Anyone ever try these? They are supposedly the best out of the Crest White Strips but you can't get them in stores-- supposedly. I bought mine off eBay as I'm an absolute eBay junky now and I saved a few bucks. But has anyone ever used these? THIS exact kind? I'm sure they must whiten, but are they dangerous? My sister has used the regular kind and her teeth have gotten sensitive. I did a little bit of "google research" but didn't come up with anything other than advertisements. You can get it anywhere online it seems, but just the fact it's the better of the Crest strips, I would assume it's obviously got more potent things on it? I've never tried it before so by going to that one first I just wanted to know what to expect. I can't imagine what sensitive teeth must feel like afterwards, for one thing! How well did they work? I chew so much sugarless whitening gum and use whitening toothpastes, nothing extreme, but my teeth are pretty bright. But I drink a lot of coffee so they are not 100% white and I'm hoping this will get me closer to that.