An immunohistochemical study on DNA synthesis in the periodontium during tooth movement in dog

Kim, Seong Jin; Lim, Na Won; Kim, Sang Cheol

Abstract

The purpose of this study was to investigate the changes about the cellular activity on DNA synthesis in the periodontal ligament of dog, in which experimental tooth movement was performed. A control and 5 experimental dogs, one and half year in age, were studied, Light force (50-75g) was applied by placing open-coil spring between left mandibular premolars; heavy force (250-300g), between right mandibular premolars, Experimental dogs were sacrificed after infusion of bromodeoxyuridine(BrdU), at 12 hours, 1, 3 ,7 and 14 days after force application, respectively. And the histologic and the immunohistochemical evaluation were performed on the obtained periodontal tissue around mandibular premolars, using anti-bromodeoxyuridine antibody, which can indicate proliferating cells. The results were as follows: 1. The tearing of periodontal ligament and the vascular dilatation at tension side were observed in 12 hours, increasing until 3 days. After then it decreased; Such a finding was more evident in heavy force group than in light force group. 2. The hyalinization of the periodontal ligament and the activity of osteoclast at pressure side were observed in 12 hours, increasing until 3 days. But from 7 days on, it decreased; Such a finding was more evident in heavy force group than in light force group. 3. The BrdU expression in the control group was positive, mainly in the oral epithelium and the fibroblasts in the periodontal ligament, but negative in bone cells in periodontal ligament. 4. The BrdU expression in the experimental group was more positive in tension side than in pressure side; The expression was a little more positive in the periapical area than in the cervical area of tooth. 5. The BrdU expression in light force group was the highest in 1 day, after which it decreased; In heavy force group, it was the highest in 12 hours, after which it decreased. But in 14 days, there was no difference between the experimental group and control group.