A METHOD FOR LIGHT-MICROSCOPY EXAMINATION OF CELLULAR AND STRUCTURAL INTERRELATIONS IN UNDEMINERALIZED TOOTH SPECIMENS

This study examines ameloblasts and odontoblasts in relation to minera lizing enamel and dentin in thin undemineralized tooth sections from u nerupted and partly erupted human third molars. The material comprised 12 freshly removed third molars. After fixation for 24 h the specimen s were dehydrated and embedded in hydroxyethylmethacrylate. Undeminera lized sections 10-15 mum thick were prepared with a cutting-grinding s ystem, and radiomicrographs were taken. Postsecretory ameloblasts were seen in different morphologic stages ranging from ruffle- and smooth- ended ameloblasts to cuboidal and squamous cells adhering to incomplet e and fully mineralized enamel. The former occurred in the most corona l tooth part, whereas the latter were seen cervically. It was not poss ible to identify systematic modulation cycles as seen in postsecretory rat incisor ameloblasts. The well-defined subodontoblastic region wit h cell-free and cell-rich layers was established before tooth eruption . The function of the subodontoblastic region is not fully understood, but our findings suggest that the establishment of the region plays a role in maintaining the specific odontoblast phenotype in the coronal region possibly linked to progressive dentin mineralization.