I tried Crest strips about a year and a half ago after my friend swore by them. Her teeth were definitely whiter, but I still didn't know if they'd work that well. They are a little expensive, so I didn't want to just waste the money if they weren't going to work. I researched them a little and compared them with other brands, and found that a lot of people liked them. I figured I'd give them a try. After about 1 week (out of 2) I definitely noticed whiter teeth, and so did other people (family & friends that saw me often). I was definitely very happy with the results. Even now (1 1/2 years later),...