I think I saw an ad for Opalescence in a recent magazine. Anyways, I knew my teeth needed some heavy-duty whitening so I decided to try it. All I have to say is – IT WORKS! After two days of use there was visible improvement. After a few more days my teeth are as white as they would be after going to the dentist and paying for a $500 whitening procedure. Luckily I already had custom trays for my teeth so I just bought the Opalescence 15% syringes and used my trays. The whitening gel cost around $20. An absolute steal.