Deck 20: Enamel, Dentin, and Pulp

Question 1

Enamel,dentin,and pulp develop from 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 statement is false.
C) The first statement is false;the second statement is true.
D) Both statements are false.

Answer 1

C
Enamel develops from enamel organ,which is derived from ectoderm.Dentin and pulp develop from the dental papilla,which is derived from mesoderm.

Question 2

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

Answer 2

B
While the nerves of the pulp are primarily sensory,the only type of sensation they transmit is pain.

Question 3

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 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.

Answer 3

A
Lamellae are hairline cracks in enamel that may extend into dentin.An infrequent type is a developmental defect that results from cessation of enamel production by one or more ameloblasts.This defect leaves a space between enamel rods,which provides a potential pathway for bacteria.

Question 4

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) Enamel is less dense.
D) Enamel is more than 96% inorganic.

Question 5

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

Question 6

Following mild trauma,which type of dentin is formed?

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

Question 7

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

Question 8

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.

Question 9

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 10

An enamel spindle is an ameloblastic process that becomes trapped in 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 statement is false.
C) The first statement is false;the second statement is true.
D) Both statements are false.

Question 11

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 enamel rod.

Question 12

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

Question 13

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 14

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 15

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.

Question 16

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

Question 17

The portion of 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 18

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 19

A sign that enamel production is completed is when

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

Question 20

The multipointed cells that become dental papilla cells are called

A) inner epithelium cells
B) preameloblasts
C) mesenchymal cells
D) secretory cells

Question 21

Peripheral cells of the dental papilla are called ameloblasts.

Question 22

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 23

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 24

The dental papilla has genetic control over tooth shape.

Question 25

Which of the following is NOT an abnormality in dentin?

A) Interglobular dentin
B) Sclerotic dentin
C) Dead tracts
D) Reparative dentin

Question 26

The typical enamel rod is shaped wider at the top and narrower 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

The reduced enamel epithelium secretes the primary enamel cuticle.

Question 28

The primary abnormality seen in pulp is pulp stones.

Question 29

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 30

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

Question 31

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

Question 32

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

Question 33

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