What options do I have to fix hairline horizontal crack in one of my molars? (photo)

I went to the dentist about having my wisdom tooth removed. At the same time he noticed a hairline horizontal crack in one of my molars. I was not aware of it ever happening (please see pic). He said he had never seen a crack like that before. As it was an emergency appointment regarding my impacted wisdom tooth there was not time to address this finding properly. I would like to know what action (if any) I would need to take in regard to this?