You got to love the posters they dental offices have up of very tanned people with brilliant super white teeth! As far as I'm concerned this is false advertizing!
I did the ZOOM whitening pd. $400 about 5 years ago and I was expecting this drastic difference, only to leave the office in pain, the WORST zingers and a soft feeling that lasted for a very long time. My teeth were possibly a shade brighter, I thought it was a joke. The dental hygienist said after the fact, it depends on your teeth shade to begin with & fine weren't bad. I took home a touch up kit and they would brighten them very temporarily, the next day the slight difference faded.
I would never pay the money to torture myself again for zero results.