STUDIES OF THE CAUSE AND NATURE OF DENTAL CARIES

¹ Mellon Institute and School of Dentistry, University of Pittsburgh, Pa.

To summarize briefly the results of these studies of lactobacilli of dental and intestinal origins, the evidence indicates that there are two main types that may be differentiated quite easily by a combination of morphological, fermentation, agglutination, and growth (at 15°C.) characteristics. The Group-I type usually produces a smooth colony, and acid without gas in glucose, galactose, levulose, maltose, lactose, sucrose, mannitol, sorbitol, dextrin, and salicin; does not produce acid or gas in raffinose, arabinose, xylose, or inulin. The strains of this type grow at 15°C., and are agglutinated by an antiserum produced by injection of suspensions of a Group-I organism into a rabbit. The Group-II type produces usually a rough fuzzy type of colony, and acid in glucose, galactose, levulose, maltose, lactose, sucrose, and raffinose; may or may not produce acid in dextrin; usually does not produce acid or gas in arabinose, xylose, mannitol, sorbitol, salicin, or inulin. The strains of this type do not grow at 15°C., nor are they agglutinated by Group-I antiserum. Each of the two main types is found among strains of dental and intestinal origin.