I scheduled an appointment for a 40 minute whitening. The advertisement said there would be a significant difference after a 40 minute session. However, once there I got a totally different story. The gel that they use is only 12% strength where a dentist uses 40 to 50%. I was told it would take multiple sessions to get to the brilliant white that they have advertised. My teeth aren't that horrible but when she showed me the color change after a 40 minute session it wasn't much of a difference from the original. I was super disappointed. It's my opinion that this service is for people that may have already been treated somewhere else and are just needing touch ups.