Oral flora of children with "nursing bottle caries".

S. mutans averaged about 60% of the total cultivable flora of dental plaque obtained from caries lesions, white spot margins of these lesions, or clinically-sound areas of upper anterior teeth, and averaged about 27% in plaque from mostly clinically-sound areas of posterior teeth of six children with nursing bottle caries; its concentrations in saliva averaged about 10% of the total cultivable flora. Nearly all of 107 isolated S. mutans strains belonged to the serotype group c/e/f. The proportion of S. sanguis, in contrast to those of S. mutans, were very low in plaque from upper anterior teeth and higher in plaque from posterior teeth. The proportions of S. salivarius in saliva were unusually low, and this organism was not detected in the saliva of most subjects. Lactobacilli were found in nearly all plaque samples; plaque and carious material from cavities contained higher levels than plaque associated with white spots or clinically-sound tooth surfaces. The findings provide further support for the role of S. mutans in the initiation of human dental caries. In the case of lactobacilli, they support other evidence suggesting only the limited involvement of these organisms in the initiation of caries lesions, but a more extensive role in their progression. In addition, they clearly illustrate the marked effect of diet on the dental plaque flora.