i used electric toothbrush for years. a couple of years ago, my dentist that i still wasn't doing a good job with brushing. i found out from my dentist, you just don't put the brush in your mouth, and turn it on. you brush like a regular toothbrush, i stick the brush in front of my teeth, and turn it on. it tickle me and lift one leg and itched my other leg with it, and i bark.
to me, a electric toothbrush waste my time, i use a regular toothbrush now. and good news, i stop wagging my tail and itched my leg, when i brushed my teeth.