I had Britesmile done about three years ago. It took longer than one hour. I was able to wear these glasses that showed me a movie, so it was more like 2.5 hours
It became somewhat sensitive during the Britesmile treatment, somewhat like little sharp jabs of your nerves. Typical of this type of treatment. When it was done, it looked fabulous. I was almost embarrassed at how white they were. You definitely feel like you glow in the dark.
However, as time went along and I was careful about coffee and soda, it began to fade. Roughly 4 months later the benefits of my teeth whitening investment had gone away.
I called the dentist office and they said I could do it again, but that there's no guarantee that it would work better or last longer. I was pretty disappointed and for the money I wished it would have lasted longer.
Bottom line: it may work better for you, as my family tends to have the typical yellower teeth, but my dentist says they are normal white.