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Scientists in Germany used x-ray photoelectron spectroscopy to get a detailed image of the surface of a considered tooth. And they found that the protective covering is ponderously only 6 competences thick. That’s about a fifteen-thousandth as thick as a sheet of form. And a layer that skimpy would likely be worn away by specific chewing. How fluoride keeps the tooth fairy away is a mystery that teacupful are still working to unravel.