Deck 20: Enamel, Dentin, and Pulp

Question 1

The enamel rod is somewhat parallel to the dentinoenamel junction (DEJ) because it runs all the way from the DEJ to the surface of the tooth.

A) Both the statement and the reason are correct and related.
B) Both the statement and the reason are correct but are NOT related.
C) The statement is correct, but the reason is NOT correct.
D) The statement is NOT correct, but the reason is correct.
E) NEITHER the statement NOR the reason is correct.

Answer 1

C
The enamel rod is a column that runs all the way from the DEJ to the tooth surface in a direction perpendicular (90 degrees) to both the tooth surface and the DEJ.

Question 2

After the ameloblast secretes the primary enamel cuticle it is called the reduced enamel epithelium because it becomes flattened and blends with outer enamel epithelial cells.

A) Both the statement and the reason are correct and related.
B) Both the statement and the reason are correct but are NOT related.
C) The statement is correct, but the reason is NOT correct.
D) The statement is NOT correct, but the reason is correct.
E) NEITHER the statement NOR the reason is correct.

Answer 2

A
This statement correctly describes the final phase of the ameloblast. The term reduced enamel epithelium is appropriate because the ameloblast is "reduced," and it blends in with outer enamel epithelial cells. Note that the primary enamel cuticle, the final product of the ameloblast, is also called Nasmyth's membrane.

Question 3

The bulk of the dentinal material is called primary dentin or regular dentin. An area of higher crystalline content immediately surrounding the dentinal tubules is called sclerotic dentin.

A) Both statements are true.
B) The first statement is true; the second is false.
C) The first statement is false; the second is true.
D) Both statements are false.

Answer 3

D
The bulk of the dentinal material is called intertubular dentin. An area of higher crystalline content immediately surrounding the dentinal tubules is called peritubular dentin. (Hint: peri means around.) Regarding incorrect terminology, primary or regular dentin is the structure that exists when a tooth erupts into the oral cavity. In sclerotic dentin, a condition caused by occlusal trauma or decay, the empty dentinal tubules become filled with a dentin material.

Question 4

A sign that enamel production is completed is when the

A) Ameloblast moves away from the dentinoenamel junction (DEJ)
B) Striae of Retzius are seen
C) Maturation stage of calcification is reached
D) Ameloblast contacts the outer enamel epithelium (OEE)

Question 5

During the mineralization stage of enamel rod calcification approximately half of the hydroxyapatite crystals are deposited because the remaining half are deposited during the maturation stage.

A) Both the statement and the reason are correct and related.
B) Both the statement and the reason are correct but are NOT related.
C) The statement is correct, but the reason is NOT correct.
D) The statement is NOT correct, but the reason is correct.
E) NEITHER the statement NOR the reason is correct.

Question 6

Enamel is generally yellowish in color but usually appears white because of the reflection of the color of the underlying dentin.

A) Both the statement and the reason are correct and related.
B) Both the statement and the reason are correct but are NOT related.
C) The statement is correct, but the reason is NOT correct.
D) The statement is NOT correct, but the reason is correct.
E) NEITHER the statement NOR the reason is correct.

Question 7

Each of the following is true of enamel EXCEPT one. Which one is the EXCEPTION?

A) Enamel is the hardest structure of the body.
B) Enamel is developed from the inner enamel epithelium, which is derived from mesoderm.
C) Enamel is about 96% inorganic.
D) Enamel structure is composed of the rod sheath and the enamel rod.

Question 8

For both primary and permanent teeth the process of tooth development is the same. Development occurs simultaneously in the anterior and posterior regions beginning at the cervical line and progresses toward the incisal/occlusal edges.

A) Both statements are true.
B) The first statement is true; the second is false.
C) The first statement is false; the second is true.
D) Both statements are false.

Question 9

Pulp tissue consists of blood vessels, lymphatic vessels, nerves, fibroblasts, and collagen fibers. The nerves of the pulp are primarily sensory and transmit both pain and thermal sensations.

A) Both statements are true.
B) The first statement is true; the second is false.
C) The first statement is false; the second is true.
D) Both statements are false.

Question 10

Each of the following accurately describes hypocalcified enamel EXCEPT one. Which one is the EXCEPTION?

A) Hydroxyapatite crystals are not full size.
B) The tooth may be more caries prone.
C) The enamel is less dense.
D) The enamel is more than 96% inorganic.

Question 11

Young people are less susceptible to permanent pulpal damage than older people because with age the smaller pulp loses its reserve cells and is less able to resist trauma.

A) Both the statement and the reason are correct and related.
B) Both the statement and the reason are correct but are NOT related.
C) The statement is correct, but the reason is NOT correct.
D) The statement is NOT correct, but the reason is correct.
E) NEITHER the statement NOR the reason is correct.

Question 12

The dental papilla is derived from the ectoderm. It determines the shape of the developing crown.

A) Both statements are true.
B) The first statement is true; the second is false.
C) The first statement is false; the second is true.
D) Both statements are false.

Question 13

The dentin matrix creates a barrier between the dental papilla and the preameloblasts. With the resulting fluid shift and change in polarity, the preameloblast becomes an ameloblast.

A) Both statements are true.
B) The first statement is true; the second is false.
C) The first statement is false; the second is true.
D) Both statements are false.

Question 14

An enamel spindle is an ameloblastic process that becomes trapped in the dentin. Enamel spindles form in early development and are seen only histologically.

A) Both statements are true.
B) The first statement is true; the second is false.
C) The first statement is false; the second is true.
D) Both statements are false.

Question 15

Enamel, dentin, and pulp develop from the enamel organ. Enamel is derived from ectoderm whereas dentin and pulp are derived from mesoderm.

A) Both statements are true.
B) The first statement is true; the second is false.
C) The first statement is false; the second is true.
D) Both statements are false.

Question 16

Each of the following is true of enamel lamellae EXCEPT one. Which one is the EXCEPTION?

A) Lamellae are cracks in enamel that rarely extend through the enamel.
B) Enamel lamellae may provide a pathway for bacteria into enamel.
C) The most common type of lamellae is caused by trauma.
D) Rapid changes in temperature from food and drink commonly cause lamellae.
E) An infrequent type of lamellae is a developmental defect.

Question 17

Each of the following is true of the cells of the inner enamel epithelium (IEE) during the bell stage EXCEPT one. Which one is the EXCEPTION?

A) The cells increase in length.
B) The cells prepare to become secretory cells.
C) Their organelles increase.
D) There is a decrease in mitochondria.

Question 18

The multi-pointed cells that become dental papilla cells are called

A) Inner epithelium cells
B) Preameloblasts
C) Mesenchymal cells
D) Secretory cells

Question 19

Following mild trauma, which type of dentin is formed?

A) Reparative
B) Secondary
C) Sclerotic
D) Interglobular

Question 20

The portion of the enamel rod that contains most of the fibrous organic substance is the

A) Enamel rod
B) Enamel matrix
C) Ground substance
D) Enamel sheath

Question 21

The asymmetrical bulging end shape within the ameloblasts is called the

A) Imbrication lines
B) Striae of Retzius
C) Tomes' process
D) Maturation phase

Question 22

The dental papilla has genetic control over tooth shape.

Question 23

Hundreds of odontoblasts are damaged when restoration is prepared and placed within a tooth. Sclerotic dentin forms in response to the trauma.

A) Both statements are true.
B) The first statement is true; the second is false.
C) The first statement is false; the second is true.
D) Both statements are false.

Question 24

The primary abnormality seen in pulp is pulp stones.

Question 25

During the maturation stage of calcification, an ameloblast produces enamel at what rate?

A)0.02 mm per hour
B) 2 mm per day
C) 4 mm per day
D) 10 mm per hour

Question 26

The typical enamel rod is shaped wider at the top and more narrow at the bottom because the hydroxyapatite crystals in those portions differ in size.

A) Both the statement and the reason are correct and related.
B) Both the statement and the reason are correct but are NOT related.
C) The statement is correct, but the reason is NOT correct.
D) The statement is NOT correct, but the reason is correct.
E) NEITHER the statement NOR the reason is correct.

Question 27

Which of the following are true of pulp stones (select all that apply)?

A) They are small, circular, calcified areas.
B) They occur in about 50% of people aged 70 to 80 years.
C) True pulp stones originate from ameloblasts.
D) False stones are most common.
E) False stones resemble an onion cut in cross section.

Question 28

Tooth development is first seen at the incisal edge or cusp tip.

Question 29

Peripheral cells of the dental papilla are called ameloblasts.

Question 30

Once formed, the often stained primary cuticle can be removed by (select all that apply):

A) Regular toothbrushing
B) Dental scaling
C) Dental prophylaxis
D) Tooth bleaching

Question 31

The reduced enamel epithelium secretes the primary enamel cuticle.

Question 32

The size of pulp horns and chambers do not vary significantly with age.