Whenever I whitened my teeth (using the dental trays from my dentist), it never lasted very long, probably because I'm such a coffee addict. I got discouraged and gave up. My hygenist told me to just buy a Sonicare toothbrush and use it with Rembrandt toothpaste, which I did, and my teeth looked much better. Then I discovered this toothpaste called Supersmile. It's a bit pricey, but since I've been using Supersmile (with the accompanying "accelerator") with the Sonicare brush, I'm not embarassed to smile anymore. No, my teeth are not as bright as they were when I used the trays, but they do look noticeably better, and, most of all, it's consistent.