Whitening toothpastes
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There are many "whitening" toothpastes on the shelves today, but experts say this label can be misleading because the products usually don't remove intrinsic stains. "The so-called whitening toothpastes contain abrasive particles and they may only be effective on stains from food and drink, which get trapped in the surface layers of tooth enamel," says Dr. Gianluca Plotino, a private-practice dentist in Rome.

At most, whitening toothpastes can help remove surface stains over time and prevent new ones from forming. This kind of stain removal may make your teeth appear brighter, but only minimally so, and it may come at a cost. In 2011, researchers found that the most effective whitening toothpastes are generally the most abrasive. Some products, including Crest White Vivid and Ultrabrite Advanced Whitening from Colgate, are so abrasive that they're considered to be potentially damaging to enamel. Prolonged use of these products could wear away your enamel and expose your dentin – depending on the color of your dentin, these highly abrasive toothpastes could, theoretically, make your teeth appear less white.