Home Womens Fashion I will no longer waste money on Crest Whitestrips! Arm Hammer Whitening Booster is meant to be used when brushing your teeth. I use a q-tip and coat my teeth with it and leave it for only 10 minutes (since it claims to be 3x stronger than strips) once a day…seriously youll notice a difference in 2 days! Be careful if youre sensitive!