Question

Which of the following BEST describes the radiopaque area on the lower one third of teeth #20, #21, #27, and #28?

1) Enamel
2) Dentin
3) Pulp
4) Cementum

Answer 1

The radiopaque area on the lower one third of the given teeth is most likely the cementum, as it covers the dentin in the tooth's root.

Step-by-step explanation:

The radiopaque area on the lower one third of teeth #20, #21, #27, and #28 would most likely be cementum. This is supported by the information that in the root of the tooth, the bone-like tissue called dentin is covered by an even harder bone-like layer known as cementum. While the outer surface, or crown, of the tooth is covered with enamel, the hardest substance in the body, the enamel does not extend to the lower third of the teeth; this area is typically covered by the gums. Beneath the enamel and extending into the root around the innermost pulp cavity is the dentin, which is less radiopaque than enamel and surrounds the pulp cavity containing the blood vessels, lymphatic vessels, connective tissue, and nerves. The pulp itself, which fills the pulp cavity, would appear less radiopaque than dentin and would not match the description provided.