In my experience top teeth have always hurt when they're coming in, regardless of biting or resting. One PP suggested our breasts get used to the teeth, I agree. My DD got her bottom teeth at 5.5 months, no big deal but she got her first top tooth at 8 months, it hurt my nipple from the time it came in until about 3 weeks later. Now at 9.5 months her second top tooth has emerged and it is painful as well. I'm hoping the pain passes soon
She has bit a few times, once drawing blood on both top and bottom of nipple...excruciatingly painful for days. Be firm in telling your LO no biting, do not bite or what ever you chose to say and make sure you remove lo from the your breast for a period of time so that biting = no milk. Good luck. Give it a few weeks cause it gets a lot less painful and they're so much fun to nurse the bigger they get Good Luck!!