This section is from the book "The Hygienic System: Fasting And Sun Bathing", by Herbert M. Shelton. Also available from Amazon: The Hygienic System Vol III Fasting and Sun Bathing.
Teeth are specialized bones and are subject to the same laws of nutrition as other bones of the body. In certain quarters it is claimed that fasting ruins the teeth. The claim is not true and no one with a knowledge of fasting makes it. No evidence exists that there is any loss to the bones or teeth during a fast. There is an apparent decrease in the amount of organic matter in the teeth of starved rabbits, but the teeth of these animals grow continuously throughout life, and Prof. Morgulis suggests that this decrease may be due simply to a deficiency of building material.
Jackson says: "Like the skeleton, the teeth appear very resistant to inanition. * * * In total inanition, or on water alone, the teeth in adults show no appreciable change in weight or structure."
There is no truth in the notion that fasting injures the teeth. On the contrary, repeated tests and experiments in the laboratory have shown that the bones and teeth are uninjured by prolonged fasting.
I have conducted thousands of fasts and I have never seen any injury accrue to the teeth therefrom. No one makes a trip to the dentist after a fast who would not have gone there had the fast not been taken. Mr. Pearson records that at the end of his fast, "teeth with black cavities became white and clear, all decay seemed to be arrested by the fast, and there was no more tooth-ache."
The only effects upon the teeth which I have observed to occur during a fast are improvements. I have seen teeth that were loose in their sockets become firmly fixed while fasting. I have seen diseased gums heal up while fasting. But I have never, at any time, observed any injurious effects upon the teeth during or after a fast, regardless of the age of the faster and the duration of the fast. This applies only to good teeth. Fasting does sometimes cause fillings to become loose.
Although I have always regarded the loosening of fillings in teeth as due to the extraction of the salts of the bad teeth, some of my students have brought up the question: Is the loss of the filling due to an effort of Nature to dislodge a foreign body preparatory to healing the tooth? This question is worthy of study.