They definitely work. I have used many whitening products and they work as well as most of them. I think crest whitening strips are faster, but they're a lot cheaper, so they're worth it. I got my teeth pretty white with a comb, but I kept them with it for about a year. If you have trouble moving the gel over the strip, refrigerate until ready to use. They cause sensitivity, but I've never used a whitening product that doesn't.
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