Tumor necrosis factor-α enhances the expression of vascular endothelial growth factor in a mouse orthodontic tooth movement model

Abstract

Background/purposeTooth movement that is achieved using orthodontic mechanical principles relies on bone resorption which takes place on the compression side via osteoclasts. Tumor necrosis factor-α (TNF-α) has been known to affect osteoclast formation in orthodontic tooth movement (OTM). Vascular endothelial growth factor (VEGF), which is one of the mediators of angiogenesis, also plays an important role in OTM by inducing vascular permeability and chemotaxis of osteoclast precursors. Therefore, the purpose of this research was to evaluate the effect of TNF-α on VEGF expression during OTM. Materials and methodsIn order to demonstrate the effect of TNF-α on VEGF expression during OTM, a nickel titanium closed coil spring was fixed to the upper left first molar and the alveolar bone beneath the upper incisors of both wild type (WT) and TNF receptors (TNFRs) deficient mice resulting in a mesial movement of the molar for 12 days. The maxilla was removed for histological analysis and real-time RCR analysis of VEGF expression. ResultsImmunohistochemical analysis revealed that there were fewer VEGF-positive cells in the periodontal membrane on the mesial side of the distobuccal root in TNFRs-deficient mice than that in WT mice during the OTM for 12 days. Furthermore, expression of VEGF mRNA is lower level in TNFRs-deficient mice than that in WT mice. ConclusionOur results indicate that TNF-α plays an important role in VEGF expression during tooth movement.