Review (5/5): Starts brighter, then gets whiter
Got these for my husband. He has perfectly aligned teeth (naturally) and has never had a cavity. However, we were starting to call his teeth his "pearly yellows." I guess he drinks too much espresso.
Anyhow, we bought the classic strips because of the lower level of peroxide - he is sensitive to stronger amounts (it makes his gums hurt). Within the first 2 days we saw his teeth starting to look brighter, but not really whiter. It wasn't until around the 5th day that we could say, "wow" - this stuff is really working. He didn't even need the full 2 weeks - his teeth are quite white now. He uses the remaining strips once per week to maintain the whiteness.