My dentist spoke to me about Madeline's teeth when she was only 6 weeks old. Basically, once their teeth break through, it's worth getting a baby's first toothbrush and brushing. It's not even important to use toothpaste, just water if you want.

Moreso, he said that it was great if you can get baby to have a little bit of water after their last feed at night. That way their rinsing the milk off their teeth. I guess that makes sense to me... *LMAO*