They clean your teeth more thoroughly.
Electric toothbrushes win hands down over manual brushes when it comes to cleaning ability. The electric version's whirring bristles remove plaque better and faster, for starters. Their more advanced designs are also able to get at hard-to-clean areas like the backs of molars and the gum line, thus helping to prevent cavities and gingivitis. Not surprisingly, then, both the American Journal of Dentistry and the British Dental Journal support the use of electric toothbrushes [source: Electric Toothbrush Reviews].
But don't just listen to the sages at dental journals. Regular folks are big electric toothbrush fans, too. In a survey of 16,000 patients published by the American Dental Association, more than 80 percent said they improved their oral cleanliness after switching from their manual toothbrushes to an electric version [source: Electric Toothbrush Reviews]. It's hard to argue with that!