Which of the following lists the structures in order of decreasing radiopacity?

A) Pulp, dentin, cementum, enamel
B) Enamel, dentin, cementum, pulp
C) Pulp, cementum, dentin, enamel
D) Enamel, cementum, dentin, pulp

B
Explanation: A) Enamel, the hardest body structure, covers the crown and is very radiopaque. The underlying dentin is not as dense and appears less radiopaque. The cementum that covers the roots is even less dense. The tooth pulp that occupies the pulp chamber and the root canals is the only noncalcified tooth tissue. As this soft tissue offers only minimal resistance to the passage of x-rays, it appears radiolucent.
B) Enamel, the hardest body structure, covers the crown and is very radiopaque. The underlying dentin is not as dense and appears less radiopaque. The cementum that covers the roots is even less dense. The tooth pulp that occupies the pulp chamber and the root canals is the only noncalcified tooth tissue. As this soft tissue offers only minimal resistance to the passage of x-rays, it appears radiolucent.
C) Enamel, the hardest body structure, covers the crown and is very radiopaque. The underlying dentin is not as dense and appears less radiopaque. The cementum that covers the roots is even less dense. The tooth pulp that occupies the pulp chamber and the root canals is the only noncalcified tooth tissue. As this soft tissue offers only minimal resistance to the passage of x-rays, it appears radiolucent.
D) Enamel, the hardest body structure, covers the crown and is very radiopaque. The underlying dentin is not as dense and appears less radiopaque. The cementum that covers the roots is even less dense. The tooth pulp that occupies the pulp chamber and the root canals is the only noncalcified tooth tissue. As this soft tissue offers only minimal resistance to the passage of x-rays, it appears radiolucent.