Experimental Tooth Movement in Rats Following Application of Soluble Receptors to IL-1 and TNFalpha

Objective: Proinflammatory cytokines like interleukin-1 (IL-1) and tumor necrosis factor alpha (TNFalpha) are believed to play a role in root resorption following orthodontic tooth movement. The inhibition of cytokine activities e.g. by soluble receptors could be beneficial to reduce this unwanted side effect. Methods: Orthodontic movement of the upper left first molar was performed in 80 male Wistar rats using a coil spring offering 0,5 N. Starting at day -1, three groups of 20 animals each received daily intraperitoneally injections of 2ml of 1µ/ml soluble receptors a) to IL-1(sIL-RII) b) to TNFalpha (sTNFalpha-RI) and c) a combination of a) and b). 20 animals served as a control. After 3, 6, 9 and 12 days, animals were killed in groups of 5 each. The amount of tooth movement was registered and the maxillae were prepared for histological and histomorphometric analysis. Osteoclasts and odontoclasts were identified using TRAP-histochemistry and ED-1-immunocytochemistry. Additionally, serum concentrations for IL-1beta and TNFalpha were analysed using ELISA. Results: The amount of tooth movement was reduced in all experimental groups by about 50 percent. In the control group, serum concentrations for the cytokines were not influenced by orthodontic tooth movement. In the experimental groups, concentrations fluctuated over the experimental period. In all experimental groups the number of TRAP-positive cells including odontoclasts were reduced. The number and staining intensity of ED-1 immunoreactive cells were reduced in rats of the experimental groups. Conclusion: Systematic application of soluble receptors to IL-1 and TNFa reduced tooth movement and the number of osteoclasts and odontoclasts. Present research is focussed on possible influences of the cytokines on cellular activity. (Supported by the Deutsche Forschungsgemeinschaft Ja444/3-1)