Abstract: Objective: To examine the expression of periodontal ligament-associated protein-1 (PLAP-1) and bone morphogenetic protein-2 (BMP-2) in the periodontal tissue of rats during the orthodontic tooth movement. Methods: A total of 36 male SD rats were allocated into 6 groups evenly, d1, d3, d5, d7, d14, d21. The power of 50g was applied on the left maxillary first molar, and the distance of orthodontic tooth movement was measured on the different time. HE staining and immunohistochemical sp method were used to detect the morphological changes, the expression of PLAP-1 and BMP-2 of the periodontal tissue at different time points. Results: The distances of orthodontic tooth movement were different significantly among 6 groups. HE results showed no significant changes in the periodontal tissue in control groups in different time; while in the experimental group, osteoblasts were regenerated in the tension side and osteoclasts regenerated in the compressive side of periodontal tissue. The expression of PLAP-1 on both sides reached the peak on the 3d in the experimental group, and higher on the tensional side than the compressive side, there existed significant difference among all the groups except for the 21d group. The expression of BMP-2 on both sides reached the peak on the 5d in the experimental group, and higher on the tensional side than the compressive side. Conclusion: The expression of PLAP-1 and BMP-2 reached the peak at different time points.

Key words: Periodontal, ligament-associated, pprotein-1, Bone, morphogenetic, protein-2
Orthodontic, tooth, movement, Immunohistochemistry, Periodontal, ligament