Went for whitening. After 2nd treatment, told one of the two techs that I was having discomfort on lower teeth. She used a different formula. After a short time, a different tech came in to remove the chemicals and to put a third treatment on. I indicated that this was the third so she put another treatment back on and used the original formula. I had some pain, but not bad. About 4 hours after treatment began experiencing severe pain. On doctor’s advice, started taking 3 Advil every 6 hours. Pain is continuing, with pain killers, 20 hours after treatment. Not what I expected.