This seems to be a current topic of conversation in my mom-baby group, as many of our kids have multiple teeth. Cupcake still only has her 2 bottom teeth, but they're razor sharp. And yes, sometimes she bites.
We went through a bad biting stage for a while, and I asked my local La Leche League chapter for their advice. They are such a great source of information, even if I still find them overly AP for my tastes. Also, through asking other people, I've come up with a brief summary of some techniques to deal with a compulsive biter.
Here goes:
Reprimand : Pull them off the boob and say NO! very firmly. Then put the milk (boob) away. This didn't work for us. Cupcake found it hi-la-rious. Which then would make me laugh, and well... it wasn't getting the point accross. At the LLL meeting, many ladies said that this technique works in theory, but not in practice.
Distract and underplay the reaction: Many times, yelling Ow! in pain or telling them a firm NO! can be counterproductive, because most babies laugh at the attention. Instead, try to have a non-reaction. When they bite, pull them away (making sure to insert your finger in their mouth so you're not pulling your nipple out while biting, ouch!), and cover your boob. They will cry, and you distract them with a teething toy in their mouth, or something else in their hands. When they're calmed down a bit, start breastfeeding again. Repeat for as many times as necessary until they seem to get it.
Know that this too, shall pass. Just because the baby has started biting all the time, it doesn't mean this is the new normal. Like everything else, they go through phases. Cupcake had a terrible week right before her first tooth came him, and I was basically ready to end our breastfeeding relationship. I gave myself a deadline for a week away, if she wasn't done biting by then, we'd have to use formula. Her tooth came in before that time (lucky girl) and she stopped biting. Still bites once in a while, but it's very seldom. Right now she's teething again, so she'll bite more, but it's not a chronic issue.
Prevent the bite. Observe their biting habits. Are they biting at the end of the nursing session, before the let-down, when they're done with one side? Maybe they're done drinking for a bit and need to teeth. Have a cold teething toy close at hand. And when they're drinking, observe closely if the sucking motions are slowing down, then pull them off the boob and insert a teething toy in their mouth. As in, try to pre-empt the bite. I've never been able to actually do this. Cupcake always catches me by surprise.
Nurse when well rested. Many times, they bite out of frustration or tiredness. See is you can feed them at times when they're not dying for a nap. This has really worked for us.
Change nursing positions. For example, Cupcake will only bite me when she's laying down. If she bites, I switch her to sitting. She sits on my lap, facing me, with the boob on her face. Looks hilarious, but it seems to distract her enough.
The boob smother. The Dr Sears recommended method of pushing the biter's head into your breast. Effectively, this smother forces them to have to open their mouth and they can't bite (it saves your nipples too) Repeat as many times as necessary until they get the point.
Any other techniques you would like to share? I'm always open to breastfeeding advice.