| 31. | This phenomenon is known as " stress whitening ".
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| 32. | Some of these bleaching products and whitening toothpastes can harm more than they help.
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| 33. | John Major's whitening haircut doesn't quite make him King Lear.
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| 34. | There's no question that whitening is a lucrative side business for dentists.
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| 35. | Slightly less serious is professional teeth-whitening.
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| 36. | We put the whitening strips to the test with the help of six people.
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| 37. | How it works : Soft rubber tooth guard trays are filled with whitening gel.
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| 38. | The whitening agent is usually carbamide peroxide or hydrogen peroxide, and strength varies.
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| 39. | Among those identified are advertisements promoting liquor, slimming and skin-whitening products.
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| 40. | They are said to provide lasting whitening care.
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