Organic-inorganic relationships, and immunohistochemical localization of amelogenins and enamelins in developing enamel.

The organic-inorganic relationships in calf molar immature enamel, and the localization of amelogenins and enamelins in its matrix, have been studied by post-embedding decalcification and staining (PEDS) method and the immunohistochemical protein A-gold technique, respectively. Filament- and ribbon-like organic structures similar in shape, location and orientation to untreated crystals (crystal ghosts) were shown by PEDS method in immature enamel matrix. Immunohistochemical technique showed that amelogenins were not masked by inorganic substance, because they were reactive both in undecalcified and decalcified sections, gold particles being mainly located at intercrystallite regions; on the contrary, enamelins were masked by inorganic substance because they were reactive only in decalcified sections, gold particles being sometimes closely related to filament- and ribbon-like crystal ghosts. These results are in agreement with those of previous morphologic studies, showing that crystals of immature enamel are organic-inorganic structures, and with biochemical findings suggesting that amelogenins are placed in intercrystallite regions and enamelins in crystallite regions. The hypothesis is advanced that enamelins are part of the crystal ghosts of immature enamel.