Postdevelopmental effects of boron, fluoride, and their combination on dental caries activity in the rat

Drinking water of rats aged 21 days was supplemented with 1, 10, 30, 50, 100, or 283 ppm of boron or 10 or 25 ppm of fluoride individually or in combination. All rats were fed a cariogenic diet. Boron did not reduce dental caries activity in erupted molars after eight weeks. When given in combination, it partially antagonized the cariostatic effect of fluoride.