It's awful isn't it, what pregnancy does to your teeth!
When Dora was about 4-5 weeks old, I had to have 2 teeth out. the dentist said that the anaesthetic wouldn't affect breastfeeding, but I chose to have it done under sedation, so couldn't feed for 24 hours. It was the longest 24 hours ever!
Luckily, my sister had a baby 3 weeks before me and is breastfeeding her baby, so she came over for the day with him, and fed mine too! She was absolutely shattered the day after though... I'm surprised she hadn't completely wasted away, she was feeding one or the other all day!