Just wanted to add a comment from direct recent experience:

I'm now breastfeeding a 9 month old with teeth coming in.   Josh now has his
lower central incisors and they are razor sharp.  When he decides to clomp
down or pull away from the breast or use mommy as an emery board (creating
some chafing), IT REALLY DOES HURT! Keep in mind that I also have eczema
 (tender skin to begin with) We have also gone through bouts of yeast (ductal
only) infections, sucessfully treated.

I'd be careful assuming that the pain of biting, sawing from an tenacious
baby is not all that painful.  But the QUALITY of the pain (from my personal
perspective of course) from biting does seem to be slightly different.

I know that Gentian Violet can be helpful in treating yeast (I use it in some
but not all of my patients), but I would caution putting it on already chafed
nipples- it can in some create a feeling of burning that makes the cure
almost as uncomfortable as the problem.

Teaching my Josh to find other things to chew :)!

Pierrette Mimi Poinsett MD FAAP
Modesto CA