L.T.
Hi R.,
I tried the "Crest Whitestrips Renewal-Age Defying Strips". This product was on sale at Walgreens and guaranteed whiter teeth in 10 days or your money back! I bought this item about a month ago and I honestly noticed a difference on the second day, it did work for me. My teeth were clear and whiter (others noticed too). However, I did experience sensitivity after using it on the 4th day. I continued using the product, but only once a day for 30 (mins) instead of twice a day as instructed. I would use it again if I need to since I seen the results and I also like the money back guarantee if it does not work!
Hope this helps!
Mom of 1 in Westchester