Here are some suggested organisations that offer expert advice on special needs.
Asd - tried all sorts over the years and now she’s not brushing at all! 🙈😬
Blossom ds (asd) did have a phase of this when he was 2-4 (you don't mention how old dd is?) I use to have to literally pin him to do it, bloody brutal with him kicking me in the head and grabbing my hair etc, absolutely dreaded doing it every day.
He's much better now! (he's 6) and I have no issues brushing his teeth anymore.
Can you just get the toothpaste in her mouth for the fluoride, would she use mouth wash? You can buy oranurse flavour / foam free toothpaste, would she have an electric toothbrush she could pick? Ds has always been shit scared of electric toothbrushes but suddenly after seeing mine (that I've used for ages but he's only just took a shine to it) I've just got him one and he's happily using it. Prior to the electric one he liked peppa pig so just had a peppa brush and I let him choose a kids toothpaste.
Could you do them in her sleep or get the fluoride in her mouth when asleep?