hyperkeratosis makes me think that it is rubbing against something rough ( chronically ) in the same area. Check for old restorations or something that is causing the hyperkertosis. If you find something like that, it can be polished down or replaced. If this is superficial like it sounds, it can likely just be lasered off. Many dental offices will do this for you, and are competent to do so.

Brian, stage 4 oral cancer survivor. OCF Founder and Director. The first responsibility of a leader is to define reality. The last is to say thank you. In between, the leader is a servant.