The Role of Tumor Necrosis Factor Receptor Type 1 in Orthodontic Tooth Movement

Orthodontic tooth movement is dependent on osteoclast activity. Tumor necrosis factor (TNF)-alpha plays an important role, directly or via chemokine release, in osteoclast recruitment and activation. This study aimed to investigate whether the TNF receptor type 1 (p55) influences these events and, consequently, orthodontic tooth movement. An orthodontic appliance was placed in wild-type mice (WT) and p55-deficient mice (p55(-/-)). Levels of TNF-alpha and 2 chemokines (MCP-1/CCL2, RANTES/CCL5) were evaluated in periodontal tissues. A significant increase in CCL2 and TNF-alpha was observed in both groups after 12 hrs of mechanical loading. However, CCL5 levels remained unchanged in p55(-/-) mice at this time-point. The number of TRAP-positive osteoclasts in p55(-/-) mice was significantly lower than that in WT mice. Also, there was a significantly smaller rate of tooth movement in p55(-/-) mice. Analysis of our data suggests that the TNFR-1 plays a significant role in orthodontic tooth movement that might be associated with changes in CCL5 levels.