The rôle of B. acidophilus in dental caries.

Abstract

Since the first pronouncement by Miller 1 in 1890 that tooth caries is the result of the acid fermentation of carbohydrates by bacteria, students of this subject have been searching for a specific organism of caries.

Kligler 2 first pointed out that in the lesions of caries B. acidophilus is commonly present, associated with L. buccalis, C. placoides, and B. putrificus. Later Howe and Hatch 3 found in advanced lesions of caries the Moro-Tissier group of organisms associated with certain other types which they called respectively Bacillus X, M, and Y. More recently MacIntosh, James and Lazarus-Barlow^4,5 in England, and Rodriguez 6 in this country, by the use of acid media have found that in deep carious lesions B. acidophilus is invariably present and is the most predominant acid-resistant organism associated with the disease. They were also able to produce caries-like lesions in teeth which were immersed in cultures of B. acidophilus.

During the past year, in our study of the cause and means of preventing dental caries, we have devoted our attention to a study of the initial stages of caries and the bacteria found to be associated with the first lesion, on the tooth. In a study of 73 cases, we found B. acidophilus present in 100 per cent of initial caries, in 94 per cent of advanced caries, and in 16 per cent of mouths that were immune to caries, In carious mouths this organism exhibited a high degree of proliferation and a tendency to localize on the tooth, but when present in caries-immune mouths it did not appear to grow in concentrated niasses, nor did it predominate in the oral flora as was the case in, carious individuals.

We found further that caries-like lesions of the tooth may be produced artificially by lactic acid solutions in concentrations below pH 4.4, in 11 days; also by different strains of B. acidophilus in glucose media in from 6 to 8 days when the action was confined to a limited area of the tooth.