We have problems with that, too. I usually tell Chase, "I will give you the brush if you'll let me brush your teeth first." He agrees but then screams and tries to pull away while I'm brushing them. I usually get in about 10 seconds of brush-to-teeth contact twice a day. He will carry around his toothbrush for an hour, though, chewing on it, so I figure he's probably doing a pretty good job himself.