Excerpt from:

Ramseyer WF, et al. (1957). Effect of Sodium Fluoride Administration on Body Changes in Old Rats. J Gerontol. 12: 14-19.

"The purpose of the present study was to determine the effects of feeding of low levels of sodium fluoride from conception until later life on the animal body in old age. Albino rats were used in this research because their normal span of life is less than two years. Furthermore, the albino rat is considered to have a high tolerance against fluoride toxicity. Therefore, one might expect other species to be affected more adversely than this one.

...The importance of knowledge about the lifetime ingestion of fluorides and their effect upon the diseases of old age is obvious. Hundreds of investigations deal with short-time ingestion of different levels of fluoride, but as far as we have been able to ascertain the literature contains no reports of studies made on a large number of animals and human subjects throughout the whole life span.


The experiments were designed to evaluate 4 levels of sodium fluoride, 0, 1, 5, and 10 PPM fluorine, administered in the drinking water, which had been distilled. A total of 456 albino rats were included in the investigation.


Teeth - Experiment 1: No evidence of caries was found in the 79 animals which were killed at 150 days of age.

The condition of the teeth of the 86 animals that were sacrificed at 520 days of age is shown in table 1. It will be seen from the table that no carious teeth were found in the animals that had not received sodium fluoride supplementation. In contrast to this, a substantial number of the rats in each of the groups that had been given sodium fluoride in the drinking water showed carious lesions of the teeth.

There were no missing teeth in the 520-day-old animals that did not receive sodium fluoride in the drinking water, but a considerable number of teeth were missing among those given the additional fluoride. One rat that had drunk the 5 PPM solution of fluorine had lost 5 molars and another rat that had consumed 10 PPM had lost 6. The data in table 2 illustrate the great individual variability in the reactions to sodium fluoride and the need for large numbers of animals to be used in such research.

No evidence of periodontal disease was found among rats sacrificed at 150 days of age.

Only two cases of periodontal disease were observed among the animals killed at 520 days of age which had not received sodium fluoride supplementation in the drinking water. In contrast to this, there was evidence of periodontal disease in al old animals that had been given sodium fluoride in the drinking water, as shown by alveolar bone destruction and increased porosity of bone. The lesions were as severe in those rats given 5 PPM of fluorine as in the animals receiving the higher level of 10 PPM.


The effects of feeding low levels of sodium fluoride from conception until old age were determined in a total of 456 albino rats. Four levels of sodium fluoride (0, 1, 5, and 10 PPM fluorine) were given to 4 groups of animals in their drinking water. In one study half of the rats were killed at 150 days of age and half at 520 days. In the second experiment all rats were killed at 150 days.

No evidence of injury to teeth was found in the animals killed at 150 days of age, but marked injury was noted in those given sodium fluoride supplementation until they were 520 days old. In old age missing teeth and periodontal disease were frequent in rats which had received sodium fluoride supplementation, especially at the higher levels."

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