I love Crest White Strips, they work amazingly! I had last whitened 6 months ago, right after my teeth cleaning and this last cleaning my hygienist complimented how white my teeth are and she was blown away that it had lasted for 6 months. I just had the cleaning so now I'm whitening again, it's now my ritual. Being a smoker and coffee drinker, you would never know it by my smile!