Hi, the Dentist told me a couple of years ago that my Husband was not brushing the backsof his teeth, up until that point he had taken care of his own teeth with manual toothbrushes. I purchased a battery operated toothbrush, he couldn't get used to it and didn't understand when I told him to do the back of his teeth, he prefers to interpret this as his back teeth, so I now clean his teeth with the battery toothbrush. I can't pretend he likes me doing it, but I manage. He is unable to move his tongue when I ask him, particularly on the one side of his mouth to enable me to do the backs and back teeth, but keeps pushing on the toothbrush with his tongue and doesn't understand what I mean when I ask him to lift it or move it to the other side of his mouth. When we go to bed at night I let me do it himself with his manual toothbrush, I just can't face the tussle with the battery operated brush when I am tired and wanting to go to bed. You can only do your best.