I had read horror stories, but two weeks before the Zoom my dentist made me trays and I did a daily flouride treatment for 10 days prior. I had NO pain whatsoever and I DO have sensitive teeth. The technician and dentist were METICULOUS in the application and treatment and I had NO burning of tissue.
I have been given explicit instructions post treatment to avoid certain foods for three days and a booster whitener for the next two days.
I paid a LOT of money for it, but I got the best. When I read the prices and the stories I think some people are pushing this for cheap and not really expert at doing it.