just a quick note for anyone wondering about crest tooth whitening strips. i tried them while in america and have since bought them from ebay. my teeth were realy yellow and i debated  paying the hundreds my dentist wanted to whiten them, but now i dont have to the strips are realy easy to use and they realy work. i have tried many other products on the market with no success, but be careful because there are many differnt strengths get a premium plus or more if you have a lot of yellowing. good luck