Immunohistochemical localization of components of the insulin-like growth factor-system in human deciduous teeth

To investigate the occurrence of components of the insulin-like growth fact or (IGF) system during the resorption process of shedding human deciduous t eeth, we investigated sections of 13 decalcified and paraffin-embedded deci duous teeth immunohistochemically with antibodies against IGF-I and -II, si x IGF binding proteins (IGFBPs 1-6) and the IGF receptors IGF1R and IGF2R. The teeth were in different stages of resorption and all showed reparative cementum formation. It was found that acellular extrinsic fiber cementum, r eversal lines and reparative cellular intrinsic fiber cementum were immunor eactive for both IGFs and various IGFBPs. Therefore, in human deciduous tee th, all subgroups of cementum, but not dentine, may represent sources of co mponents of the IGF system. Odontoclasts did not carry IGFs or the IGF1R, b ut IGFBPs and the IGF2R. Therefore, these cells, in contrast to osteoclasts , may not respond to IGFs, but may be involved in the release and sequestra tion of IGFS from cementum during the resorption process. In contrast to od ontoclasts, cementoblasts and periodontal ligament (PDL) fibroblasts carrie d IGF1R. The influence of the IGF system on the function of these cells wit h respect to periodontal matrix turnover and cementogenesis is discussed. O n the behalf of the IGFBP immunoreactivities found, the PDL extracellular m atrix can be considered to be a reservoir for IGF system components, where binding proteins may regulate IGF distribution and activity.