Review (1/5): DON'WASTE YOUR $$$. Useless and stops intermittently.
This things does nothing but rattle your teeth. I spent at keast 15 minutes on one area of a tooth that has some calculus, but not much. It only managed to make my gums bleed and rattle my teeth. I tried different speeds and different teeth and there was no effect. It quits vibrating randomly for about 2 seconds, which is annoying. Using the supplied manual dental pick is easier and actually removes stains, but the vibrating piece of junk is useless.