With my DD I used this kit you can buy at Wal-Mart or other stores. It's some baby friendly toothpaste with a little rubber thing you put on your finger to rub the toothpaste on the baby's teeth and gums. My DD would fall asleep a lot with a bottle from feeding her and I never 'brushed' her teeth afterwards. I just did it once in the evening before bed time. She is 6 yrs old and no cavaties yet. I have been taking her to the dentist since she was 2 yrs old.
Any baby friendly toothpaste you will find (no flouride) is safe to swallow in very small amounts. Your child won't spit out the toothpaste until they are old enough to learn, like 3 or 4 years old.