Orthodontic tooth movement is dependent on osteoclast activity. Tumor necrosis factor (TNF)-α 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-α and 2 chemokines (MCP-1/CCL2, RANTES/CCL5) were evaluated in periodontal tissues. A significant increase in CCL2 and TNF-α 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.
Polymorphisms of the tumor necrosis factor alpha locus among autoimmune disease susceptible and resistant inbred rat strains
