Caries is ordinarily an expression of disturbed metabolism, often due to excessive irregularity in diet and mode of living. No diet can prevent caries when metabolism is disturbed. Change in diet, not only food as such, causes caries. A satisfactory monotonous diet—without improvised extra meals—is the only one that prevents caries. The caries-prophylactic effect of symmetric extraction of six-year molars is due to changes in local circulatory conditions, not to improvement of hygienic conditions.
Extraction of a molar in a guinea-pig causes the teeth, after healing of the wound, to become larger on the side operated upon; but if extraction is incomplete,so that regrowth takes place, the opposite effect occurs. Caries is caused, in guinea- pigs, by dietetic change from rich food to food restricted in vitamins and minerals. Extreme caries can be caused, in rats, by variable subcutaneous injections of acid and basic substances.
References: Svensk Tand. Tidskr., 1933; Ann. Anat. Path., 1935 ; Odont. Tidskr., 1936; Pardentium, 1936; Acta Paediat. Scand., 1938.