Real quick, the anonymous poster is not well informed on nursing. Just so you know. Breastmilk is always helpful and always contains antibodies regardless of age. Many women will nurse exclusively for the first full year of life, but I'm sure you knew that anyway.
As to your question, bottom teeth should not be making contact with your breast at all. Baby's tongue should be the only thing he uses on the bottom. If he starts biting, put him off and do not continue to nurse him until the next time he is scheduled to eat. Anytime baby bites, just pull them off and eventually, he should stop. Some Moms will yelp or cry out when the baby bites and that can help too.
Good Luck! It's tough when they start biting. My dude doesn't bite my breasts, but he'll bite at my shirts and get skin pretty often, I'm trying to figure out how to get him to stop THAT! :)
at 4:11 PM on Sep. 22, 2010