Good luck anyone who tries this. It works. I've done it on all five of mine.
Keep in mind that you never ask for more than the dog can give, but when you ask, don't take no for an answer. You are confident, for instance, that doggy can let you touch his mouth with the toothbrush so keep in mind that you are the leader and dog will submit to you. Which means that you have dog in a position from which she/he can't run away. Not restrictive so he's scared but enough for you to have control. You calmly lay back of brush against his mouth. She might want to dodge away from it, but we know she's not being hurt. CALMLY insist that she accept it, then release. The release is as important as what you intend to accomplish. Doggy must learn that submission earns relief. Take heart from the smallest of victories. This is not meant as punishment, but in dog's best interest, but dog has to be led, not forced, into it. Release is our friend.