did not work for me [SEP] i used this device for two weeks and did not notice any difference at all except for the light feeling in my wallet every time i used this i could only think of those quack ads from the s promoting various electrical devices as a cure for whatever disease you happened to have maybe i just had a bad attitude about it i do not know i any case i decided to return it and get my money back i now use a whitening toothpaste from crest and have seen some improvement from that at of the cost