Osteoblast Lineage Cells And Periodontal Ligament Fibroblasts Regulate Orthodontic Tooth Movement That Is Dependent On Nuclear Factor-Kappa B (Nf-Kb) Activation

Objectives: To investigate the role of NF-kappa B in osteoblast lineage cells and periodontal ligament (PDL) fibroblasts during orthodontic tooth movement (OTM).Materials and Methods: Transgenic mice that expressed a dominant negative mutant of the inhibitor of kB kinase (IKK-DN) with lineage specific expression in osteoblastic cells and PDL fibroblasts driven by a response element in the collagen1 alpha 1 promoter and matched wild-type (WT) mice were examined. A 10-12 g force was applied by a NiTi coil and maintained for 5 or 12 days. OTM distance, PDL width, and bone volume fraction were measured using micro computed tomography. Osteoclast numbers were counted in tartrate-resistant acid phosphatase-stained sections. Activation of nuclear factor kappa B (NF-kB) was assessed by nuclear localization of p65, and the receptor activator of nuclear factor-kappa B ligand (RANKL) was measured by immunofluorescence and compared to control specimens with no orthodontic force.Results: OTM-induced NF-kappa B activation (p65 nuclear localization) in WT mice was largely blocked in transgenic (TG) mice. OTM was significantly reduced in the TG mice compared to WT mice along with reduced osteoclastogenesis, narrower PDL width, higher bone volume fraction, and reduced RANKL expression.Conclusions: Osteoblast lineage cells and PDL fibroblasts are key contributors to alveolar bone remodeling in OTM through IKKb dependent NF-kappa B activation.