Similar term(s): dentin.
Dentine is an ivory-like substance that forms the inner layer of a tooth
(covered by the enamel) and the bulk of the hard-tissue component of a tooth.
Dentine is softer than enamel.
Cross-sectional view of a tooth
Source: Sam Fentress
(GNU Free Documentation license)
Crystal lattice - Dental fluorosis - Dental pulp - Enamel
To read about this term in context:
GreenFacts Summary on Tooth Whiteners & Oral Hygiene Products containing hydrogen peroxide: