An Influence Of Specific ODN On The Tooth Movement And Alveolar Bone Remodeling In Rats

Objective:The purpose of the present experiment is to study the effect of the specific sequence oligonucleotide (oligodeoxynucleotides, ODN) on the distances of tooth movement ;to study the changes of periodontium structure, and the expressions of RANKL and typeⅠcollagen which are contained in the periodontal tissue of the rats;then to investigate the effect of this specific ODN on the control of tooth movement and alveolar bone remodeling.Method:40 male Wister rats which were 7 weeks old (weight 221±18g) were randomly divided into experimental group and control group, n = 20. then according to the observation point, each group was divided into 3d, 7d , 14d, 21d, and 28d's observation group,n=4. Under the anchorage of rats'maxillary front teeth, established model of experimental tooth movement in rats in order to pull the maxillary first molar move mesial by the force of 40g.After that, the buccal gingival mucosa of the maxillary first molar of the experimental group was injected with 50μl ODN (20μg/ml), and the control group was injected with the same amount of PBS, administered once every 3d. The rats of each observation group of the experimental group and control group were killed on its observation point. The plaster models of rats'upper mandible were made to measure the distance of tooth movement , afer the tooth moving models were erected and before tha rats were killed.Then the maxillary first molar and its periodontium were got from the dead rats.By the way of HE stain and immunohistochemistry stain to observe the changes of periodontium structure, and the expressions of RANKL and typeⅠcollagen which were contained in the periodontal tissue.Results:①Besides the 3rd day , the moving distances of the first molars of the experimental groups were less than the control group, and the difference was statistically significant (P <0.05).②HE staining showed that the absorption of pressure side of the first molar alveolar bone in the the experimental group was less than the control group.Furthermore the number of osteoclasts was also less than the control group,especially the 7 th day (P <0.01). ③The image of immunohistochemistry staining revealed that expression of typeⅠcollagen , which was contained in the periodontal tissue of rats ,gradually increased to peak in the 14 th day, then decreased.The collagen typeⅠin the experimental group was greater than the control group, especially the day of 7 th,14 th and 21th(p <0.05).But the expression of RANKL in periodontium of both the experimental group and control group had its peak in the 7 th day,and then gradually decreased. Moreover the expression of RANKL of the experimental group were less than the control group, especially the day of 7 th,14 th and 21th (p <0.01),But in the day of 21 th and 28 th the the difference between the two groups had not statistically significant.Conclusion:In rats model of experimental tooth movement, the specific ODN can reduce the number of osteoclasts on the pressure side of the alveolar bone surface and inhibit experimental tooth movement. After that this specific ODN can also enhance the expression of typeⅠcollagen and reduce the expression of RANKL, which were contained by periodontal tissue. All of these show that the specific ODN can affect on the control of tooth movement and alveolar bone remodeling.