A relatively new type of toothbrush on the market, the mouthpiece toothbrush is also known as a mouthguard toothbrush, full mouth toothbrush, and 10 second toothbrush, to name a few. A hands-free, automatic electric brush shaped like a mouthguard, the mouthpiece brush fits into your mouth and cleans it all at once in a matter of seconds with a series of nylon bristles.