ELECTRON MICROSCOPY OF CARIOUS DENTIN

¹ Department of Basic Science, School of Dentistry, and Department of Experimental Medicine, School of Medicine, University of Southern California, Los Angeles, Calif.

Detailed histologic studies of various dentin with the electron microscope have been undertaken by the use of ultrathin sections. Electron micrographs are presented which demonstrate the different zones of degeneration based on degree of bacterial invasion. The most superficial zone is characterized by complete decalcification and decomposition of the dentin. An area of incipient decalcification in which the bacteria have invaded the tubules is the second zone. In this region, sclerosed tubules are found with their lumina obliterated by either a homogenous or a calcified material. Collagen fibrils of 640 A striations are also evident in this region. In the deepest layer from the area of decalcification, a few tubules contain microorganisms.