Deck 7: Enamel

Question 1

Light and dark enamel rod groups are known as striae of Retzius.

Answer 1

False

Question 2

Enamel is composed of ______ hydroxyapatite.

A) 26%
B) 53%
C) 90%
D) 96%

Answer 2

96%

Question 3

Lamellae are cracks in the surface of enamel and are visible to the naked eye.

Answer 3

False

Question 4

The neonatal line is best defined as which of the following?

A) An accentuated incremental line
B) A defect caused by the misdirection of enamel rods
C) Light and dark enamel rod groups, made visible with light
D) A series of dark growth rings noticeable in the cross section of enamel

Question 5

Ameloblasts travel along parallel paths to produce straight enamel rods.

Question 6

Which of the following best defines perikymata?

A) Termination of dentinal tubules in enamel
B) Alternating dark and light bands of enamel rod groups
C) Growth lines visible as ridges on the surface of enamel
D) Lines that result from the rhythmic recurrent deposition of enamel

Question 7

Perikymata are found in which location?

A) Cusp tip
B) Cervical third of the root
C) Middle third of the crown's lingual aspect
D) Cervical third of the crown's facial aspect

Question 8

Ameloblasts migrate away from the dentinoenamel junction as they produce enamel rods.

Question 9

Which type of enamel contains many tiny spaces stained with pigment?

A) Gnarled
B) Prenatal
C) Postnatal
D) Prismless

Question 10

Enamel varies in density and hardness.

Question 11

Which part of the enamel rod is most sensitive to demineralization?

A) Tail
B) Core
C) Head
D) Sheath

Question 12

Enamel is approximately ______thick at the occlusal or incisal surface.

A) 1 µm
B) 9 µm
C) 2.5 mm
D) 4.5 mm

Question 13

Which of the following best defines incremental lines?

A) Ridges visible on the surface of enamel
B) Termination of dentinal tubules in enamel
C) Alternating dark and light bands of enamel rod groups
D) Lines that result from the rhythmic recurrent deposition of enamel

Question 14

Ameloblasts produce _______ as they migrate.

A) cementoid
B) enamel rods
C) epithelial rests
D) dentinal tubules

Question 15

Ameloblasts deposit 4 µm of enamel rods daily.

Question 16

Which statement is true?

A) Tubular defects are associated with enamel lamellae.
B) Lamellae provide increased resistance to dental caries.
C) Breathing cold air is a risk factor in developing enamel lamellae.
D) Enamel lamellae are microscopic cracks in the surface of enamel.

Question 17

Which of the following does not facilitate the spread of dental caries?

A) Enamel tufts
B) Enamel lamellae
C) Incremental lines
D) Prismless enamel

Question 18

Tertiary enamel is deposited in response to structural damage.

Question 19

An enamel ______ houses a small extension of a living odontoblast.

A) rod
B) tuft
C) spindle
D) lamellae

Question 20

Enamel rods extend from the dentinoenamel junction to the enamel outer surface.

Question 21

Enamel is an impermeable tissue.

Question 22

Hunter-Schreger bands extend through half to two thirds of the enamel.

Question 23

Enamel rods extend perpendicular to the dentoenamel junction,but curve slightly toward the cusp tip.

Question 24

The surface of an enamel rod is called the ______ _______.

Question 25

Two ameloblast cells form the enamel rod _________.

Question 26

In the Hunter-Schreger phenomenon,adjacent rod groups lie at right angles to each other.

Question 27

Name the organic component of enamel.

Question 28

Prismless enamel is characterized by numerous and pronounced Hunter-Schreger bands.

Question 29

Etching the surface of enamel stimulates remineralization.

Question 30

Each enamel rod is formed by a single ameloblast.

Question 31

A tuft is a developmental defect in enamel filled with _________ material.

Question 32

Enamel lamellae are not tubular defects,but leaflike tracts.

Question 33

Incremental lines result from the rhythmic,recurrent deposition of enamel.