I let my daughter "brush" her own teeth for as long as she wants (within reason), then I "finish" brushing her teeth. Letting her do it and telling her what a big girl she is and what a great job she is doing helps. I try not to force or argue... one of the things I would do when she would say early on that she did not want to brush is- start talking about what books she wanted to read before bed. Then I would tell her that she had to brush her teeth or we could not read the books. I don't think of it as bribing, I feel I am teaching her consequences to her choices. It worked for me.
Also, my dentist explained to me that there is no CONCLUSIVE research that proves that adding floride to tooth paste helps prevent tooth decay. He did explain that floride is one of the few things that can cross the blood-brain barrier. It can celate (combine) with mercury, alluminum and other metals and bring them into the brain. He HIGHLY recommends no tooth paste for the whole family!
One additional thing, my daughter LOVES to imitate me (I think most all children do). So we always brush together!
Best of luck!