Final answer:
Dentin is a bone-like tissue that lies beneath the enamel in a tooth. It is difficult to differentiate dentin from other parts of the tooth radiographically. Enamel is the hardest material in the body and covers the crown, while cementum covers the root and alveolar bone supports the tooth in the jaw bone.
Step-by-step explanation:
Dentin is the bone-like tissue that lies immediately underneath the enamel of the crown or cementum of the root of a tooth. It is difficult radiographically to differentiate dentin from enamel, pulp, cementum, and alveolar bone. However, enamel is the hardest material in the body and covers the crown of the tooth, while dentin is a layer beneath enamel and surrounds the pulp cavity. Cementum covers the root of the tooth, and alveolar bone supports the tooth in the jaw bone.