One year old resisting tooth brushing.

It’s such a hassle to brush my one year olds teeth. We have to hold her down just to get it done. This is my first child and I made a mistake on not starting sooner when she was six months. She has eight teeth and the 4 at the bottom look fine but the top 2 of her teeth has plaque built up around the gums. When I brush them I try to do a good job but she moves a lot and cries. I feel like a bad mom because her teeth should be in better shape. I’m really worried that they will start decaying if something doesn’t change. I need advice.