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

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

1. The incidence of caries and the attack rate the following year were much higher in the Boulder group where no fluoride was present in the water than in the Denver group where there was 1 ppm fluoride.

2. There does not appear to be any appreciable difference in the relative proportion of any given fermentative type of lactobacillus in the area with fluoride and the area without fluoride.

3. The incidence of caries was higher in children who had high lactobacillus counts than in those with low counts, and higher in those with Type I lactobacilli in their saliva than in those with other types.

4. (a) In the children whose drinking water contained no fluoride, the number of carious surfaces and the per cent of those with caries, was much higher in the group with low lactobacillus counts when Type I was present. These values were higher, but less so, in the group with high counts when Type I was present.

(b) In the children whose drinking water contained 1 ppm fluoride, the number of carious surfaces and the percentage of those with caries was slightly higher only in the group with high lactobacillus counts when Type I was present.

5. The possible significance of these findings was discussed.