A Comparative Study for Localization of Odontoclast in Crown and Root of Physiological Resorbed Primary Teeth

Root and crown resorption is a physiologic event for the primary teeth. It is still unclear whether odontoclasts, the cells which resorb the dental har d tissue, are different from the osteoclasts, the cells that resorb bone. Dental tissue resorption seems to be initiated and regulated by the stellate reticulum and the dental follicle of the underlying permanent tooth via the secretion of stimulatory molecules, i.e. cytokines and transcription factors. The primary teeth resorption process is regulated in a manner similar to bone remodeling, involving the same receptor ligand system known as RANK/RANKL (receptor activator of nuclear factor-kappa B/ RANK Ligand), which represent two cytokine-like proteins of the tumor necrosis factor superfamily, are localized on bone cells and dental cells .They are crucial for the regulation of osteoclastic/odontoclast cell differentiation and also for the upregulation of mature osteoclasts/odontoclasts mediated by cell-to-cell contact and a subsequent cascade of diverse intracellular signaling processes .The aim of the present study was to localize and compare the IHC rea ctions for RANKL along root surface and the crown of human phs iological resorbed primary teeth. Fifteen human upper deciduous (second molar) teeth ,undergoing root and crown resorption wer e used for immunohistochemical study to identify RANKL expre ssion. The results demonstrated a high mean of expression of R ANKL in root as compared with crown in human primary shedding teeth. The present study concludes that RANKL play a role in res orption process of the primary teeth.