I had the same thing and the dentist removed it and had it tested and it was benign, he said it was just a growth.
It looks like a boney projection we call Exostoses, it is a hallmark of a clencher usually. They are of no particular danger, however, when they get too large they can become a bit painfull as the tisse over them is distended and thin and therefore, more sensitive.
Other than than that harmless.
hope this helps.