[Research in Germany and Switzerland, 1932-37.]
Incidence and progress of caries, and film and tartar formation, increase as degree of mastication decreases. Thin hard-bread products, made of coarsely ground whole-grain—which require vigorous mastication, stimulate salivary secretion, and increase pH and alkali concentration—prevent (a) onset or (b) progress of caries, and also (c) formation of film and tartar. Such hard-bread products promote tooth formation, and also increase body weight and height.
For production of flour to be used for hard-bread products, clean grain should be thoroughly ground to include all parts, at a temperature (external and in the machinery) below 50° C., to prevent destruction of thermolabile elements. Removal of germ and brain eliminates important nutritive ingredients, including fluorine needed for tooth development. The amino-acid lysin—of which the bran contains ten times more than the amount in the rest of the grain—is specially important for development of muscle. The dough should be neutralized to remove surplus of phosphoric acid.
Effects of alternate feeding of bread-products of known character and composition were studied in Germany and Switzerland in numerous separate experiments and tests during a period of 27 to 46 months (1932-37). Two groups of 20 children each (ages 4 to 12 years) were observed continuously under the same living and dietary conditions, the only difference being that one group was always given 80 or 83-percent ordinary ryebread, baked uniformly at the usual high temperature in loaf form (soft interior and solid crust) ; the other group received whole-rye bread in the form of hard flat cakes (” Knackebrot “) from flour and dough prepared as indicated above, baked quickly, dried promptly, and given in five periods of different lengths. These five periods of feeding for the hard-bread group differed either in the hardness of the bread ; addition of 83-percent soft rye- bread ; or addition of hard fruits. The average age of the first (soft-bread) group was one year more than that of the second (hard-bread) group. Initiation and progress of caries, formation of dental film and tartar, also pH and alkali concentrations in saliva, muscular growth, height, weight, and power of mastication, were favorably influenced by hard-bread made from ground whole-rye. Using 100 to represent conveniently the caries in the hard-bread group, the caries in the soft- bread group increased to 289 in deciduous teeth and to 143 in permanent teeth. Under the influence of soft-bread feeding, caries developed twice as quickly in the deciduous teeth, and was 1.5 to 3 times more abundant. The average power of mastication of the hard-bread group was 40 percent higher than that of the soft- bread group. Salivas of ” hard-bread children ” showed these increases : 40 percent in secretion, 90 percent in pH, 30 percent in alkali concentration. These children also showed increases of 51 percent in body height, and 52 percent in body weight, over those of the soft-bread group.
References: Forrog-Bliitter (Zahnitrz. Mitteil.), 1934; Trans. IXth Intern. Den. Cong., 1936; Kampf d. Karies (Zahndrz. Mitteil.), 1937.