Dumas is HORRIBLE to bridle.
we are working on it with him. I have found that honey on the bit (although I have to clean my hands) helps. Once he gets it on his lips he is a little more accepting. Though I don't have the problem when unbridleing him, he basically spits the bit out happily.
I haven't had his teeth done yet either.
ETA- Dumas is headshy and that, I believe is the root of his problem.