  Erigeron breviscapus by iontophoresis can accelerate orthodontic tooth movement, and can meanwhile up-regulate the  expression of VEGF in periodontium in the earlier period of orthodontic tooth movement. Thus it can be presumed that one of its mechanisms for erigeron breviscapus to

accelerate orthodontic tooth movemen is erigeron breviscapus effects the metabolism and differentiation of osteoblast and osteoclast through up-regulating the

expression of VEGF in periodontium.