IMMUNOCYTOCHEMICAL LOCALIZATION OF FIBRONECTIN AND A 165-KDA MEMBRANE-PROTEIN IN THE ODONTOBLAST LAYER UNDER INITIAL CARIOUS LESIONS IN MAN

The possible role of fibronectin in dental tissue repair was investiga ted by comparing its distribution and that of the 165-kDa fibronectin- binding membrane protein (165 kDa-FnBP) in odontoblasts underlying car ious and sound dentine. By immunoperoxidase and light microscopy, fibr onectin was localized in the dentine underlying the carious lesion, ma inly on the surface of the tubule walls, whereas it could not be detec ted in neighbouring sound zones. The antibody to the 165 kDa-FnBP stro ngly reacted with the membrane of odontoblasts underlying the lesion, although those facing sound dentine did not express this antigen. Ultr astructurally the 165 kDa-FnBP was localized in the cell membrane at t he apical portion of odontoblasts, including the process membrane, ben eath the initial lesion; fibronectin was detected in the dentinal area close to the process, and also in contact with its external surface. By a high-resolution immunogold procedure, the proteins were colocaliz ed at the external surface of odontoblast processes. These data sugges t that fibronectin present in human carious dentine could modulate the behaviour of underlying odontoblasts by means of newly expressed 165 kDa-FnBP.