591. Primary enamel cuticle is:
A.Afibrillar cementum.
B. Precipitate of salivary proteins.
C. Relatively structureless layer of enamel.
D. A last product of ameloblasts.
592. Hunter-Schreger bands have all the following characteristics except:
A. They are best seen in reflected light.
B. They are alternating dark and light bands
C. They are most likely an optical phenomenon
D. They are found at the cusp tip.
593. Enamel tufts and enamel lamellae resemble each other in that both:
A. Are formed prior to tooth eruption only.
B. Extend over full thickness of the enamel.
C. Are hypermineralized structures.
D. Are hypomineralized structures.
594. Enamel is by weight:
A. 70% mineral, 26% organic matrix, 4% water.
B. 76% mineral, 20% organic matrix, 4% water.
C. 25% mineral, 12% organic matrix, 3% water.
D. 95% mineral, 1% organic matrix, 4% water.
595. All of the following structures in enamel are ectodermal origin except:
A. Enamel spindle.
B. Enamel prisms.
C. Enamel lamellae (type A).
D. Enamel tufts.
596. Enamel is:
A. An ectodermal tissue covering the anatomical crown.
B. A mesodermal tissue covering the crown.
C. An endodermal tissue.
D. A mesenchymal tissue.
597. Gnarled enamel has the following criteria except:
A. Found under cusp tips and incisal ridges.
B. The course of the enamel rods is more straighter.
C. The enamel rods become twisted and braided.
D. Found to give maximum strength to the areas subjected more to the masticatory forces.
598. The peripheral part of the E rod is called:
A. Interrod region.
B. Rod sheath.
C. Rod region.
D. Key hole.
599. Concerning the rod sheath, one of the following statement is incorrect:
A. It occupies the peripheral part of the E. rod.
B. It forms the border where crystals of the rod and interrod enamel meet.
C. It is highly calcified than the rod.
D. It has a higher organic content thus resists decalcification more than the rod.
600. The interrod enamel is:
A. More calcified than the E. rod.
B. Less calcified than the E. rod.
C. The same calcification as the E. rod.
D. Organic in nature.
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