My DD gets "pinned down" every time, I guess. I lay her on her back, head between my legs and I pin down her arms with my thighs. Sometimes she fights me, but usually I'll say, "Time to brush your teeth!" and she'll lay right down.
I floss and brush her teeth this way and am usually able to do a pretty good job if she doesn't feel like chewing on the toothbrush. I kind of hold her mouth open if I need to
Single mama to my sweet D. Taking life one day at a time.