Well, I stopped brushing my kids' teeth when they were each about 5, BUT DON'T MAKE THE SAME MISTAKE I DID!!!
I thought that my kids had great hygeiene, they brush every morning and night. They floss every night. They rinse with mouthwash every night.
Things went fine for my older daughter, but not so with my younger. Apparently her teeth are really cramped. I didn't realize that she wasn't getting the floss all the way down in between the teeth. I don't think that my older one has been doing this either.
I just went to the Dentist this last tuesday - and I found out that my older daughter has 2 cavities. My younger - 4 cavities and also she'll need 2 BABY ROOT CANALS!!!! I feel terrible.
The hygienist gave me the following advice: let your kids brush their teeth on their own for 2 minutes. Then YOU floss. And YOU brush their teeth - for about 30 seconds - making sure to get all of the teeth. Then, have them rinse with ACT (this is the BEST brand for preventing cavities) for a whole minute. Make sure they don't have anything to eat/drink for at least 45 minutes after the mouthwash. (we do that the LAST thing at night.)
Anyways. it sounds like a lot of work, and it does take a few minutes, but I wish I'd been doing it earlier. It would have saved me at least $800 (and that's AFTER insurance).
Good luck.
C.