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My dentist says that dental enamel is never replenished and we have to make do with the adult set of teeth throughout our grown-up lives. I can’t believe that after some 80 years of chomping and grinding, my teeth are still the same shape, without apparent signs of wear. Is he right? If so, why am I generally still toothily intact?

John Everest, Pinner, Middlesex, UK

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This article appeared in print under the headline “Long in the tooth”