Francis A. Arnold

Studies on mass control of dental caries through fluoridation of the public water supply.

Numerous epidemiological studies (1) conducted in widely separated parts of the world clearly demonstrate that the use of fluoride drinking water during the formative period of the teeth is associated with a 60to 65-percent reduction in dental caries experience. This inverse relationship between dental caries prevalence and fluorides in drinking water approaches its maximum at a fluoride (F) concentration of 1.0 to 1.5 ppm., a concentration which Dean (2) established as the minimum threshold concentration of mottled enamel or endemic fluorosis. These findings led to the proposal that optimum amounts of fluorides be -added to the drinking water supply as a partial caries-control measure. The proposal engendered extensive field and laboratory studies on the physiological effects of fluoride ingestion (1). The results of these studies indicated that not only was 1.0 ppm. in the drinking water an optimal concentration for caries control but well within the limits of safety. In 1945, three studies to determine the caries prophylactic value of artificially fluoridated drinking water were started in the United States and Canada. A number of additional study projects have been initiated in the United States since that time. One of the studies started in 1945, that in Grand Rapids, Mich., serves as the basis for this preliminary report.

The effect on caries incidence of a single topical application of a fluoride solution to the teeth of young adult males of a military population.

Epidemiological evidence shows that individuals using, throughout life, domestic waters containing small amounts of fluoride experience a relatively low amount of dental caries. Some of the epidemiological aspects of the fluorinedental caries relationship have been recently reviewed by Dean (1). In order to test further the inhibitory effects of fluorides on dental caries other avenues of approach are being investigated. Results of studies designed to determine whether or not fluoride solutions applied to the external surfaces of the teeth would decrease their susceptibility to caries attack have been reported (2), (3), (4). While these studies are still in the experimental stage, the results have suggested a beneficial effect. The three studies reported were made on children and multiple applications of fluoride solutions were used during the study period. The primary purpose of this study was to learn whether or not a single application of a fluoride solution would appreciably lower the incidence of dental caries in young male adults living under military conditions. If multiple applications were necessary to decrease the caries incidence, the value of this prophylaxis would be largely nullified insofar as its use in the armed forces is concerned.2 The present study was made at the U. S. Coast Guard Academy, New London, Connecticut. All regular Cadets of the 2nd and 3rd classes were included in the study and the period of observation was one year. All Cadets ate in the regular Academy Cadet mess.

Observations on Induced Dental Caries in Rats: I. Reduction by Fluorides and Iodoacetic Acid

The communal water supply at Galesburg, Illinois, as compared with that of Quincy, Illinois, was shown to have a marked beneficial effect in inhibiting human dental caries (1). This finding based on epidemiological evidence was tested experimentally by studying the effects of these two drinking waters on induced caries in rats. The results obtained thus far have proved inadequate to warrant definite conclusions, but the data is none the less useful to call attention to what may be an important factor in the problem of induced caries in rats, namely, a possible litter association as to caries susceptibility existing among experimental rats. Other data in this paper, which is the first of a series of papers reporting some recent observations on rat caries made at the National Institute of Health, relate to the effect of: (a) 2 ppm.3 of fluorine as sodium fluoride in the drinking water; (b) 125 ppm. of fluorine as sodium fluoride in the drinking water; (c) 125 ppm. of fluorine as sodium fluoride in the ration, and (d) 200 ppm. of iodoacetic acid in the ration, together with 20 ppm. of iodoacetic acid in the drinking water. Miller (2) reported the prevention of induced caries in rats by feeding fluorides and iodoacetic acid. His results with respect to fluorides were confirmed by Finn and Hodge (3). Cox, Matuschak, Dixon, Dodds and Walker (4) sought to show a reduced incidence of caries in rats due to fluorides contributed to the offspring by mother rats during gestation and lactation. The first production of carious-like lesions in rats molar teeth is

Observations on Induced Dental Caries in Rats II. The Effect of Subcutaneous Injection of Fluoride

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.