Magic White

I've tried it. they hold up a colour chart to your teeth and then it takes either 3x 7min or 1x20min (depending on where you go) in front of the light. my teeth colour went up like 3 shades the first time. About 6 months later, I redid it, and another 3 shades up. Not sparkling white but now a 'normal' white colour. its good, my dentist said it was ok to do it.
however - careful to really put the protective gel everywhere (esp with the 20min long one) as otherwise your skin really gets red and sore (goes away by the next day). :)