Crest Whitestrips is a type of tooth whitening product. A strip of flexible material is coated on one side with a peroxide-based gel that bleaches dark stains on your teeth. Tooth whitening is a continuous process; your teeth may appear brighter after several treatments, but to maintain the whiteness, you'll need to touch up your color with additional applications of Crest Whitestrips. You may also develop some temporary side effects when using this product.
The Crest 3D White website, a consumer information resource about their whitestrip products, explains that you might see white spots on your teeth right after you remove the strips. This discoloration from the bleaching agent is temporary and resolves itself without any treatment within a few hours.
One of the possible side effects associated with Crest Whitestrips and other tooth whitening systems is sore gum tissue. The American Dental Association calls this phenomenon "gingival irritation" and states that the discomfort is more likely in tray-based whitening products than in strip-based tooth bleaching agents. Proctor and Gamble, the manufacturer of Crest Whitestrips reports that you're more likely to suffer from sore gums if you've left the product on your teeth for more time than is directed. This particular side effect is temporary, but may linger until you discontinue use of Crest Whitestrips, according to the ADA.
Tooth sensitivity--the pain you feel when your teeth come in contact with extreme temperatures on either end of the spectrum, or when eating sweet foods--is another possible adverse reaction associated with Crest Whitestrips. You're more likely to suffer from sensitivity early during your treatment process, according to the ADA, yet the discomfort can occur at any time during the extended whitening process. After concluding treatment with Crest Whitestrips, you may find that your teeth are no longer as sensitive.