Dentin, which is harder than bone, surrounds the pulp of these
Archive - Show #5276, aired 2007-07-16 [PAR] Technically, a carpet is fixed to the floor but one of these lies free .... Dentin, 
which is harder than bone, surrounds the pulp of these... [DOC] [TLE] Dentin - Wikipedia [PAR] Dentin (American English) or dentine (British English) (Latin: substantia eburnea) 
is a calcified tissue of the body and, along with enamel, cementum, and pulp, is 
one of the four major components of teeth.