Light and Electron Microscope Evaluation of Changes Induced in Odontoblasts of the Rat Incisor by the High-Speed Drill

¹ Department of Anatomy, College of Medicine, University of Iowa, Iowa City, Iowa

The present study has established the normal fine structural appearances of the rat odontoblast; the effects of the high-speed drill on this cell type have been studied. The normal odontoblast presented four distinct histologic zones which indicated a physiologic polarity to the cell. The morphologic changes seen in the odontoblast were thought to be the result primarily of protein denaturation that occurred after the experimental procedure. The possible causative factors appeared to be heat, resulting from lack of effective cooling or from friction from manual pressure, and mechanical vibration. The morphologic changes, in some cells, proceeded to destruction, which necessitated replacement. No mitotic activity occurred in the odontoblastic layer, and it is suggested that replacement was a result of differentiation of undifferentiated pulpal cells; however, no direct evidence was obtained to support this view.