works but painful [SEP] i started using this a few weeks ago at first it was not painful hardly at all and it is true after days i was definitely noticing a difference and was very pleased but the last time i put them on it was so painful i had to take them off after minutes i plan to go back to them again but am a little leary of the pain right now however my teeth are sensitive so this might not be the case for everyoneoverall very happy with the difference it has made in the color of my teethjust wish it was less painful