Abstract: To explore the immunohistochemical expression of IL-8 in pulpal tissues on orthodontic rapid tooth movement through distraction osteogenesis. MethodsFifteen nativehealthyhybrid dogs were randomly divided into 5 groups: 3 dogs in each group. The device was activated for 2 weeks (group A), the device was fixed for 1 week (group B), the device was fixed for 2 weeks (group C), the device was fixed for 4 weeks (group D) and the control group (group E). In the experimental groups, the second premolar was pulled out, and the first premolar served as the moving tooth and the third premolar served as another tooth. Then the first premolar of the experimental animals was moved by using distraction device and then was pulled out when the device was activated for 2 weeks, fixed for 1 week, 2 weeks, and 4 weeks respectively. Then immunohistochemical expression of IL8 in pulpal tissues was determined by ELISA method. ResultsThe IL-8 concentrations in group A were significantly higher than that in the control group（P<0.05）.After the device was fixed for 1 week, the IL-8 concentrations in group B significantly decreased, and significantly decreased in group C, there were significant differences from group A（P<0.05）but no significant differences from the control group（P>0.05）. ConclusionsThe immunohistochemical expression of IL-8 is significantly increased notably after experiment, and declined to the normal level 2 weeks after the device is fixed, indicating distraction osteogenesis of periodontal ligament can increase the orthodontic tooth movement.

Key words: Distraction osteogenesis of the periodontal ligament, Interlukin-8, Orthodontic rapid tooth movement