In this Post, You will cover MCQ on Enamel (Dental Histology). If you have not read about Enamel then first read in textbooks or on our website with notes (Click Here) or you can try our videos to understand easy. (Click Here)..If you want textbooks for free then click here
1. On the cusps of human molars and premolars, maximum thickness of enamel is about:
A. 0 to 1 mm
B. 2 to 3 mm
C. 4 to 5 mm
D. 4 to 6 mm
1. On the cusps of human molars and premolars, maximum thickness of enamel is about:
A. 0 to 1 mm
B. 2 to 3 mm
C. 4 to 5 mm
D. 4 to 6 mm
2. The specific gravity of enamel is:
A. 2.4
B. 2.6
C. 2.8
D. 3.0
3. Which of the following statements is/are true?
A. Enamel acts like a semipermeable membrane
B. Enamel mainly consists of inorganic material (96%) and small amount of organic substance and water (4%)
C. During development histologic staining reactions of Enamel matrix resemble keratinizing epidermis
D. All of the above
4. Which of the following statements is/are true?
A. Enamel is composed of enamel rods, rod sheath and interprismatic substances
B. The number of enamel rods is about 5 million in lower lateral incisors and 12 million in the upper first molar
C. The length of enamel rods is greater than thickness of enamel because of oblique direction and wavy course of the rods.
D. All of the above
5. The diameter of the enamel rods increases from dentino-enamel junction towards the surface of enamel in a ratio of about:
A. 1:2
B. 1:3
C. 1:4
D. 1:5
6. In cross sections of human enamel, many rods resemble:
A. Triangle
B. Fish scales
C. Skin scales
D. Cow horn
7. Which of the following statements is/are false?
A. The average thickness of the crystal of human enamel is about 30 nanometers
B. The average width of the crystal of human enamel is about 90 nanometer
C. Both of the above
D. None of the above
8. The striations are more pronounced in enamel that is:
A. Sufficiently calcified
B. Insufficiently calcified
C. Fully calcified
D. Not at all calcified
9. The enamel rods are segmented because the enamel matrix is formed in rhythmic manner. In humans these segments seem to be of a uniform length of about:
A. 2 microns
B. 4 microns
C. 6 microns
D. 8 microns
10. The arrangement of enamel rods in the permanent teeth, in the cervical region, deviates from the horizontal in an:
A. Apical direction
B. Occlusal direction
C. Incisal direction
D. All of the above
11. In an oblique plane the bundles of rods seem to intertwine more irregularly in the region of cusps
or incisal edge, this optical appearance of enamel is called:
A. Gnarled enamel
B. Striation
C. Hunter- Schreger bands
D. Incremental lines of Retzius
12. The change in the direction of enamel rods is responsible for appearance of the:
A. Gnarled enamel
B. Hunter-Schreger bands
C. Both of the above
D. None of the above
13. The Brownish bands i.e. the successive apposition of layer of enamel during the formation of crown is known as:
A. Gnarled enamel
B. Incremental line of Retzius
C. Hunter-Schreger bands
D. All of the above
14. In transverse sections of a tooth, the incremental line of Retzius appears as:
A. Concentric circle
B. Oblique line
C. Zigzag line
D. Cracks
15. Perikymata are transverse, wave-like grooves, believed to be the external manifestation of the:
A. Striae of Retzius
B. Gnarled enamel
C. Hunter-Schreger bands
D. All of the above
16. Perikymata are absent in the:
A. Postnatal cervical part
B. All permanent teeth
C. All deciduous teeth
D. Occlusal part of the deciduous teeth
17. The enamel of deciduous teeth develops partly before and partly after birth, the boundary between
the two portions is known as:
A. Basal lamina
B. Incremental line
C. Neonatal line
D. Postnatal line
18. A delicate membrane which covers the entire crown of the newly erupted tooth is called as:
A. Primary enamel cuticle
B. Nasmyth’s membrane
C. Pellicle
D. Both (a) and (b)
19. Thin, leaf-like structures that extend from enamel surface towards the dentino-enamel junction are called:
A. Enamel tufts
B. Gnarled enamel
C. Enamel lamellae
D. Enamel spindle
20. Which of the following statements is/are true about enamel lamellae?
A. Type A lamellae are composed of poorly calcified rod segments
B. Type B lamellae consist of degenerated cells
C. Type C lamellae arise in erupted teeth where cracks are filled with organic matter (more common)
D. All of the above
21. Enamel tufts which arise at the dentinoenamel junction and reach into enamel to about 1/5th to 1/ 3rd of its thickness are:
A. Hypocalcified enamel rods and interprismatic substances
B. Hypercalcified enamel rods only
C. Hypomineralized enamel rods only
D. Similar to surface structures
22. In the mature dental tissues, the only tissue whose cells are lost is:
A. Dentin
B. Pulp
C. Cementum
D. Enamel
23. Which statement about enamel prism rod is not correct?
A. The prisms run from the dentinoenamel junction to the crown surface
B. The maximal width of a prism in horizontal section is 5 μm
C. Prisms are wider near the dentinoenamel junction than near the crown surface
D. The lengths of all enamel prisms are equal
24. The enamel organ:
A. Promotes the differentiation of the dental papilla
B. Does not form the enamel
C. Does not narrow after the first layer of dentin has formed
D. Does not promote the differentiation of the dentin
25. After the enamel is completely formed and has undergone maturation:
A. The ameloblasts form the primary enamel cuticle
B. The ameloblasts become much longer
C. The enamel organ becomes a widened layer of stratified squamous epithelium
D. None of the above
26. During enamel maturation:
A. Calcification ceases
B. Additional calcification occurs until complete calcification is present
C. The ameloblasts play no role
D. Additional enamel matrix is produced
27. The maturation of the enamel starts at:
A. Any point between occlusal surface and cervical region
B. Occlusal surface of the crown and progresses toward cervical region
C. Cervical region of the crown
D. None of the above
28. The formation of dentin:
A. Decreases the blood supply
B. Is not based on tissue interdependence
C. Is apparently a necessary stimulus for the formation of enamel
D. Is not a necessary stimulus for the formation of enamel
29. The perikymata are:
A. Elevations between the imbrication lines of Pickerill
B. Present in the cementum
C. Present in the enamel
D. Present in the dentin
30. The incremental lines of Retzius are seen in ground transverse sections:
A. As white bands not in concentric rings
B. As brown bands not in concentric rings
C. As concentric circles in the enamel which resemble rings in a tree trunk
D. Running inward from the dentinoenamel junction
31. The enamel rod sheath:
A. Has cross striations
B. Has a lesser amount of inorganic matter than the enamel rod
C. Is a more calcified enamel peripheral shell around each enamel rod
D. None of the above
32. The enamel rods in the incisal and cuspal areas are:
A. Vertical in direction
B. Horizontal in direction
C. Inclined apically
D. Oblique and then horizontal in direction
33. Enamel rods:
A. Have only a concave surface in cross section
B. Increase in thickness from the dentinoenamel junction to the surface of enamel
C. Are always the same thickness regardless of location
D. Decrease in thickness from the dentinoenamel junction to the enamel surface
34. Gnarled enamel is:
A. Present only at the cementoenamel junction
B. Present only at the dentinoenamel junction
C. Present only in deciduous teeth
D. Due to markedly wavy and irregular enamel rods at the cusps or incisal edges
35. Ionic interchanges between matured/erupted enamel and saliva:
A. Occur throughout life
B. Occur only for two years following eruption
C. Cease to occur in young adult life
D. Do not occur
36. Matured enamel is subjected to:
A. Erosion and attrition only
B. Caries, erosion and attrition
C. Caries and attrition only
D. Caries and erosion only
37. Enamel contains:
A. 96% organic substance
B. 1.5% inorganic substance
C. 100% organic substance
D. None of the above
38. Enamel contains:
A. 96% water
B. 1% water
C. 5% water
D. None of the above
39. Enamel is:
A. The only tissue whose formation does not cease
B. Made up of 100% inorganic material
C. The only calcified tissue in mammals of epithelial origin
D. None of the above
40. Enamel lamellae:
A. Are club-like swellings extending into the enamel for short distance
B. Extend for short distances from the dentinoenamel junction toward the enamel surface
C. Represent a pathway for proteolytic bacteria to the dentinoenamel junction
D. Contain less organic matter than the enamel proper
41. Enamel tufts:
A. Form a pathway for proteolytic bacteria to extend to the dentinoenamel junction
B. Contain less organic material than normal enamel
C. Contain highly calcified enamel rods and interprismatic substance
D. Are areas of imperfect calcification extending for short distances from the dentinoenamel junction toward the enamel surface
42. The Hunter-Schreger bands are:
A. Not visible in ground sections
B. An illusion in reflected light
C. Due to alternating directions of successive groups of enamel rods in reflected light
D. Not visible in reflected light
43. The uptake of fluorine by enamel:
A. Fails to taper off
B. Is the same during the first years following enamel formation and in later years
C. Is very slow during the first years following enamel formation
D. Is very rapid during the first years following enamel formation
44. Nitrogen is present in the surface enamel in:
A. Greater concentration in young teeth
B. Greater concentration in older teeth
C. Lower concentration in older teeth
D. Lower concentration at the dentinoenamel junction
45. The addition of 1 PPM of fluorine (F) to the drinking water causes:
A. An increment of about 300 PPM in surface enamel
B. A decrement of about 100 PPM in surface enamel
C. An increase in aluminum in the surface enamel
D. No change in F concentration in surface enamel
46. The principal blood supply of ameloblasts during most of enamel formation is from:
A. Enamel
B. Dental pulp
C. Reduced dental organ
D. Dentin
47. In cross section enamel prisms approximately have an average thickness of:
A. 3 microns
B. 300 angstroms
C. 3 angstroms
D. 30 microns
48. The long axis of enamel crystals is:
A. Parallel to the prism axis
B. Parallel to the tooth surface
C. Perpendicular to the tooth surface
D. Both (a) and (c)
49. The gnarled enamel is observed in:
A. In cervical area
B. Only in the canines
C. In carious areas
D. In cuspal areas
50. The enamel spindle is:
A. Part of Tomes’ enamel process
B. The distal part of an odontoblastic process in enamel
C. An area with a high collagen content
D. A hypercalcified area
51. Hunter Schreger bands appear due to:
A. Daily growth rhythms
B. Increased organic content in some areas
C. Dietary change after birth
D. Changes in the enamel prism orientation from one group of prisms to the next group of prisms
52. Tomes’ enamel process:
A. Remains in the mature enamel as the ameloblastic process
B. Extends into the dentin
C. Forms at the proximal end of the ameloblast
D. Is apical to the terminal bar/area at the secretory apical end of ameloblast
53. Enamel that can withstand severe masticatory force is:
A. Root enamel
B. Cervical enamel
C. Gnarled enamel
D. Enamel lamellae.
54. Poorly calcified enamel is present in:
A. Perikymata
B. Gnarled enamel
C. Enamel lamellae
D. Enamel prisms.
55. In the human body the hardest calcified tissue is:
A. Dentin
B. Cementum
C. Bone
D. Enamel
56. The percentage of the inorganic component of the enamel is:
A. 96%
B. 95%
C. 92%
D. 90%
57. The dentinoenamel junction is in the form of:
A. A scalloped line with convexities towards the enamel.
B. A scalloped line with the convexities of the scallops towards dentin
C. A straight line
D. None of the above.
58. Direction of the enamel rods in the deciduous and permanent teeth is:
A. Same throughout
B. Different at cervical third
C. Different at occlusal and incisal thirds
D. None of the above
59. For the control of dental caries fluoride level in drinking water should be:
A. 8 PPM
B. 4 PPM
C. 2 PPM
D. 1 PPM
60. Enamel tufts:
A. Arise from the surface of enamel and reach at dentinoenamel junction
B. Arise at the dentinoenamel junction and proceed into the enamel towards surface
C. Arise at dentin pulp junction and reach upto enamel
D. Arise from the surface of enamel and reach upto the pulp.
61. The angle between the diazones and parazones is approximately:
A. 10 degree
B. 40 degree
C. 70 degree
D. 100 degree
62. The mean rate of enamel formation is:
A. 1.0 micron per day
B. 3. 5 micron per day
C. 6. 5 micron per day
D. 10.0 micron per day
63. Which of the following is present at dentinoenamel junction and help in cell signaling?
A. Ameloblastin
B. Enamelin
C. Tuftelin
D. None of the above
64. In transition stage following changes take place:
A. Reduced hight of ameloblast
B. Secretion of enamel stops completely
C. Removal of amelogenin starts
D. All of the above
65. What is the thickness of the layer of prismless enamel found in primary teeth?
A. 25 microns
B. 50 microns
C. 75 microns
D. 100 microns
66. The hardest calcified tissue in human body is
(a) Bone
(b) Cementum
(c) Enamel
(d) Dentin
67. The thickness of enamel is
(a) Greatest at the buccal surface
(b) Greatest at the lingual surface
(c) Greatest at the cusp tip
(d) Uniform
68. The maximum thickness of the enamel at the cusp of molars and premolars is
(a) 1–1.5 mm
(b) 2–2.5 mm
(c) 3 mm
(d) 3.5 mm
69. The inorganic content in enamel is
(a) 90%
(b) 96%
(c) 95%
(d) 92%
70. The diameter of enamel rods averages at
(a) 2 μm
(b) 3 μm
(c) 4 μm
(d) 6 μm
71. The direction of enamel rods in a permanent tooth is
(a) Vertical at the cusp tip
(b) Tangential to the outer enamel surface
(c) Horizontal in the cervical region
(d) All of the above
72. Gnarled enamel is
(a) Enamel formed due to deficiency
(b) Optical appearance of enamel due to its wavy course
(c) Enamel present at the furcation of teeth
(d) None of the above
73. The alternate dark and light strips of varying width seen in the longitudinal ground section under reflected light are
(a) Dental bands
(b) Perikymata
(c) Incremental lines
(d) Hunter–Schreger bands
74. External manifestation of striae of Retzius are
(a) Enamel cracks
(b) Rods
(c) Perikymata
(d) None of the above
75. The direction of the enamel rods at the cervical region is
(a) Horizontal
(b) Vertical
(c) Oblique
(d) None of the above
76. The _______ extends over the full thickness of enamel from DEJ
(a) Enamel lamella
(b) Enamel spindles
(c) Enamel tufts
(d) None of the above
77. The dentinoenamel junction is a
(a) Straight line
(b) Scalloped line with convexities towards dentin
(c) Scalloped line with concavities towards dentin
(d) None of the above
78. Odontoblastic processes which pass into the enamel through the dentinoenamel junction are called
(a) Enamel tufts
(b) Perikymata
(c) Enamel spindles
(d) Enamel extensions
79. All are hypomineralized except
(a) Enamel spindles and tufts
(b) Enamel lamellae and tufts
(c) Enamel prism and surface layer
(d) Neonatal line of Retzius
80. Which is true about enamel prisms?
(a) They are arranged perpendicular to the enamel surface
(b) They show a keyhole pattern on cross-section
(c) They are apatite crystals arranged parallel to the long axis of the body
(d) All of the above
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