A Progress Report on the Bacteriologic Aspect of the Caries Research Program, College of Dentistry, University of California

Abstract

Attempts to isolate organisms from microscopic carious lesions indicated that this was not a promising method for determining the primary etiologic organism of caries. In the present study, tests are being made on the ability of various oral bacteria to produce microscopic carious lesions in unerupted hamster molars in vitro. Bacteria not common among the oral flora are being used as controls. Histologic examinations of 20 molars testing the oral actinomycetes and lactobacilli are now complete. Broth cultures of both the lactobacilli and the actinomycetes have produced microscopic caries-like lesions at a neutral pH. Dextrose broth cultures of lactobacilli which had a terminal pH of 3.5-4 caused a complete dissolution of the enamel and a resultant histopathologic picture totally unrelated to caries. These results suggest that the cariogenic properties of the lactobacilli may not be related solely to their acidogenic properties, and that caries may result from the action of more than one type of organism.