The Expressions Of OPG And RANKL In Human Dental Follicle Cells In Vitro And Their Effects On Tooth Eruption

Tooth eruption requires the presence of the dental follicle, a loose connective tissue sac that surrounds the enamel organ, which is origined from the ectomesenchyme.It is critical in tooth eruption and formation of periodontal tissue.Tooth eruption requires the influx of mononuclear cells(monocytes) into the dental follicle to form osteoclasts that resorb alveolar bone to form an eruption pathway.Candidate moleculars affecting the procedure are Colony stimulating factor-1(CSF-1) , Parathyroid hormone-related protein(PTHrP) , Monocyte chemotactic protein-1(MCP-1), Interleukin-1 α (IL-1 α ), Epidermal growth factor(EGF), Transforming growth factor-β(TGF-β), Osteoprotegerin (OPG), Receptor activator of nuclear factor-kappa B ligand(RANKL) etc .These moleculars attract the monocytes to the dental follicle directly or indirectly. Wise found that the expression of OPG in rat dental follicle cells decreased at some special stage,and proved that CSF-1 and PTHrP can down regulate the expression of OPG.The decrease of OPG leads to the up regulation of RANKL/OPG ratio which promotes osteoclastogenesis and resoption of alveolar bone followed by tooth eruption.But it was a matter of controversy whether RANKL is expressed in...