Question

A newly erupted tooth is covered by:

• A. Perikymata
• B. Nasmyth's membrane
• C. Fibrous tissue
• D. All of the above

Hint:

Reduced enamel epithelium becomes the primary enamel cuticle over the new crown.

Answer 1

The Correct Option is B

Step 1: When a tooth first erupts into the mouth its crown carries a thin membrane on its enamel surface. This needs to be identified.
Step 2: That covering is the primary enamel cuticle, also called Nasmyth's membrane, which is the reduced enamel epithelium left behind by the ameloblasts after enamel formation. It protects the enamel from resorption by cells of the dental sac and helps the tooth erupt without bleeding. So the newly erupted tooth is covered by Nasmyth's membrane.
Step 3: Why the others are wrong. Perikymata are the surface ridges of enamel that mark the lines of Retzius; they are a feature of enamel itself, not a covering membrane. Fibrous tissue is not the specific covering of an erupted tooth. Since only one option is correct, 'all of the above' is wrong.