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Oral Histology > 3 Enamel Tissue > Flashcards

3 Enamel Tissue Flashcards

1
Q

T/F: Enamel, like the other mineralized tissues, contains collagen fibers.

A

False. Enamel contains unique proteins, but does not contain the collagen protein.

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2
Q

Enamel, unlike both dentin and cementum, contains which of the following substances? a. Water b. Collagen c. Amelogenin d. Hydroxyapatite

A

C. Amelogenin is a protein unique to enamel. Enamel is the only mineralized tissue that does not contain collagen.

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3
Q

What percentage of enamel is water?

A

3% water 1% organic substance 96% inorganic substance

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4
Q

T/F: 3% of enamel is composed of organic substance.

A

False. 3% water 1% organic substance 96% inorganic substance

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5
Q

T/F: Enamel contains blood vessels that supply tissue fluid to keep the hydroxyapatite crystals wet.

A

False. Enamel is avascular. This is also true for dentin and cementum.

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6
Q

The highest percentage of enamel is which of the following? a. Amelogenin b. Water c. Hydroxyapatite d. Collagen

A

C, Inorganic is 96% of total.

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7
Q

Hydroxyapatite crystals are most dense in which of the following enamel sites? a. Enamel sheath b. Interrod substance c. Rod core d. Enamel tuft

A

C

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8
Q

Which of the following enamel structures is hypomineralized? a. Enamel rod b. Enamel sheath c. Enamel lamella d. Interrod substance

A

C. Originates at surface of enamel and moves inward. A developmental fault.

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9
Q

Which of the following are described as alternating light and dark bands caused by different direction of enamel rods in adjacent levels? a. Enamel tufts b. Enamel lamellae c. Retzius lines d. Hunter-Schreager bands

A

D

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10
Q

Which of the following enamel structures is described as hypomineralized and originating at the DEJ? a. Enamel lamella b. Enamel spindle c. Line of Retzius d. Enamel tuft

A

D

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11
Q

What enamel structure is described as hypomineralized, originates in the dentin, and crosses the DEJ into the enamel? a. Enamel tuft b. Enamel lamella c. Perikymata d. Enamel spindle

A

D. It’s the end of an odontoblastic process that becomes surrounded by enamel during initial stages of amelogenesis.

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12
Q

Which of the following tissues DO NOT contain both collagen and crystals? a. Enamel b. Dentin c. Primary cementum d. Secondary cementum

A

A. Enamel contains crystals, but not collagen.

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13
Q

The least percentage of enamel is composed of which of the following? a. Water b. Hydroxyapatite c. Calcium d. Organic substance – unique enamel proteins

A

D. Organic substance is than 1% of total. About 90% of this total is a unique enamel protein called amelogenin.

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14
Q

Which of the following is the hardest tissue in the body? a. Bone b. Dentin c. Cementum d. Enamel

A

D. Enamel is the hardest of the 4 mineralized tissues. Hydroxyapatite crystals make up 96% of the enamel’s volume.

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15
Q

Which of the following cells is a specialized epithelial cell? a. Odontoblast b. Cementoblast c. Osteoblast d. Ameloblast

A

D. Ameloblast is a specialized epithelial cell that secretes enamel. The other three mineralized tissues are formed by specialized CT cells.

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16
Q

Which of the following changes occur to enamel due to aging? (More than one correct answer.) a. Decreased resistance to caries. b. Increased discoloration c. Attrition d. Decreased hardness

A

A. NO! Increase resistance to caries, due to fluoride ions. B. Yes, becomes darker with age due to uptake of intrinsic and extrninsic stains. C. Yes, the mechanical wearing away of the enamel surface due to mastication. An unpreventable, normal occurrence. D. NO! Increases in hardness with age from uptake of calcium ions from saliva.

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17
Q
A 
Mottled enamel (mottling = irregular pattern of color)
aka Endemic Dental Fluorosis

Caused by overexposure to fluorine during tooth development (critical period between 1-4 years old)

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18
Q
A

Amelogenesis Imperfecta (imperfect enamel formation)

Rare genetic disorder leading to teeth that are small, abnormal in color, and prone to caries.

Caused by mutations in genes that code for proteins involved in the formation of enamel. These proteins, which are essential for normal enamel development, are either malformed and poorly functioning or missing; this leads to abnormaly thin, soft, and discolored enamel.

Incidence in US; 1 in 14000

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19
Q
A
  1. Enamel
  2. Dentin
  3. Pulp chamber
  4. Root canal
  5. Cementum
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20
Q
A

1/Top: Cementoenamel (CEJ) junction

  1. Dentinoenamel (DEJ) junction
  2. Retzius line
21
Q
A

Retzius line

22
Q
A

Enamel rod

23
Q
A
  1. Rod sheath
  2. Interrod substance
24
Q

Identify dark sites.

A

Enamel rods.

25
Q
A

Enamel lamella (?)

26
Q
A

Enamel lamella

27
Q
A

Enamel tuft

28
Q

Identify light/dark areas marked by arrows.

A

Hunter-Schreager bands

29
Q
A

Enamel spindle (cell process of odontoblast)

30
Q
A

1/Top: Cementoenamel Junction (CEJ)

2/left: Retzius line

3/right: Dentinoenamel junction (DEJ)

31
Q
A
  1. Retzius line
  2. Hunter-Schreger bands
32
Q
A

Retzius line

33
Q
A

1/Top: enamel rod

  1. Interrod striation
34
Q
A

1/Top: Enamel rod

  1. Interrod substance
35
Q
A

Interrod substance

36
Q
A

Enamel rod (with interrod substance)

37
Q
A

Enamel lamella

38
Q
A

Enamel tuft

39
Q
A

Enamel spindle

40
Q
A
  1. Odontoblastic process
  2. Enamel spindle
41
Q
A

Retzius line

42
Q
A
  1. Enamel lamella
  2. Enamel tuft
  3. Enamel spindle
43
Q
A
  1. Enamel lamella (originates at enamel surface)
  2. Enamel tuft (originates at DEJ)
44
Q
A

1/Top. Enamel spindle

  1. Retzius line
  2. Hunter-Schreger bands
45
Q
A
  1. Odontoblastic process
  2. Enamel spindle
46
Q
A

All enamel rods (LR shows Hunter-Schreager bands?)

47
Q
A

UL is enamel tissue.

UR is dentin tissue.

LL is pulp tissue.

LR is cementum tissue.

48
Q
A
  1. Predentin
  2. Mineralized dentin
  3. Enamel matrix. Ameloblast are along the outer surface of enamel
49
Q
A

UL: Enamel rods, cross-section
UR: Enamel rods, longitudinal section
LL: Enamel rods, longitudinal section
LR: Hunter-Schreager bands – rod directions

Oral Histology (9 decks)

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