THE RELATION OF CARIES ACTIVITY TO LACTOBACILLUS COUNTS AND TYPES AND TO THE FLUORIDE CONTENT OF DRINKING WATER

II. RESULTS OF EXAMINATIONS MADE AFTER A ONE-YEAR INTERVAL

¹ Department of Microbiology, University of Colorado School of Medicine, and the Colorado Department of Public Health, Denver, Colo.

Suggestive evidence has been presented that when children whose drinking water contained 1 ppm fluoride had large numbers of rhamnose-fermenting lactobacilli in their saliva, they were more likely to have increased caries the year following this examination, When there was no fluoride in the water, nearly all of the children had increased caries, regardless of numbers and types of lactobacilli.

The finding of large numbers of lactobacilli in the saliva, of any type, was usually associated with a rise in the number of decayed surfaces. Bacterial flora of the saliva of this age group varied considerably from one year to the next, both qualitatively and quantitatively. Fluoride in the drinking water in a concentration of 1 ppm appeared to have no effect on the type of lactobacillus which may become established.