An Experimental Study Of Adiponectin Inhibiting The Relapse After Orthodontic Tooth Movement

Objective:Previously, we discovered that adiponectin regulates bone remodeling via RANKL/OPG signaling during orthodontic tooth movement. But the mechanism of recurrence after orthodontic tooth movement is not yet clear. Our objectives were to determine the effects of adiponectin on relapse and the periodontal tissue remodeling after experimental tooth movement in rats and to explore the molecule mechanism. In order to provide an effective way for decreasing the extent of relapse after tooth movement, accelerating teeth stable soon in the new position.Methods:Forty adult male SD rats were randomly divided into 2 groups, the right maxillary first molars were moved mesially with nickel-titanium closed-coil springs in both group. On the 21st day, the springs were moved and the dental casts were made. Animals in the experimental group began receiving adiponectin at a dose of 10μg every two days in the buccal submucosal area of the first molar, and the animals in the control group received PBS. The results were evaluated by model measuring and immunohistochemistry on day 1,3,7,10 and 14. The experimental results were analyzed by statistical software SPSS16.0.Results(1) The distance of tooth relapse:The distance of tooth relapse was increased with the increased of experiment time. Relapse distance and relapse percentages in the adiponectin group was significantly lower compared with controls on day 7,10 and 14 (P<0.01).(2) HE staining:The phenomenon of bone formation of the experimental group were more significant than that of the control group, such as the number of osteoblasts, bone formation, hematoxylin stained line, periodontal ligament.(3) Immunohistochenmical examination reveals:On the mesial side, the expression of OPG in the experimental group were stronger than the negative control group from day 7 to day 14 (P<0.05). The expression of RANKL in the experimental group were less than the control group, but they were no significant difference.The mean ratio of RANKL/OPG was less than 1 in both group, and experimental group was more less than the control group (P<0.05).On the distal side, the expression of RANKL, OPG and the mean ratio of RANKL/OPG decreased from day 1 to day 3. In the experimental group the expression of RANKL were lower than of the control group. On the contrary, the expression of OPG was slightly stronger. The mean ratio of RANKL/OPG was more than 1 in both group, and control group are more than the experimental group (P<0.05).Conclusions:Adiponectin by local administration of a dose of 10μg every two days inhibits the expression of RANKL while promoting the expression of OPG. The results indicate that adiponectin stimulates bone formation while reducing the extent of the moved tooth relapse, probably by controlling the ratio of RANKL/OPG in the periodontal tissues. Therefore, adiponectin may be an useful agent for the pharmacological assistance of retention period.