The Effect of the Feeding of Fluorides upon the Chemical Composition of the Teeth and Bones of Albino Rats

The toxic effect of fluorides upon the teeth and bones of animals has been demonstrated. In 1925 McCollum, Simmonds, Becker, and Bunting (1)) also Schulz and Lamb (2)) reported a disturbance in the quality and structure of the teet,h of albino rats, produced by amounts of fluorides only slightly above that occurring in natural foods. Since then the observed harmful effects of the feeding of rock phosphate as the source of calcium and phosphorus to various animals (3-7) has been related to its fluorine content by Tolle and Maynard, 1928 (5), Taylor, 1929 (6), and Bethke, Kick, Edgington, and Wilder, 1929 (7). More recently the writers (8, 9) have shown that the presence of low concentrations of fluorides in drinking water is the cause of the peculiar human dental defect known as “mottled enamel” which occurs in many parts of the world. A defect similar if not identical in characteristics has been produced in rats, in guinea pigs, and in dogs (10) by the feeding or injection of fluorides. As a result of the feeding of fluorides, the teeth not only lose the pigment and translucency normal to them, becoming dull and chalky white in appearance, but the enamel corrodes and chips off. Over longer periods of feeding there is a marked tendency to overgrowth or excessive wearing down of the incisors of rats. The severity of t,he defect is in proportion to the amount of fluorine fed. All of these changes indicate alterations in the tooth structure and composition. Some work has been done to determine the nature of the changes.