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Show Here's How to Find Out if Dentifrice Hurts Your Teeth Uncle Sam Tests 2. Rramls in Placing Order Atlantic City. With n nickel nick-el and a piece of glass you can make a simple test that will tell you whether your favorite fa-vorite toothpaste will scratch the enamel of your teeth. The test is one that the United States government requires for all toothpaste purchased and it was described de-scribed at the meeting of the American Amer-ican Dental association here by Drs. Wilmer Souder, physicist, and Irl C. Schoonover, chemist, of the national na-tional bureau of standards. Uncle Sain buys large quantities of toothpaste. When an order for some 14.000 dozen tubes was contemplated, con-templated, a committee was appointed ap-pointed to write specifications for a safe and etTective cleanser for ttie teeth. These specifications, now adopted for use, were reported here. Must Not Contain Tolson! Safety for the tissues of the mouth and the teeth was the first consideration consid-eration of these men when they met to decide what must be contained in Uncle Sam's toothpaste. Next came i the question of efficiency in removing remov-ing foreign materials from the matter of flavor or perfume. A toothpaste must not be excessively exces-sively either alkaline or acid. It was decided. It must not be caustic. It must not contain arsenic or other poisons. It must have a preservative preserva-tive that will insure that it keeps In good condition until used. Twenty-five popular brands of toothpaste were tested against the specifications as adopted for use in ! government purchasing. More than half failed to meet the requirements, require-ments, Drs. Souder and Schoonover said. Hardening, separation of ingredients, in-gredients, and fermentation or spoiling spoil-ing were the most common faults. Some showed signs of chemical attack at-tack upon the tube container, and that was considered undesirable. How to Make Test. Ten toothpastes among those tested test-ed failed on the test for scratching. This test as developed at the national na-tional bureau of standards, can ba used by anyone who wants to be sure his dentifrice Is not scratching scratch-ing the enamel of his teeth. A piece of glass and a piece of alloy metal of the size and hardness of a five-cent five-cent piece are all that are needed for the experiment First test the glass for hardness by rubbing the edge of the metal piece over it to be sure that the metal alone does not scratch the glass. Human enamel and glass both vary in hardness. hard-ness. Place some of the toothpaste to be tested on the glass and rub again with the coin. If scratches result, then you may expect scratches on your teeth. This test is sensitive enough to detect one part of emery in one thousand parts of paste. |