Hi N.,
Please look at my profile to see my experience on this subject. With that said, I agree with Page. At around a year old, I too had to lay my daughter on the floor and restrain her while I brushed. You may also try putting her in your lap with her head between your knees. Right now it is about control and I'm sure this will not be the last power struggle you have. The bottom line is NO toddler does a good enough job brushing and parents need to get in there and really brush. Some kids do okay with taking turns. When I had to restrain my daughter while brushing, I would tell her "When you hold still and open for Mommy I will let you sit up. It can be easy or it can be hard, your choice, but it has to be done." We also talked alot about the tooth bugs that eat her teeth and how we need to brush them away. I also took her to meet her dentist and had him tell her the same thing. I also use Oral-B Baby toothpaste with xylitol.
Hope this helps!
L.