"The toothbrush, in various forms, has long been well-regarded as the best tool for a healthy mouth. What to use with it, however, is a more complicated, at times toxic, tale.
The first recorded suggestion is from fourth-century Egypt, when a scribe wrote that a mixture of rock salt, mint, dried iris flower, and pepper formed a "powder for white and perfect teeth." Concoctions in the centuries since often included crushed coral or volcanic rock. These powders removed stains and tooth enamel equally well. Soap-based pastes replaced powders in the late nineteenth century, though with little improvement. Columbia University chemist William Giles, an early-twentieth-century researcher, described the pastes as "hard and sharp enough to cut glass." One 1930s product, Tartaroff, contained 1.2 percent hydrochloric acid; a single application could destroy 3 percent of a tooth's enamel, according to James Wynbrandt's Excruciating History of Dentistry."
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