INHIBITORY EFFECT OF FLUORIDE ON TOOTH DECALCIFICATION BY CITRATE AND LACTATE IN VIVO

¹ National Institute of Dental Research, National Institutes of Health, Bethesda, Md.

1. In rats' molar teeth, 2.5 ppm fluorine gave maximum protection against erosion by lactate at pH 4.5, and 5 ppm fluorine afforded maximum protection against erosion by citrate at pH 6.3 to 6.5. As little as 1 ppm fluorine is effective in significantly reducing the erosion produced by lactate at pH 4.5 and by citrate at 6.3 to 6.5. A minimum concentration of fluoride exists, beyond which further increases in administered fluorine afford no further protection against dental erosion in rats.

2. Fluorine acquired by intraperitoneal injection appeared to be effective in reducing the erosion produced by citrate. However, more than twenty-five times more fluorine was necessary to give the same effect produced by 1 ppm fluorine orally administered.

3. Fluorine injected intraperitoneally was ineffective in reducing the amount of erosion produced by lactate.