Why do electric toothbrushes have small heads?

Because they are very efficient and there is no need to have it larger. Also because they spin the head, if you would like to spin a large head there is no need nor efficiency in that. The small head spins at around a hundred rotations per second, a large and heavy head cannot do it. read more

As with a manual toothbrush, the best electric toothbrush for you is the one you like and will use every day. Electric toothbrushes come in different sizes, too. In general, the replaceable heads of electric toothbrushes are smaller than the full-sized head of a manual toothbrush, so if you are used to a full-sized head, the electric toothbrush may take some getting used to. read more