Dentinal tubules have generally been considered to be occupied only by the cytoplasmic processes of odontoblasts. Recently, however, JOHANSEN and PARKS [1] and FRANK [2] found unmineralized collagen fibers along with the odontoblastic process in dentinal tubules. JAMES [3] failed to find odontoblastic processes in the peripheral parts of the dentinal tubules in his histochemical study and this was confirmed by BRÄNNSTRÖM and GARBEROGLIO [4]. According to FURSETH and MJÖR [5], only an amorphous substance and collagen fibrils were observed in the obturated dentinal tubules in the cortico-steroid covered dentin. Based on these reported studies, there could be a relationship between the appearance of collagen fibers in the dentinal tubule and disappearance of the cytoplasmic process.
The present report deals with the intratubular structures observed in the dentinal tubules with a scanning electron microscope.