I was very excited to try this product. I don't have severely stained teeth; however, they certainly showed that I am a coffee and black tea drinker. I followed the instructions exactly as they were listed, but in the end I didn't see the results the packing claimed I would see. I definitely did not get my money's worth. Also, I found that using it was pretty awkward and didn't make it easy to do much else during the entire hour. I only gave this a C grade because it may be better suited for people with darker stains - I'm not sure.