Can someone tell me all about teeth whitening strips please?

Are they good for your teeth? Will they damage them? Are they expensive for good ones? How do they work? Thank you! :)
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No but they aren't permanant, you need to do it every few months depending on your eating habits. Also it's bad if you swallow them so be careful :P from my experience I only had a TINY whitening effect... barely even visible to my friends. They were good ones too, did it for like a month. You should go for something else in my opinion.
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