Caries is due to starch lodgments on enamel. When starch is retained in the mouth, it is deposited on teeth in loosely constructed masses, and bacteria of caries become abundant and active. In a starch-free mouth, there may be a small number of inactive bacteria. B. acidophilus cannot be successfully implanted in a starch-free mouth. Salivary ptyalin, when in normal quality, clears the mouth of starch debris. Without starch lodgment there can be no caries, excepting ” sugar caries “—to which there is no immunity. Sugar in solution in saliva cannot lodge on a tooth, and there locate a cavity, as does starch. Acid-forming foods predispose to caries by depleting the alkali reserve, which in turn causes retention of carbon dioxide, in the salivary glands. These glands are small, and the secretion of a normal amount of saliva, with its essential ptyalin in the brief period of a meal, requires great activity. When in active secretion, these glands require a large amount of oxygen, and a correspondingly large amount of CO, is formed. With normal reserves there is no difficulty; but, when the reserves to clear the tissues and cells of CO, are depleted, congestion ensues, and there is loss of ability to secrete ptyalin.
Caries is a mild scurvy or an exact parallel, as it is caused and cured by the same foods and has the same pathological symptoms. This is the pathology of a ” plus metabolism,” which is an acidosis. A ” plus metabolism ” causes congestion of the gums, which results in proximal and cervical carious cavities. A ” minus metabolism,” which is an alkalosis—by inhibiting enzyme actions and digestion by ptyalin—causes susceptibility to caries through failure of ptyalin to prevent starch lodgment.
References: Den. Items Int., 1937, 1938.