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Enamel Flashcards

1
Q

Ameloblasts having ruffled borders are:
a- Secretory ameloblasts.
b- Maturative ameloblasts.
c- Protective ameloblasts.
d- Transitional ameloblasts.

A

B

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2
Q

Which of the following is not a feature of enamel?
a- Contour lines of Owen.
b- Cross striations.
c- Prism sheath.
d- Perikymata.

A

A

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3
Q

Maturative ameloblasts are characterized by having:
a- A distally positioned nucleus.
b- A highly basophilic cytoplasm.
c- A highly-developed Golgi complex.
d-A distal cell membrane with many infoldings.

A

D

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4
Q

Which of the following does not occur during maturation of enamel?
a- Influx of calcium and phosphorus.
b- Growth of hydroxyapatite crystals.
c- Increase in organic content.
d-Decrease in the water content.

A

C

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5
Q

Incremental lines are a result of variation in:
a- Proliferation.
b- Histodifferentiation.
c- Morphodifferentiation.
d- Rhythmic apposition.

A

D

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6
Q

The prismatic structure of enamel is due to:
a- Variation in the density of organic material.
b- Variation in crystal orientation.
c- A rhythmic pattern of apposition.
d- The periodic change in prism direction.

A

B

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7
Q

The prismless layer of enamel:
a- Is found only in primary teeth.
b- Does not contain prism & prism sheaths.
c- Is found near the amelo-dentinal junction.
d- Contains no hydroxyapatite.

A

B

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8
Q

Enamel tufts:
a- Contain cellular processes.
b- Can pass to dentin.
c- Are seen in decalcified sections.
d- Are grass like structure.

A

D

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9
Q

During the maturation stage of enamel formation, which of the following does not occur in the ameloblastic layer?
a- Water absorption.
b- Protein absorption.
c- Change in cellular organelles.
d- Secretion of enamel matrix.

A

D

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10
Q

When prismless enamel is formed, the secretory ameloblast does not contain:
a- Rough endoplasmic reticulum.
b- Tome’s process.
c- Nucleus.
d- Secretory granules.

A

B

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11
Q

Which of the following is true:
a- Enamel is the weakly mineralized tissue.
b- Enamel is the highly mineralized tissue
c- Enamel is the highly permeable tissue.
d-Enamel is a non brittle tissue.

A

B

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12
Q

Neonatal lines are present in:
a- All permanent teeth.
b- Permanent canines.
c- All deciduous & first permanent molar.
d- Premolars.

A

C

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13
Q

Organic components of enamel are primarily removed from enamel by:
a- Secretory ameloblasts.
b- Maturative ameloblasts.
c- Transitional ameloblasts.
d- Enamel spindle.

A

B

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14
Q

The main difference between the rod and the interrod region is:
a- Crystal size.
b- Crystal orientation.
c- Crystal composition.
d- In the nature of the organic component.

A

B

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15
Q

The striae of Retzius:
a- Are parallel to the enamel rods.
b- Are parallel to the surface of the enamel in the cervical region.
c- Are not seen in the cuspal one third of the enamel.
d- Would be seen as concentric rings in a horizontal section of the crown.

A

D

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16
Q

Enamel is composed of:
a) Rod, interrod & rod sheath.
b) Only enamel prisms.
c) Needle shaped crystals.
d) Prism sheath.

A

A

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17
Q

The extensions from secretory ameloblast cells that give structure to enamel rods are called:
a) Enamel tuft.
b) Tomes processes.
c) Enamel spindles.
d) Enamel lamellae.

A

B

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18
Q

Striae of Retzius:
a) Result from enamel crack.
b) Separate prenatal from postnatal enamel.
c) Are due to rhythmic apposition of enamel.
d) Are hypermineralized structure.

A

C

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19
Q

Enamel Rods:
a) Their number varies in different teeth.
b) Have an average width of 1um.
c) Are Present at the enamel surface.
d) Have a straight course at the cusps of teeth.

A

A

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20
Q

Enamel is formed of:
a- 76% minerals & 24% organic materials and water.
b- 96% minerals & 4% organic materials and water.
c- 86% minerals & 14% organic materials and water.
d- 99% minerals & 1% organic materials and water.

21
Q

which of the following is absent in all premolars:
a- Enamel spindle.
b- Enamel tuft.
c- Neonatal line.
d- Enamel lamella.

22
Q

Cross striations in enamel:
a- Are an optical phenomena.
b- Result from abrupt change in environment before and after birth.
c- Result from mineralization disorder.
d- Appear to be periodic bands at 4 microns interval across the rod.

23
Q

The prism sheath:
a- Is a dense continuous sheath separating rod from inter-rod.
b- Result from abrupt change in crystals orientation.
c- Is more mineralized than rod and inter-rod.
d- Found in prismless enamel

24
Q

The complex arrangement of rods over the cusps of teeth is termed:
a- Prismless enamel.
b- Gnarled enamel.
c- Prenatal enamel.
d- Postnatal enamel.

25
The origin of enamel is: a- neural crest cells b- Ectoderm. c- Mesoderm. d- Ectomesenchyme.
B
26
Hypocalcified areas in enamel are: a- Enamel spindles. b- Dentino-enamel junction. c- Interprismatic substances. d- Enamel tufts.
B & D ( if you have to choose one answer, go with D)
27
Prismless enamel: a- Is less mineralized than prismatic enamel. b- Is found only in the cervical area of permanent teeth. c- Is harder than prismatic enamel. d- Found near the dentino-enamel junction.
C
28
The perikymata: a- Is an optical phenomena resulting from changes in direction of enamel rods. b- Is a highly mineralized outer enamel surface. c- Is formed of transverse grooves, represents an outer manifestation of brown stria of Retzius. d- Found at the cusp tip.
C
29
What is the result of cracks before tooth eruption: a- Enamel lamella type A. b- Enamel lamella type B. c- Enamel lamella type C. d- Enamel tufts.
B
30
The primary enamel cuticle is formed by the: a- Outer dental epithelium. b- Ameloblasts just before tooth eruption. c- Fusion of oral epithelium and reduced enamel epithelium. d- Ameloblasts after the enamel has been completed.
D
31
The surface enamel: a- Is similar to the subsurface enamel. b- Is softer than subsurface enamel. c- Contains less mineral than subsurface enamel. d- Highly mineralized than subssurface enamel.
D
32
The prism sheath: a- Is a continuous sheath. b- Is more calcified than the enamel rod. c- Is less calcified than the enamel rod. d- Is equally calcified when compared to the enamel rod.
C
33
The predominant inorganic portion of enamel is: a- Calcium. b- Carbonate. c- Phosphate. d- Fluoride.
A
34
Incremental lines of Retzius form grooves on the surface of the enamel termed: a- Perikymata. b- Neonatal lines. c- Gnarled enamel. d- Enamel cuticle
A
35
Which of the following is poorly calcified enamel? a- Gnarled enamel. b- True enamel lamellae. c- Perikymata and gnarled enamel. d- Interprismatic substance.
B
36
The cross striations characteristic of enamel rods represent: a- Incremental growth pattern. b- The junctional complex of ameloblasts. c- Hunter-Schreger bands. d- The inter rod region.
A
37
Enamel spindles: a- Are areas of prismatic enamel. b- Are present at the occlusal surfaces of enamel. c- Are the terminal ends of odontoblastic processes. d- Are located at the cemento-enamel junction.
C
38
Which of the following is a true statement about the organic matrix of the newly synthesized enamel? a- It represents 30% by weight of the organic content. b- It has a high content of amelogenins. c- It contains collagen fibers. d- It has a high inorganic content.
B
39
Tome's processes: a- Contain mitochondria, but lack Golgi saccules and rough endoplasmic reticulum. b- Lack secretory granules. c- Indent the immature enamel to produce a serrated outline on its appositional surface. d- Are located at the proximal end of the ameloblast.
C
40
Which of the following is the source of nutrient supply to the secretory ameloblasts during early crown formation? a- Subodontoblastic plexus of capillaries. b- Central blood vessels in the dental papilla. c- Dental sac capillaries adjacent to the epithelial diaphragm. d- Dental sac capillaries adjacent to the outer dental epithelium.
D
41
Enamel spindles are formed by: a- Odontoblastic process. b- Ameloblastic process. c- Hypocalcified rods. d- Cracks.
A
42
Neonatal lines are found in all the following except: a- Enamel of primary incisors. b- Enamel of permanent first molar. c- Enamel of permanent second molars. d- Enamel of primary molars.
C
43
Hypocalcified ectodermal structures in enamel are: a- Spindles and lamellae. b- Odontoblastic processes and tufts. c- Tufts and spindles. d- Lamellae type A,and tufts.
D
44
Which of the following most correctly describes the significance of Hunter Schreger bands? a- It indicates variation in size of enamel rods. b- It reflects variations in the length of enamel rods. c- It represents hypercalcified areas in cervical enamel. d- It is an optical effect that is not related to variations in enamel structure.
D
45
The orientation of hydroxyapatite crystals in enamel, the greatest crystal density would be present in: a- enamel lamellae. b- The interrod region. c- The prismless layer. d- Gnarled enamel.
C
46
Perikymata: a- Are oriented parallel to the long axis of the crown (tooth). b- Are surface manifestation of Retzius lines. c- Are only located in prismless enamel. d- Produce the scalloping seen along the DEJ.
B
47
Unmineralized structures seen in the enamel are : a- Cross striations. b- Enamel tufts. c- Incremental lines of Retzius. d- Enamel spindles.
D
48
All of the following statements about the incremental lines of Retzius in enamel are true except: a- They run as concentric lines over the cusp. b- Perikymata are outer manifestations of it. c- They are formed as result of rhythmic apposition. d- They do not reach the cervical region
D
49
Incremental lines of Retzius appear: a- In dentin. b- In enamel. c- In cementum. d- In bone.
B

Practice MCQ (10 decks)

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