Some mums do find that their baby's new teeth graze, or rest on the breast for a little while. Often paying close attachment to position can help - make sure your baby is still nice and close (tuck her legs in around you to bring her chin closer if you are not sure) and that she is at the right height. If the positioning is good the teeth shouldn't hurt. Also some mums find that their baby's saliva changes during teething and can irritate their nipple area. If you think this might be the case, rinsing your nipple with 1 tsp of bi-card of soda dissolved in a cup of water seems to help.