My son is destroying my nipples

My son has been breastfeeding for a year with no issues. Now that he has top teeth, he is leaving wounds on my breasts from his teeth. He does not bite, they are from his teeth rubbing. I cannot get him to change his latch. I think maybe he has a shallow latch. I do not want to stop breastfeeding, but I do not know what to do. The picture is where he is leaving wounds. Is there any way to get him to change his latch this far into breastfeeding? I know women breastfeed babies with teeth all the time. What are we doing wrong?