Before considering any tooth-whitening agent, says Christine Dumas, D.D.S., you'll want your dentist to see if any of your teeth are cracked, you have cavities, or your gums have receded, exposing roots (if you dab tooth-whitening paste onto a naked root, your loved ones will have to peel you off the ceiling). Also, if you have crowns or two-color fillings, you could end up with teeth of various shades—hardly that fresh-faced, surfer-girl look you had in mind.
Bottom line: For a completely safe whitening, let your dentist do it.
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