Abstract: Objective: To investigate the expression of vascular endothelial cell growth factor (VEGF) in the immediate replantation of pulp healing in the rats, and to clarify the effect and its mechanism of erythropoietin (EPO) on immediate pulp reconstruction in the rats. Methods: Eighty 4-week-old healthy male Wistar rats were randomly divided into non-tooth extraction group, negative control (normal saline) group, positive control (gentamicin) group and EPO group;there were twenty rats in each group.The teeth in each group were immersed in its corresponding solution for 4 min before replantation. Four rats were killed on the days 3, 7, 14, 21 and 28, respectively, and the specimens were made in the operation area. HE staining was used to observe the pulp revascularization in different time periods. Immunohistochemical staining was used to observe the protein expression levels of VEGF in odontal tissue of the rats in each group in different time periods. Results: The HE staining results showed that compared with non-tooth extraction group, the pulp tissue of replanted teeth of the rats in normal saline group had more inflammation, less root development, less restorative dentin and cementum deposition, and wider apical pores; the inflammation of pulp tissue of replanted teeth of the rats in gentamicin group and EPO group was mild, and the root development was relatively good; there were more deposits of restorative dentin and cementum, and the apical pores were narrowed. The immunohistochemical results showed that compared with non-tooth extraction group, the positive expressions of VEGF in odontal tissue of the rats at the days 3, 7 and 14 in the other groups were strong. Afterwards, the positive expression levels of VEGF were decreased gradually with the prolongation of time. The average optical density (AOD) of VEGF positive area indicated that EPO group > gentamycin group > normal saline group > non-tooth extraction group. Compared with non-tooth extraction group, the protein expression levels of VEGF in odontal tissue of the rats in normal saline group, gentamicin group and EPO group at 3, 7, 14 and 21 d after operation were significanty increased (P<0.05), but the protein expression levels of VEGF in odontal tissue of the rats at 28 d had no significant differences (P>0.05). Compared with normal saline group, the protein expression levels of VEGF in odontal tissue of the rats in gentamicin group and EPO group at 3, 7, 14 and 21 d after operation were significantly increased (P<0.05), but the protein expression levels of VEGF in odontal tissue of the rats at 28 d had no significant differences (P>0.05).Compared with gentamicin group,the protein expression levels of VEGF in odontal tissue of the rats in EPO group at every time points had no significant differences(P>0.05). Conclusion: EPO can increase the expression of VEGF, induce angiogenesis in pulp tissue, and provide the rich vascular bed for replantated teeth, so as to exert the potential of dental pulp defense and repair, and promote the healing of replanted teeth.

Key words: erythropoietin, replanted of teeth, pulp revascularization, vascular endothelial cell growth factor