The Collaborative International Dictionary of English v.0.48:

Dentine \Den"tine\ (d[e^]n"t[i^]n), n. [Cf. F. dentine.] (Anat.)
   The dense calcified substance of which teeth are largely
   composed. It contains less animal matter than bone, and in
   the teeth of man is situated beneath the enamel.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dentine
    n 1: a calcareous material harder and denser than bone that
         comprises the bulk of a tooth [syn: dentine, dentin]
    2: bone (calcified tissue) surrounding the pulp cavity of a
       tooth [syn: dentine, dentin]