cementum

juurisementti puhekieltä A bony substance that covers the root of a tooth; cement.
2005, Herbert F. Wolf, Klaus H. Rateitschak, Periodontology, http://books.google.com/books?id=LIQ_J5WzuKUC&pg=PA14&dq=%22Cementum%22&hl=en&ei=G0mBTvHUIcjZmAWS3s0r&sa=X&oi=book_result&ct=result&resnum=2&ved=0CC8Q6AEwAQv=onepage&q=%22Cementum%22&f=false page 14,

From a purely anatomic standpoint, root cementum is part of the tooth, but also part of the periodontium.