Huggles, I am going to go and look for the Nature fresh brand - I haven't seen it before. Thank you!
Joy P: How does she respond to humor? Once you have sorted out the burning toothpaste (don't know why they make it so minty?)...

How about having a bit of role play with a sock puppet that absolutely refuses to brush teeth? Garanteed to bring out some laughs if you do a good perfermance! You can take turns to be the stubborn sock puppet, that way she can experience both roles, the one being stubborn (that one she knows) and the one where she has to brush the stubborn sock puppet's teeth. I have had major success with this role playing exercise because it often gives a child a chance to speak (as the sock puppet) to what is at the heart of the problem.
Perhaps she could be allowed to have a nice tasting Chewable vitamin (that is sugar free) after she has brushed her teeth? Don't k now if she loves those vitamins like my LG does?
Please let us know how it goes! I know that these battles can take a lot out of you. We have had uphill with picking up toys at the end of the day...something we struggle with!