Saliva-glucose-human-enamel mixtures, incubated for four hours in a body- temperature water-bath, present reliable indices of caries activity or quiescence. When calcium and phosphorus are dissolved from the enamel in significant amounts, during this four-hour period, activity is indicated in proportion to the amount dissolved. If very little or no mineral is dissolved, the person from whom the saliva was obtained is immune, or the process is inactive. This test serves as an accurate yardstick for evaluation within a short time of methods which may be used to control susceptibility. Efforts to control caries, in the Caries Clinic and in groups (as in children’s homes), are being measured by routine use of this test. Some degree of success has been achieved in individuals and groups by reduction in the intake of sugar especially, and of starch, and by other modifications of diet. Some methods have been found ineffective, such as supplementary administration of vitamin D with calcium salts. Four-hour incubations of experimental glucosesaliva-enamel mixtures, in which the bacterial content of the saliva is under control, indicate that no one organism (bacteria, yeast, etc.) in the mixture causes enamel decalcification at a speed at all comparable with that of saliva from a susceptible person. But speedy decalcification is brought about by suitable combinations of organisms. An experiment by our nutritional advisor, on a small group of children in which caries has been completely absent up to the age of ten years, was conducted to determine which foods and their amounts would be chosen by these children from a large assortment of cooked or raw, uncombined, unseasoned, and unsophisticated foods. Free sugar was excluded ; sea salt was substituted for ordinary table salt ; no food was permitted between meals. Two of the original subjects have been under constant, adequate observation ; they not only have been completely free from caries but also have retained the same diet pattern developed during the experimental period. These diets are characterized by high vitamin, high mineral and high protein components–carbohydrates quite low ; the foods are natural rather than highly refined ; free sugar is nearly absent—conditions that are comparable with those in the localized groups in which caries is low : Eskimos, South Sea Islanders and others.
The clinical activities of this group of workers are conducted through the medium of weekly caries clinics, at which patients are thoroughly examined, tests made, and individual programs devised for experimental management of each case. The work includes basic studies related to perfection and comparison of chemical and bacteriological tests of saliva, with reference to caries susceptibility ; to mechanism of the carious process ; organisms that may be involved; enzyme action of these organisms and relative effects of the enzymes on various carbohydrates ; production of artificial bacterial and mucous plaques, and their effects on underlying teeth in vitro.
References: Am. J. Dis. Child. (Davis), 1928, 1933; Northw. Univ. Den. Res. Grad. Study Quart., 1937 ; Black’s Operative dentistry, 7th ed., vol. 1, pp. 147, 148, 168; 1936.