Dr C.L. Drain noticed something highly unusual. The year was 1927. During routine dental examination of hospital patients he discovered the complete arrest and healing of cavities in 28 children. Teeth containing large cavities, which ordinarily would have an area of softened dentin surrounding the zone of destruction, were found instead to be very dense. Open cavities showed no signs of progress months after they were first observed. And some teeth showing unquestionable arrest of cavities were found in the most poorly kept mouths.
When these dental observations were cross-checked with the patients’ histories, it was found that without exception the children with arrested caries were all diabetic patients under the care of Dr J.D. Boyd. Diet, together with minimal insulin, was being used successfully to control the children’s condition. The children were fed a diet in which fat, rather than carbohydrate, was used as the chief source of energy. To a large extent it consisted of milk, cream, butter, eggs, meat, cod liver oil, bulky vegetables and fruit. The daily menu included approximately one quart of milk and cream. The fat was furnished principally as cream, butter and egg yolk. The diet contained no sugar, bread or cereal grains.
For the children following this diet for two months or longer, in every instance the decay was arrested. Soft decaying dentin changed to one “of stony hardness”, with no advance in the destructive process.
Julian D. Boyd, M.D. and C. L. Drain, D.D.S., 1928: The Arrest of Dental Caries in Childhood. J Am Med Assoc. 1928; 90(23):1867-1869. [Link]