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Practice MCQ > Enamel > Flashcards

Enamel Flashcards

1
Q

What is the prismatic structure of enamel is due to?

A

variation in crystal orientation

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2
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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3
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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4
Q

Organic components of enamel are primarily removed from enamel by what?

A

Maturative ameloblasts

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5
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.

A

B

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6
Q

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.

A

C

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7
Q

The primary enamel cuticle is formed by the what?

A

Ameloblasts after the enamel has been completed

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8
Q

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

A

D

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9
Q

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.

A

C

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10
Q 
Which of the following is poorly calcified enamel?
a- Gnarled enamel.
b- True enamel lamellae.
c- Perikymata and gnarled enamel.
d- Interprismatic substance.
A

B

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11
Q

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.

A

B

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12
Q

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.

A

D

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13
Q

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.

A

C

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14
Q 
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.
A

C

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15
Q

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.

A

D

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16
Q 
All of the following structures in enamel are ectodermal origin except:
a- Enamel spindle.
b- Enamel prisms.
c- Enamel lamellae (type A).
d- Enamel tufts.
A

A

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17
Q

The peripheral part of the E rod is called:

a. Interrod region
b. Rod sheath.
c. Rod region.
d. Key hole.

A

B

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18
Q

Concerning the rod sheath, one of the following statement is incorrect:

a. It occupies the peripheral part of the E. rod.
b. It forms the border where crystals of the rod and interrod enamel meet.
c. It is highly calcified than the rod.
d. It has a higher organic content thus resists decalcification more than the rod.

A

C

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19
Q 
perikymata are the external surface manifestations of:
A. Enamel rods
B. Incremental lines of retzius
C. Nasmyth's membrane
D. Pellicle
A

B

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20
Q 
The percentage of inorganic matter in fully developed enamel is about
A. 66%
B. 76%
C. 86%
D. 96%
A

D

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21
Q 
The enamel of the posterior teeth is thickest at:
A, Cervical third of buccal surface
B. Middle third of buccal surface
C. Middle third of lingual surface
D. Occlusal surface
A

D

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22
Q

Hunter Schreger band are:
A. Dark and light bands of enamel seen in longitudinal ground section
B. Dark and light bands of enamel seen in horizontal ground section
C. Dark and light brands of dentin seen in longitudinal section
D. Dark and light bands of dentin seen in horizontal

A

A

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23
Q

Enamel tufts are:
A. Thin tuft like structure extending from enamel surface of dentin enamel junction
B. Tuft like structure arising from dentin-enamel junction towards enamel surface
C. Odontoblastic processes extending into D. None of the above

A

B

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24
Q 
Following is not an external manifestation of enamel
A. Enamel tufts
B. Enamel lamella
C. Incremental lines of enamel
D. Enamel cuticle
A

A

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25
Q

Blunt cell processes seen on the developing ameloblasts are celled as:
A. Tomes fibres
B. Tomes layer
C. Tomes D. Odontoblastic processes

A

A

26
Q 
Interwining of the enamel rods at the cusp timps and the incisal edges of a tooth is called:
A. Enamel spindles
B. Gnarled enamel
C. Incremental lies of woven
D. Incremental lines of retzius
A

B

27
Q 
Incremental lines of retzius are seen in:
A. Enamel
B. Dentin
C. Cementum
D. Pulp
A

A

28
Q 
All are true regarding the enamel spindles except:
A. Produced by ameloblasts
B. Found in the region of cusps
C. Surrounded by inter prismatic enamel
D. Terminate as rounded process
A

A

29
Q

Ionic exchange between enamel surface and environment
A. Does not take place once enamel surface and einvironment
b. stops after 2 years of eruption
C. Continues till adult life
D. Continues through out life

A

D

30
Q 
Approximately how many enamel rods will be present in a maxillary molar?
A. 5 million
B. 7 million
C. 9 million
D. 12 million
A

D

31
Q

All are true about the striae of retzius except:
A. Constitute the rest lines with in the enamel rods
B. Have high inorganic content
C. They are areas of increased porosity
D. Allow the movement of water and small ions

A

B

32
Q

Neonatal lines are found in all of the following except:
A. Enamel of primary incisors
B. Enamel of permanent canines
C. Enamel and dentin of permanent first molars
D. Dentin of permanent mandibular incisors

A

B

33
Q 
Which of the following structures is not of ectodermal origin:
A. Hunter schreger bands
B. Enamel spindles
C. Enamel tufts
D. Enamel lamellae
A

B

34
Q 
The formative cells of which of the following dental tissues disappear once tissue is formed
A. Enamel
B. Dentin
C. Periodontal ligament
D. Cementum
A

A

35
Q 
Which of the following tissues have no reparative capacity:
A. Enamel
B. Dentin
C. Cementum
D. Periodontal ligament
A

A

36
Q

The enamel has no capacity of self repair because
A. It has only a small percent of organic content
B. Its formative cells are lost once it is completely formed
C. It is essentially a keratin tissue and has no blood vessels
D. It has no direct connection with the active cells of the dental pulp

A

B

37
Q 
calcification in enamel starts at:
A. Enamel matrix
B. Root
C. CEJ
D. DEJ
A

D

38
Q 
Inorganic content of enamel is about:
A. 35%
B. 50%
C. 4%
D. 96%
A

D

39
Q 
Length of enamel rods is:
A. Greater than the thickness of enamel
B. Less than the thickness of enamel
C. Equal to the thickness of enamel
D. None of the above
A

A

40
Q 
The diameter of the rod is:
A. 4 μ m
B. 9 μ m
C. 7 μ m
D. 2 μ m
A

A

41
Q

True about direction of enamel rods:
A. They originate at right angle to dentin surface
B. They are almost vertical near the incisal edge (or) cusp tip areas
C. In the cervical third of deciduous crowns they are almost horizontal in direction
D. In cervical region of permanent teeth, they deviate in apical direction
E. All of the above

A

E

42
Q 
Thin leaf like structures that extend from enamel surface in to DEJ are:
A. Enamel spindles
B. Enamel lamella
C. Enamel tufts
D. Perikymata
A

B

43
Q

Dentino enamel junction is:
A. Non-scalloped
B. Straight
C. Scalloped and the convexities are directed towards dentin
D. Scalloped and the convexities are directed towards enamel

A

C

44
Q 
Hertwig’s root sheath is formed from:
A. Stratum inter medium
B. Stellate reticulum
C. Outer enamel epithelium
D. Cervical loop
A

D

45
Q

Which of the following is correct:
A. Each rod is formed by 4 ameloblasts
B. Each ameloblast contributes to 4 different rods
C. Head of the rod is formed by one ameloblasts, and tail is formed by three other ameloblasts
D. All of the above

A

D

46
Q

The striking difference between enamel and other mineralized tissues is
A. Presence of high percentage of organic matrix
B. Presence of incremental lines
C. Enamel has high reparative capacity
D. Most of organic component is lost during mineralization

A

D

47
Q 
Synthesis of enamel matrix proteins occurs in the:
A, Outer enamel epithelium
B.  Ameloblast
C. Stratum intermedium
D. Stratum granulosum
A

B

48
Q 
Among the following the structure that is most calcified is:
A. Enamel lamella
B. Enamel rod
C. Enamel spindle
D. Enamel tuft
A

B

49
Q 
Enamel spindles are formed by:
A. Cracks
B. Ameloblasts
C. Odontoblasts
D.Hypocalcified rods
A

C

50
Q 
Neonatal line is also referred to as:
A. Retzius line
B. Line of cross striations
C. Incremental lines
D. Line of enamel tufts
A

C

51
Q

Incremental lines of Retzius appear
A. As lines in the enamel running at right angles to the enamel surface
B. As lines in the dentin running at right angles to the dentino-enamel junction
C. In enamel and follow the apposition pattern
D. In dentin and follow the appositional pattern

A

C

52
Q 
Nutritional supply of the ameloblasts during most of their life cycle is from the:
A. Dental pulp
B. Odontoblastic processes
C. Dental sac
D. Reduced dental organ
A

C

53
Q 
Enamel rods at the cervical area at the occlusal edge and incisal lip in permanent teeth are:
A. Straight
B. Shallow
C. Bent
D. Curved
A

C

54
Q

The thickness of prismless enamel in diciduous teeth is:

25 μ m
50 μ m
75 μ m
100 μ m

A

A

55
Q

Gnarled enamel is seen in:

Proximal surface of tooth
Cervical region of tooth
Cusp tips of tooth
All of the above

A

C

56
Q

Neonatal lines are seen in:

A. Enamel of deciduous incisiors
B. Enamel of permanent incisors
C. Enamel of premolars
D. Dentin of all teeth, as if is formed first

A

A

57
Q

Which of these DOES NOT contain collagen

A. Enamel
B. Dentin
C. Bone
D. Cementum

A

A

58
Q

The average width of enamel rods is:

A. 10mm
B, 5mm
C. 2mm
D. 0.5mm

A

B

59
Q

Maximum amount of phosphate is seen in:

A. Bone
B. Enamel
C. Gingiva
D. Dentin

A

B

60
Q

Dark bonds that are present in enamel rods at intervals of 4 μms are:

A. Neonantal bands
B. Cross striations
C. Striae of Retzius
D. Hunter-Schregar bands

A

B

61
Q

Enamel can act in a sense like a:

A. Permeable membrane
B. Impermeable membrane
C. Semipermeable membrane
D. Infrapermeable membrane

A

C

62
Q

Non acidic, nonionic protein which helps in enamel mineralization

Tuftelin
Sheathlin
Enamelin
Amelogenin

A

D

Practice MCQ (7 decks)

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