add a picture..or show it t your dentist...it has to be seen clinically

Going only by the description that you have mentioned and without a look at the clinical condition of the affected area, all we can provide is a tentative suggestion---- it seems most likely as calculus deposits or stains On The Teeth which can be removed by teeth cleaning through a procedure called as scaling. The best option would be to visit a dentist for a proper clinical evaluation so that the right treatment options can be delineated for you. Regards.