Early cellular changes in pulps whose blood supplies were severed were studied using transmission electron microscopy (TEM). Twenty-eight extracted teeth were divided into seven equal groups. Except for the 0 hour group, all other teeth were incubated in Tyrode solution at 37°C, after extraction. After 1/4, 1/2, 1, 2, 4, and 8 hours, teeth were split open and the pulps were processed for light and transmission electron microscopy and evaluated for cellular changes. Except for nuclear pyknosis in the 4 and 8 hour groups, light microscopic examination revealed very little changes when compared with that of TEM examination. With the TEM, the first cells which showed changes were the odontoblasts and the most resistant structures to show changes were the unmyelinated axons. Changes observed in the nuclei included chromatin clumping, pyknosis and polarization of the nucleoli to the periphery. Cytoplasmic changes observed were mitochondrial swelling, dilatation of endoplasmic reticulum, increased vacuolization, and increased presence of lipofuscin and lipid inclusion bodies. Further, plasma membrane distortion, degeneration and fragmentation were also seen. Nuclear changes usually preceded cytoplasmic changes. Other observations were that endothelial cells showed a decrease in micropinocytosis and an increase in cytoplasmic protrusions. Nerve fibers exhibited degenerative changes in the myelin sheaths and a loss of microtubules in their axons. It was not possible to pinpoint in any of the cell types examined a specific time at which the transition from reversible to irreversible condition occurred.
Leif K. Bakland
James H. Simon
Master of Science (MS)
Year Degree Awarded
Date (Title Page)
Library of Congress/MESH Subject Headings
Dental Pulp -- injuries; Dental Pulp -- blood supply; Microscopy, Electron
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Chen, Nah Nah, "A Transmission Electron Microscopy Study of Early Changes in Hypoxic Pulps" (1987). Loma Linda University Electronic Theses, Dissertations & Projects. 1276.
Loma Linda University Electronic Theses and Dissertations
Loma Linda University. Del E. Webb Memorial Library. University Archives