I did. That's why I know what I suggested works. My mom was a genius at reverse psychology and making me thing it was my idea, not hers.
That's what works with my stubborn little man too.....reverse psychology. At 4, there's not much he gets to control in life. So he fought me on potty training and eating because that's pretty much all I couldn't "force" him to do. Once he thought he had some control, he did it. Yes, reverse psychology is the way to go in my house for sure!
But then you are just coating your teeth right after you brush them?
Like wiping your ass before you chit instead of after.
Reward system? He has two choices. He brushes them, or you do.
If he does it, reward him with a star, marble in a jar something. Make it easy at first to earn his big reward (three marbles and he can have XYZ)
Start increasing the number of marbles it takes to earn his next big reward. You know what his triggers are.
Sticker charts helped my son with potty training and behavior. Positive reinforcement works really well for him, although if he needs a swat on the butt he gets that too. Luckily he loves to brush his teeth. Now if only I could get him to try new foods, I'd be thrilled. He must be the world's pickiest eater!