Well, I had a hard one too. We started with the rubber finger brush and the baby gel early on, and that was fine until we actually had more teeth. I basically just fought my kid for 2 years, lots of biting and kicking. We went to the dentist for the first time, and got instructed on how to do it the proper way, and I was skeptical until we actually did it.
If you do it alone, you need a big enough blanket to swaddle arms and legs down tightly, and then do it in a quick and soothing a manner as possible.
If you have a partner to double team, get on the floor and hold the child's head gently but firmly in your lap, holding the arms down and crossing them on the child's chest so they can't push or hit. The partner pulls the kid's legs around the waist to keep them from kicking the face and chest, and leans in to brush the teeth, telling the child to "open up like at the dentist" and "show me your shiny, pretty teeth". With both of us praising her during the whole thing, it just became less and less traumatic. Phew. When we do it now, she chooses who does the brushing and yells "FASTER! SHINY!"
Sounds terrible to "hold down" a kid to do this, but it's a lot better than the way I was doing it, with my husband holding her down and my scrubbing as fast as possible between the screams, bites, and spitting. Also, we can do it really thoroughly, and the dentist taught us a quick technique to brush the sides and back, which was always a fight.
She likes to "do it" herself, but mainly gets the one molar and her teeth were becoming decalcified because we were giving up too often and letting her breastfeed to calm her down after the trauma of a toothbrushing.
I think the visit to the dentist really helped too, because she got to see other kids on the dental tables and opened her mouth and learned a few of the tools. She was really brave, and now brushing is actually 100% easier.
The dentist told us that we were really doing the right thing by forcing it, which always made me feel abusive and miserable and guilty. But when I saw the white lines in her teeth showing decalcifications, I got scared and firm. A few times with the combo hold and giving her the choice to have mommy or daddy do it, plus she is FINALLY used to the motorized hello kitty tooth brushes (which make it very quick and much easier to do all around), the whole thing is finally working at 30 months.
So don't give up, eventually your kid will smile, open his mouth, and let you brush the gunk off without a giant balls out fight. I seriously thought I'd be brushing teeth by force until she was six, but the dentist was right!
More tips: -let the child brush teeth in the AM, but make sure you do it thoroughly at night "You can do it in the morning, but Mommy has to do it at nigh, that's just the rules."
-If you can't do anything at all toothbrush-wise, wiping the teeth with a washcloth or a damp piece of gauze is better than nothing
-with the hold-down and brush technique, keep a damp cloth nearby so that you can wipe spit away and paste off the teeth
-if your kid can't handle toothpaste, it's okay to brush without, because they don't need the flouride as much as they need to disrupt the formation of plaque and bacteria
-don't give anything but water after brushing the teeth, not even breast milk
-buy a picture book about teeth, brushing, etc
-have your kid help you brush the dog's teeth (seriously. Lots of oohs and ahhhhs and "missed spot, mommy!")
We have noticed our daughter even likes to look in the mirror and view her shiny teeth nowadays, so the best tip is: don't give up!
Good luck!