Observations on Induced Dental Caries in Rats

Abstract

Epidemiological evidence (1), (2), (3), and experimental studies in rats (4), (5), (6), have shown that the process or processes involved in the production of dental caries can be altered by the presence of fluorine in the drinking water or in the food. It has been suggested that the fluoride ion acts either as an anti-enzymatic agent or produces a more resistant tooth substance; whether this action is local, systemic, or both, is not known. Dean, Jay, Arnold, McClure and Elvove (2) have pointed out that the epidemiological evidence cannot be adequately explained on the presence or absence of dental fluorosis; however, at Bauxite, Arkansas, mottled teeth resisted dental caries attack even though the population had been using a fluoride-free drinking water for the past twelve years (7). Cheyne has interpreted his results (8) to show that the action of fluorine on dental caries in rats was not dependent on the presence of saliva. McClure (9) has shown that the caries resistance of rats is correlated with the amount of fluorine in the diet; also the fluorine content of the molar teeth of these rats changes in direct proportion to the amount of fluorine in the diet. None of this evidence permits conclusions to be made as to whether the action of fluorine on dental caries is local, systemic, or associated with the tooth structure. The present experiment was planned to eliminate the local action of the fluorine so far as it is related to the presence of this element in the food or drinking water. To this end, the fluorine was administered by subcutaneous injections of NaF, and the dental caries experience of the injected rats was compared with that of a control group and a group receiving 10 ppm. F in drinking water.