Saturday, 5 November 2011

MCQs in ORAL HISTOLOGY Part- 1


M.C.Q. QUESTION

Tooth development

1-Concrescence is:
a- An extra root or accessory roots in a formed tooth.
b- Distorted root or roots in a formed tooth.
c- A union of root structure of two or more teeth through cementum only.
     d- A spherical projection on the cemental root surface.

2- What structure is formed in the crown first?
a-  Enamel.
b- Cementum.
c-  Pulp.
      d- Dentine.

3- Which of the following induces the dental papilla cells to be differentiated into odontoblasts?
a-    Stratum intermedium.
b-   Reduced enamel epithelium.
c-    Inner enamel epithelium.
      d- Outer enamel epithelium.

4- No basal lamina is found between the cells of the:
a-    Stratum intermedium and inner enamel epithelium.
b-   Outer enamel epithelium and the dental sac.
c-    Inner layer of Hertwig's sheath and the dental papilla.
      d- Inner enamel epithelium and the dental papilla.

5- Which of the following is not a functional activity of the enamel organ:
a-    Inducing the differentiation of Odontoblasts.
b-   Secretion of enamel matrix.
c-    Maturation of enamel.
      d- Formation of cementum.

6- Which of the following is not derived from the dental organ:
a-     Stellate reticulum.
b-    Hertwig's epithelial root sheath.
c-     Odontoblasts.
d-    Ameloblasts.



7- The stratum intermedium:
a- Induces dentin formation.
b- Is separated from the stellate reticulum by a basal lamina.
c- Develops in cap stage.
d- Is important for enamel maturation.
     
8- The dental organ
      a- Develops from cells in the dental follicle.
      b- Is a completely connective tissue structure.
      c- Is a completely epithelial structure. 
      d- Is highly vascular, as ameloblasts require an enriched environment.

9- The enamel cord
       a- Is an extension of the dental lamina.
       b-Is an extension of the outer dental epithelium.
       c- Is an extension of successional dental lamina
       d-Extends from the stratum intermedium to the stellate reticulum.

10-Dental follicle cells
a- Differentiate into the ameloblast layer.
b- Differentiate into the odontoblast layer.
c- Are found within the dental organ.
d- Migrate to dentin surface of the root and differentiate into the cementoblast.
                                                                                                                       
11- All of the following is the functions of The Stellate Reticulum except:
a- Keep Space for The enamel development.
b- Act as a reservoir for nutritive materials.
c- Act as a cushioned to protect ameloblasts.
           d- Secretes alkaline phosphatase enzyme.

12- The epithelial root sheath of Hertwig disintegrates:
a- After odontoblastic differentiation & before dentin matrix formation.
b- After odontoblastic differentiation & dentin matrix deposition.
c- Before odontoblastic differentiation.
          d- After cementum formation.

13- All of the following is a function of dental sac except:
a- Nutrition of enamel organ.
b- Formation of cementum.
c- Formation of periodontal ligament.
d- Formation of supporting alveolar bone.





14- The lateral dental lamina gives rise to:
a- Deciduous teeth .
b- Permanent successors.
c- Permanent molars.
d- Vestibular lamina.

15- The stratum intermedium:
a- Lies between outer enamel epithelium & stellate reticulum.
b- Is a transient structure.
c- Is rich in mucopolysaccharides.
d- Plays important role in enamel calcification.

16- The down growth of an epithelial thickening buccal to the dental lamina is known as:
a- Vestibular lamina.
b- Linguo-alveolar Sulcus.
c- Lateral dental lamina.
d- Successional dental lamina. 

17- The dental lamina is induced to proliferate into a tooth bud by the:
a- Basement membrane.
b- Nerve endings.
c- Ecto-mesenchyme.
d- Oral epithelium.

18- Calcified tissues of the tooth are derived from:
a- Ectoderm only.
b- Endoderm only.
c- Mesoderm only.
          d- Ectoderm & Mesoderm.

19- A layer of cells that seems to be essential to enamel formation but does not actually secrete the enamel is:
a- Outer dental epithelium.
b- Stratum intermedium.
c- Reduced dental epithelium.
           d- Vestibular lamina.

20- The stimulus that initiates the actual formation of enamel matrix seems to be:
a- Reduction of stellate reticulum.
b- Influence of increased vascularization of the dental sac.
c- Disappearance of the cell free zone of dental papilla.
d- Presence of predentin.



21- The number of roots that are formed is determined by the:
a- Number of root sheaths developed by the enamel organ.
b- Number of medial ingrowths at the epithelial diaphragm.
c- Number of root sheaths developed by the dental sac.
d- Thickness of the cervical loop.

22- Which of the following is the first process to occur in the sequence of tooth development:
a- Deposition of the first layer of enamel.
b- Deposition of the first layer of dentin.
c- Elongation of the inner dental epithelial cells.
d- Differentiation of odontoblasts.

23-All of the following are involved in the formation of a tooth except:
a- Epithelial root sheath.
b- Successional lamina.
c- Dental lamina.
  d- Vestibular lamina.

24- The dental lamina initiating the permanent molars develops:
a- As successional lamina.
b- As a distal extension of the dental lamina.
c- As lateral dental lamina.
     d- As vestibular lamina.

25-The cell rests of Malassez are derivatives of:
a- Cervical ameloblasts.
b- Outer enamel epithelium.
c- Dental papilla.
  d- Root sheath.

26- Odontogenesis of the primary dentition begins between:
a- The sixth & seventh week.
b- The fifth & sixth week.
c- The seventh& eighth week.
d- The fourth & fifth week.

27- The embryo's stomodeum is lined by:
a- Ectoderm.
b- Endoderm.
c- Mesoderm.
d- Ectomesenchyme.




28-  By the 6th week of tooth development, the oral epithelium is:
a- 2-3 layers thickness.
b- 3-4 layers thickness.
c- 4-5 layers thickness.
d- 2-5 layers thickness.

29- The vestibular lamina gives rise to:
a- The alveolodental sulcus.
b- The alveolobuccal sulcus.
c- The alveololingual sulcus.
d- The alveologingival sulcus.

30- The ectomesenchymal cell condensation just beneath the enamel organ is called:
a- Dental sac.
b- Dental follicle.
c- pulp.
d- Dental papilla.

31- The cells of the tooth bud have:
a- High RNA content only.
b- Low glycogen content only.
c- Increased oxidative enzyme activity only.
d- All of the above.

32- Regulatory genes play a significant role in tooth development, they:
a- Control the tooth position.
b- Control the tooth number.
c- Determine the tooth shape.
d- a & b.

33- Initiation of dental lamina is induced by:
a- Neural crest cell.
b- Endoderm.
c- Ectoderm.
d- Mesoderm.

34- Primordium for the permanent dentition appears as an extension of dental lamina into the ectomesenchyme:
a- Lingual to the developing primary tooth germ.
b- Labial  to the developing primary tooth germ.
c- Mesial to the developing primary tooth germ.
d- Distal to the developing primary tooth germ.


35- The region where the inner and outer enamel epithelium meets at the rim of the enamel organ is known as:
a- Zone of Flection.
b- Cervical loop.
c- Epithelial Diaphragm.
d- Root Sheath of Hertwing's.

36- Which the followings is not a  function of stellate reticulum:
a- Protection of the underlying dental tissues.
b- Maintenance of tooth shape.
c- Support the production of enamel.
d- Control the position & number of tooth germs.

37- The epithelial pearls are derived from:
a- Dental lamina.
b- Dental pulp.
c- Dental sac.
d- Dental organ.

38- Odontoblasts start their secretory activity:
a- Before enamel matrix production.
b- After enamel matrix production.
c- During enamel matrix production.
d- During & after enamel matrix production.

39- Preameloblasts differentiate into ameloblasts:
a- After the differentiation of odontoblasts.
b- Before the differentiation of odontoblasts.
c- During the differentiation of odontoblasts.
d- During & after the differentiation of odontoblasts.

40- During the early stages of tooth development three transitory structures may be seen, these structures are:
a- Enamel knot, enamel organ & enamel niche.
b- Enamel knot, enamel cord & enamel niche.
c- Enamel knot, enamel organ & enamel epithelium.
d- Enamel niche, enamel organ & enamel knot.

41- The epithelial rests in the periodontal ligament are derived from:
a- Dental pulp.
b- Epithelial root sheath of Hertwing's.
c- Vestibular lamina.
d- Dental sac.




42- Appositional stage is confined to:
a- Cap stage.                                       b- Bud stage.
c- Bell stage.                                       d- Dental lamina.

43- Concresense usually occurs with:
a- Permanent maxillary molars.
b- Permanent maxillary premolars.
c- Permanent mandibular premolars.
d- Permanent mandibular premolars.

44- Supernumerary roots occur mainly with:
a- Permanent third molars.
b- Permanent second  molars.
c- Permanent first molars.
d- Permanent second premolars.

45- Enamel pearls occur in:
a- Apical third of molars roots.
b- Furcation area of molars.
c- Cervical third of molars roots.
d- Furcation area of premolars.

46- The process of differentiation of mesenchymal cells into
 Odontoblasts is called:
a- Initiation.                                       b- Induction.
c-Apposition.                                     d- Morphodifferentiation.

47- The epithelial root sheath of Hertwing's is composed of:
a-Outer enamel epithelium & inner enamel epithelium.
b- Inner enamel epithelium & stratum intermedium.
c- Outer enamel epithelium & stellate reticulum.
d- Stellate reticulum & stratum intermedium.

48- Inner dental epithelium:
a- Consists of a single layer of cuboidal epithelial cells.
b- Consists of a single layer of columnar epithelial cells.
c- Consists of a single layer of polyhedral epithelial cells.
d- Consists of a single layer of polygonal epithelial cells.

49- Determination of the initial position of the first cusp of the tooth during crown pattern formation may be achieved by:
a- The enamel knot.                              b- The enamel cord.
c- Both enamel knot and cord.                d- None of the above.



50- Before enamel formation begins:
a- Enamel knot disappears and enamel cord remains.
b- Enamel knot remains and enamel cord disappear.
c- Both knot and cord disappear.
d- Both knot and cord remain.

51- Concerning the stellate reticulum one of the following statements is wrong:
a- Occupies the central portion of the dental organ.
b- Lies between outer and inner dental epithelia.
c- Synthesizes and secretes glucoseaminoglycans.
d- Becomes polyhedral in shape.

52- The dental sac is:
a- The condensation of the ectomesenchymal cells surrounding the dental organ.
b- The condensation of the ectomesenchymal cells surrounding the dental
     papilla.
c- The condensation of the ectomesenchymal cells surrounding the dental organ
     and dental papilla.
d- None of the above.

53- The main difference between bell and apposition stage is:
a- The formation of first layer of E.
b- The formation of first layer of D.
c- The formation of first layer of C.
d- The formation of first layer alveolar bone.

54- Concerning the stratum intermedium, one of the following statements is incorrect:
a- It is composed of 2-3 layers of squamous epithelial cells.
b- It is differentiated between the inner enamel epithelium and stellate reticulum.
c- It is connected to each other and to the cells of stratum intermedium by
    desmosomes.
d- It is essential for enamel formation as it contains acid phosphatase enzyme.

55- Which one of the following functions of the inner dental epithelium is wrong?
a- It exerts an organizing influence on the undifferentiated cells of the dental
 papilla to differentiate into ameloblasts.
b- It shares in the transport of the nutritive materials.
c- It determines the future incisal or occlusal crown pattern.
d- It lays down enamel matrix and helps in its mineralization.






56- The epithelial root sheath of Hertwig can't be seen as a continuous layer in the developing root because:
a- The rapid epithelial sheath proliferation.
b- The dentin formation.
c- The rapid epithelial sheath destruction after dentin formation.
d- All of the above.

57- Epithelial rests of Malassez are:
a- Epithelial strands and may undergo degeneration only.
b- Epithelial remnants of the epithelial root sheath of Hertwig only.
c- Network or isolated islands in the P.L. only,
d- All of the above.

58- If Hertwig's epithelial root sheath does not disintegrate:
a- No cementum will be formed on the radicular dentin.
b- It is likely that some of the enamel will be resorbed.
c- The apical end of the junctional epithelium will lie occlusal to the
 cemento-enamel junction.
d- Predentine will form on the outer surface of the radicular dentin.

59-The reduced enamel epithelium is derived from:
a- Maturative ameloblasts and stratum intermedium.
b- Stratum intermedium, stellate reticulum and outer dental epithelium.
c- Stratum intermedium, stellate reticulum and inner epithelium.
d- Protective ameloblasts, stratum intermedium, stellate reticulum and      outer dental epithelium.

60-Which of the following is not component of the enamel organ?
a- Ameloblasts.
b- Odontoblasts.
c- Outer enamel epithelium.
     d- Stratum intermedium.

61- Which of the following indicates the major components of a tooth germ?
a- The dental lamina, the stellate reticulum and the stratum intermedium.
b- The dental organ, the dental papilla and the dental sac.
c- The dental pulp, the dental sac and the dental lamina.
d- The cervical loop, Hertwig's sheath and the inner enamel epithelium.

62- Which of the following is not ectodermal in origin?
a-    Epithelial rests of Malassez.
b-   Anterior pituitary gland.
c-    Stellate reticulum.
      d- Enamel spindles.


63- Which of the following appear FIRST in a developing tooth?
a-    Predentin.
b-   Cementoid.
c-    Tome's process.
d-   Secondary dentin.

64- The last hard dental tissue to be deposited is:
a-     Enamel.
b-    Outer layers of cementum.
c-     Mantle dentin.
     d- Primary dentin.

65- Which of the following is associated with an erupted tooth?
a-     Outer Enamel epithelium.
b-    Cervical loop.
c-     Epithelial rests of Malassez.
     d- Stratum intermedium.

66- Which of the following is not true of Hertwig's epithelial root sheath?
a-            It lacks a stellate reticulum.
b-            It is derived from stomodeal ectoderm.
c-             Its remnants form epithelial rests.
d-            It remains intact until a layer of cementum has been formed.

67- Which of the following contain blood vessels?
a-            Cartilage.
b-            Enamel.
c-             Dental lamina.
d-            Dental sac.

68- Which group of structures is entirely derived from the dental sac?
a-            Dentin, pulp, cementum.
b-            Cementum, alveolar bone, pulp.
c-             Cementum, enamel, pulp.
d-             Periodontal ligament, cementum, alveolar bone.

69-The development of the root begins when
         a) The inner and outer dental epithelium reaching the future C.E.J.
         b) The crown is completely formed.
         c) The development of the supporting bone begins.
         d) The development of the periodontal ligament begins.





70- The function of the inner dental epithelium is……..
         a) Exerts organization influence on the dental papilla cells.
         b) Lays down dentin matrix             
 c) Protects the enamel after eruption.
         d) Provides the enamel organs with alkaline phosphatase

71-The tooth germ is composed of
        a) Dental papilla, dental follicle, dental organ.
        b) Dental follicle, dental lamina, vestibular lamina.
        c) Dental papilla, dental lamina, dental organ.
        d) Dental organ, dental follicle, dental lamina.

72-The apposition stage of tooth development begins
a) When the root of the tooth begins to develop.
b) When the first layer of dentine is deposited.
c) When odontoblast start to differentiate.
d) When the first layer of enamel lay down.

73- What statement about epithelial diaphragm is Not true?
a- It produces narrowing of the wide cervical opening.
b- Its proliferation is accompanied by proliferation of pulp cells
     adjacent to diaphragm.
c- It's growing end  is located coronal to the root sheath.
d- It grows in a horizontal plane.

74- The cells of the stratum intermedium:
a- Have a stellate outline.
b- Are not yet differentiated in the bell stage.
c- Are in direct contact with the outer dental epithelium.
d- Are characterized by high alkaline phosphatase enzyme activity.

75-The dental follicle:
a- Is an epithelial structure.
b- Give rise to the radicular pulp.
c- Is not present in permanent teeth.
d- give rise to cementum.

76-If the process of morphogenesis is disturbed:
a- Changes will occur in the shape of crown and root.
b- Enamel formation will be abnormal.
c- Dentin formation will be abnormal.
d- Absence of cementum.




77- The mesenchymal cells lying adjacent to the inner enamel epithelium:
a- Differentiate into ameloblasts.
b- Differentiate into odontoblasts.
c- Are under the influence of stellate reticulum.
d- Become markedly folded.

78- The dental lamina:
a- Breaks at the cap stage.
b- Has no branching.
c- Has no remnants.   
          d- Develops from the oral epithelium.

79- Advanced bell stage of tooth development refers to:
a- Histodifferentiation , morphodifferentiation.
b- Initiation & Proliferation.
c- Mesenchymal condensation.
d- Apposition of dental tissues.

80- The epithelial component of the tooth germ is known as:
a- Dental lamina.
b- Dental papilla.
c- Enamel organ.
d- Dental follicle.

81- Which of the following is not part of the tooth germ?
a- Dental papilla.
b- Dental follicle.
c- Dental lamina.
d- Enamel organ.

82- The dental sac plays an important role in the formation of all of the following except:
a- Periodontal ligament.
b- Dentin of the root.
c- Alveolar bone proper.
          d- Cementum.

83- After the crown of the tooth is formed, the dental papilla is called:
a- Dental pulp.
b- Pulp stone.
c- Dental sac.
d- Dentin.




84- In a developing tooth, if Hertwig's sheath and the epithelial diaphragm were failed to form, the resulting tooth would exhibit:
a-            No radicular dentin.
b-            Malformed or fused roots.
c-             Acellular, but no cellular, cementum.
d-            Defective enamel in the cervical region.

85- The reduced enamel epithelium:
a-            Lacks cells derived from the stellate reticulum.
b-            Contains protective ameloblasts.
c-             Overlies immature enamel which has not yet reached its full thickness.
d-            Does not cover enamel located at the cervical end of the crown.

86- Which of the following is a component of tooth germ?
a- Lateral dental lamina.
b- Successional lamina.
c- Vestibular lamina.
d- Dental sac.

87- The origin of enamel is:
a- Endoderm.
b- Mesoderm.
c- Ectoderm.
d- Ectomesenchyme.

88-Which statement about early dental development is incorrect?
a-     Cap stage is accomplished by unequal growth in different parts.
b-    In the cap stage the inner and outer enamel epithelial cells are completely alike.
c-     The transition from cap stage to bell stage is particularly marked by the full differentiation of stellate reticulum.
d-    The dental papilla and the dental sac develop in the cap stage.

89- The dental sac gives rise to:
a- Cementoblasts and periodontal ligament.
b- Periodontal ligament and dental pulp.
c- Dental pulp and attachment epithelium.
d- Odontoblasts and Cementoblasts.








Answers of MCQ

Tooth development


1
c
31
d
61
b
2
d
32
d
62
d
3
c
33
d
63
a
4
a
34
a
64
b
5
d
35
a
65
c
6
c
36
d
66
d
7
d
37
a
67
d
8
c
38
a
68
d
9
d
39
a
69
b
10
d
40
b
70
a
11
d
41
b
71
a
12
b
42
c
72
b
13
d
43
a
73
c
14
a
44
a
74
d
15
d
45
b
75
d
16
a
46
a
76
a
17
c
47
a
77
b
18
d
48
b
78
d
19
b
49
a
79
d
20
d
50
c
80
c
21
b
51
d
81
c
22
c
52
c
82
b
23
d
53
b
83
a
24
a
54
d
84
a
25
d
55
a
85
b
26
a
56
c
86
d
27
a
57
d
87
c
28
a
58
a
88
b
29
b
59
d
89
a
30
d
60
b


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Embryology

 

1-Which of the following is not a correct pairing of embryonic structure and adult derivative?

a-            Maxillary processes: secondary palate.
b-           Primary palate: upper incisor teeth.
c-            Second pharyngeal arch: mandible.
d-           Lateral lingual swellings: anterior 2/3 of tongue.

2-Which of the following are all derived from the stomodeal ectoderm?
a- Salivary glands, anterior pituitary gland and enamel organs.
b- Enamel dentin and major salivary glands.
c-  Cementum, anterior pituitary gland and stratum intermedium.
d- Dental lamina, dental papilla and dental sac.

3- Which of the following does contribute to the formation of the upper lip?
a- Lateral nasal process.
b-Two maxillary processes & medial nasal process.
c- Medial nasal process.
       d- First branchial arch.

4- The palatal shelves (palatine processes):
a-  Are covered by endoderm.
b- Are derived from the primary palate.
c-  Must assume a vertical position for palate closure to occur.
         d- Are derived from the first branchial arch.

5- An oblique facial cleft is formed:
a-    Due to the rupture of the buccopharyngeal membrane.
b-   When the maxillary process fails to fuse with the mandibular processes.
c-    When the maxillary process fails to fuse with the lateral & medial
            nasal  process.
d-   When the medial nasal process fails to fuse with the maxillary process.

6- The extrinsic muscles of the tongue:
a-    Develop from the maxillary process.
b-   Develop from occipital myotomes.
c-    Develop from tuberculum impar.
      d- Develop from the second branchial arch.




7- Which of the following embryonic structures contribute to the formation of     lower lip:
a-     Maxillary process.
b-    Maxillary & medial nasal processes.
c-     Medial & lateral nasal processes.
     d- Two mandibular processes.

8- The tongue is not derived from:
a-            Two lingual swellings.
b-            Second branchial arch.
c-             Third branchial arch.
  d-     Copula of His.

9- Palatine processes are derived from:
a-     Maxillary processes.
b-            Mandibular processes.
c-      Copula of His.
  d-     Medial nasal process.

10- The maxillary processes:
a-            Are covered with endoderm.
b-            Are derived from the 1st branchial arch.
c-             Form the primary palate.
d-           Form the entire upper lip.

11- A unilateral cleft lip is formed when:
a-            The palatal shelves remain in a vertical position.
b-            The bucco-nasal membrane ruptures.
c-             One maxillary process fails to fuse with the medial nasal process.
  d-     One lateral nasal process fails to fuse with the maxillary process.

12- The soft palate develops from:
a-            Primary palate.
b-            Palatal processes fused with the nasal septum.
c-             Medial nasal process.
d-            Palatal processes which are not fused with nasal septum.

13-Branchial archs sharing in tongue development are:
        a) First & second.
        b) First.
        c) Second & third.
        d) First, third & fourth.




14- The Stomodeum is lined by
a) Endoderm.                            
b) Mesoderm.
c) Ectoderm.
d) Endoderm & Mesoderm

15- The palatal shelves:
a-     Develop from the lateral nasal processes.
b-            From the primary palate.
c-      Develop from the medial nasal processes.
  d-     Develop from the maxillary processes.

16- The ossification center of the developing mandible arise between:
a- inferior dental and lingual nerves.
b- mental and incisive nerves
c- mandibular and maxillary nerves.
d- superior alveolar and infra-orbital nerves.

17-The extrinsic muscles of the tongue are supplied by:
a-trigeminal nerve.
b-hypoglossal nerve.
c-facial nerve.
d- lingual nerve.

18- Secondary palate is developed from the :
a- 1st branchial arch .                                           b-2nd branchial arch.
c- 3rd branchial arch.                                           d- fronto-nasal process.

19-The muscles of mastication are derived from:
a- occipital myotomes.                                        b- 3rd branchial arch.
c- 1st branchial arch.                                            d- 2nd branchial arch.

20- palatine processes are derived from:
a- fronto- nasal process.                                     b-lateral nasal process.
c- 3rd branchial arch.                                           d- maxillary processes.

21- Tongue begins to develop at:
a-6th w.i.u.                   b- 11th w.i.u.                  c-4th w.i.u.       d- 8th w.i.u.

22- Ossification center of maxilla arises between:
a-maxillary and mandibular nerves.
b-anterior superior alveolar nerve and infraorbital nerve.
c- posterior and middle superior alveolar nerves.
d- inferior alveolar and lingual nerves.

23- First branchial arch is supplied by:
a- facial nerve.
b- glossopharyngeal nerve.
c- hypoglossal nerve.
d- mandibular nerve.

24-The neural crest cells give rise to:
a- Bone, dentine and cartilage.
b-Enamel, dentine and bone.
c- Sensory cells, enamel and dentine.
d- Fibroblasts, pericytes and enamel.

25- Which of the following are derived from Meckel's cartilage:
a- Mental ossicles, incus and malleous of the middle ear.
b- Lingula of the mandible and middle ear.
c- stylo-mandibular ligament.
d- All of the above.

26-The inferior parathyroid gland originates from :
         a- First pharyngeal pouch.
         b-First pharyngeal cleft.
         c- Third pharyngeal pouch.
         d- Fourth pharyngeal pouch.

27- The development of secondary palate begins from:
         a-  3-4 W.I.U.
         b-  4 -5 W.I.U.
         c-  15-16 W.I.U.
         d-  6-9 W.I.U.

28- The occipital somites myotomes give rise to
         a- Muscles of mastication          b- Muscles of the lip.
         c- Muscles of the tongue.
         d- Muscles of cheek.

29- The malleus of inner ear originates from:
         a- Condylar cartilage.          b- Coronoid cartilage.
           c- Meckel’s cartilage.        d-None of the above.








Answers of MCQ

EMBERYOLOGY

1
c
15
d
2
a
16
b
3
b
17
b
4
d
18
a
5
c
19
c
6
b
20
d
7
d
21
c
8
b
22
b
9
a
23
d
10
b
24
a
11
c
25
a
12
d
26
c
13
d
27
d
14
c
28
c


29
c






















Eruption

1- Which of the following pairs of movements predominate during the post-eruptive period?
a-     Distal and lingual.
b-    Axial and mesial.
c-     Distal and axial.
d-    Axial and rotational.

2- Passive eruption is:
a-     Growth in the length of the root.
b-    Apical migration of the junctional epithelium.
c-     Deposition of bone at the fundus.
d-    The formation of cellular cementum.

3- Which of the following does not occur during the eruptive phase?
a-     Dentin deposition.
b-    Narrowing of apical foramen.
c-     Increased thickness of cementum.
    d- Enamel formation.

4- During the pre-eruptive phase of tooth eruption:
a-            Cementoblasts begin to secrete cementoid.
b-            The apical foramen is beginning to close.
c-             The developed tooth at the bell stage lies within a crypt of bone.
d-            The root is formed.

  5- Which of the following occurs during the pre-eruptive stage of eruption of
          a   tooth:
a- Differentiation of the stratum intermedium.
b- Formation of the dental sac.
c- Formation of stellate reticulum.
d- Maturation of enamel.

  6- Active eruption of the tooth:
a- Begins as soon as the roots have begun to develop.
b- Begins when the apical cementum is deposited on the roots of the tooth.
c- Begins as the occlusal tip starts moving towards the occlusal plane.
d- Continues until exposure of the cementum has occurred.

 




7- The root formation theory of eruption proposes, that eruption is due to
       the push of the:
a- Expanding pulp in the root canals against the alveolar crypt.
b- Elongating roots against the base of the alveolar crypt.
c- Elongating roots against the Hammock ligament.
d- Proliferating periodontal ligament.

8-Actual eruptive movements of tooth occur mainly in a :
     a) Horizontal direction.
       b)Complex pattern.
c) Axial direction.
d) Rotational direction.

9-Which of the following does not occur in the active phase of tooth eruption:
     a-Organization of a periodontal ligament from the dental follicle.
b- Gradual separation of attachment epithelium from the enamel surface.
c- Root formation.
d- Occlusal wear.

 10-The most likely factor responsible for tooth eruption is:
a- Vascular pressure.
b- The developing periodontal ligament.
c- Bone growth.
d- The growing root.

 11-All of the following statements about the eruption of a permanent tooth and the exfoliation of its predecessor are true, except:
a- Prior to eruption, the permanent tooth is completely formed.
b- Resorption of deciduous roots is an intermittent process.
c- Earliest resorption of deciduous roots is on root surface, facing the permanent tooth.
d- Eruptive movements of the permanent tooth may not be solely responsible for deciduous root resorption.

12-When a tooth first erupts into the oral cavity, the attachment epithelial cuff      is composed of epithelium derived from:
a- Dental lamina.
b- Epithelial rests of Malassez.
c- Reduced dental epithelium.
d- Epithelial root sheath of Hertwig's.

     13- In the posteruptive phase a tooth undergoes primarily:
a- Rotational movement.
b- Movements in a distal direction.
c- Movements in an apical direction.
d- Movements in an axial & mesial direction.

   14- During tooth eruption, the permanent successors of the primary teeth move occlusaly and:
a- Mesially.
b- Buccally.
c- Lingually.
d- Distally.

  15- During tooth eruption into the oral cavity, what happens to the epithelial covering of the enamel:
a- It remains as the primary cuticle.
b- It units with the oral epithelium and then degenerates.
c- It is replaced by oral epithelium and then degenerates.
d- It units with the oral epithelium and becomes primary cuticle.

  16- During tooth eruption, bone formation is often seen at the base of socket. This newly formed bone is usually in the form of:
a- Coarse fibered woven bone.
b- Compact bone.
c- Radiating bone.
d- Horizontal trabeculae.

17-The pre-eruptive phase:
      a- Begins in the late bell stage.
      b- Begins in the early bell stage.
      c- Begins in the beginning of root formation.
      d- Begins in the cap stage.

18- Types of movement during the pre-eruptive phase:
      a- Axial- eccentric.
      b- Eccentric-tilting.
      c- Bodily-eccentric.
      d- Bodily- axial.

19- Eruptive phase:
      a- Accompanied by bleeding of the gingival.
      b- No discomfort or pain.
      c- Eruptive teeth move at different speeds, at different times.
      d- Has only axial occlusal movement.

20-Histological changes occurring during the eruptive phase:
      a- Root formation only.
      b- Formation of the attachment apparatus only.
      c- Dento- gingival junction appearance only.
      d- All of the above.

Answers of MCQ

ERUPTION

1
b
11
a
2
b
12
c
3
d
13
d
4
c
14
b
5
d
15
b
6
a
16
d
7
d
17
b
8
c
18
c
9
d
19
c
10
b
20
c































Shedding

1- During shedding which of the following is wrong:
a- The pulp plays an active role.
b- The pulp plays a passive role.
c- The pulp appears histologically normal till the end of the process.
d- The neural elements remain in the pulp until shedding is completed.

2- Which of the following is true about ankylosis?
a- Is a union of the tooth with the periodontal ligament.
b- The active eruption of an ankylosed tooth continues.
c- Is a bony union between the alveolar bone and the roots of teeth.
d- Ankylosed teeth do not show Howship's lacunae on the root.

3- Shedding is predominantly the:
a- Physiologic loss of impacted teeth.
b- Pathologic loss of non-vital primary teeth.
c- Physiologic loss of permanent teeth.
d- Physiologic loss of primary teeth.



















Answers of MCQ

Shedding

1
b
2
c
3
d























Enamel

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

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

3-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.

4- 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.

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

6- 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.

7- 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.


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

9- 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.

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

11- 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.

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

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

14- 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.




15- 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.

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

17-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.

18- 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.

19- 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.

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




22- 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- 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- 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.

26- Hypocalcified areas in enamel are:
a- Enamel spindles.
b- Dentino-enamel junction.
c- Interprismatic substances.
d- Enamel tufts.

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.

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.




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.
                                                                                            
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.

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.

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.

33- The predominant inorganic portion of enamel is:
a- Calcium.
b- Carbonate.
c- Phosphate.
d- Fluoride.

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

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




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. 

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.

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.
            
39- 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.

40- 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.

41- Enamel spindles are formed by:
a- Odontoblastic process.
b- Ameloblastic process.
c- Hypocalcified rods.
d- Cracks.

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.

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.

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.

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.

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.

47- Unmineralized structures seen in the enamel are :
a- Cross striations.
b- Enamel tufts.
c- Incremental lines of Retzius.
d- Enamel spindles.

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.

49-Incremental lines of Retzius appear:
a- In dentin.
b- In enamel.
c- In cementum.
d- In bone.


50-Primary enamel cuticle is:
a- Afibrillar cementum.
b- Precipitate of salivary proteins.
c- Relatively structureless layer of enamel.
d- A last product of ameloblasts.

51- Hunter-Schreger bands have all the following characteristics except:
a- They are best seen in reflected light.
b- They are alternating dark and light bands
c- They are most likely an optical phenomenon
          d- They are found at the cusp tip.

52- Enamel tufts and enamel lamellae resemble each other in that both:
a- Are formed prior to tooth eruption only.
b- Extend over full thickness of the enamel.
c- Are hypermineralized structures.
d- Are hypomineralized structures.

53-Enamel is by weight:
a- 70% mineral, 26% organic matrix, 4% water.
b- 76% mineral, 20% organic matrix, 4% water.
c- 25% mineral, 12% organic matrix, 3% water.
  d- 95% mineral, 1% organic matrix, 4% water.

54- 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.

55- Enamel is:
          a. An ectodermal tissue covering the anatomical crown.
          b. A mesodermal tissue covering the crown.
          c. An endodermal tissue.
          d. A mesenchymal tissue.

56- Gnarled enamel has the following criteria except:
          a. Found under cusp tips and incisal ridges.
          b. The course of the enamel rods is more straighter.
          c. The enamel rods become twisted and braided.
          d. Found to give maximum strength to the areas subjected more to the masticatory forces.

57- The peripheral part of the E rod is called:
          a. Interrod region.                    b. Rod sheath.
          c. Rod region.                          d. Key hole.

58- 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.

59- The interrod enamel is:
          a. More calcified than the E. rod.
          b. Less calcified than the E. rod.
          c. The same calcification as the E. rod.
          d. Organic in nature.

60- Cross striations or short increments:
          a. Represent the rhythmic apposition of the E. matrix by ameloblasts.
          b. Represent alternating constriction and expansion of E. rods at and in-between
               the striations.
          c. Represent the daily rate of secretory activity of the ameloblast.
          d. All of the above.                 

61- The formation of the enamel matrix between two short increments needs:
          a. One day.                       b. Two days.
          c. Three drays.              d-Four days.

62- Neonatal line is all the following except :
          a. Is one of the brown striae of Retzius that gets accentuated.
          b. Is present in deciduous teeth and all permanent molars.
          c. Separates enamel formed before birth from that formed after birth.
          d. It is due to abrupt change in nutrition and environmental condition at birth.

63- The quality of the prenatal Enamel:
          a. Is better than that of the postnatal E.
          b. Is not as better as that of the postnatal E.
          c. Is equal to the quality of postnatal E.
          d. Not related to the quality of postnatal E.

64- The dentinoenamel junction (DEJ)  :
          a. Appears to be scalloped with convexities of the scallops directed to E.
          b. Appears to be scalloped with convexities of the scallops directed to D.
          c. Appears to be scalloped with convexities of the scallops directed to
              cementum.
          d. Non of the above.




65- The firm attachment between E and D is due to:
          a. Under cuts created by the scallops of the DEJ.
          b. Interdigitation at the DEJ between fibrils of first formed layer of D and that of
              first formed layer of E.
          c. Interdigitation between the hydroxyapatite crystals that are deposited during
              mineralization of E and D.
          d. All of the above.                 

66- E. lamellae are all the following except :
          a. Thin leaf or sheet like structures.
          b. Extend from the E surface and may extend to D.
          c. Demonstrated in the longitudinal ground section only.
          d. Hypo or unmineralized structures

67- Enamel spindles:
          a. They are odontoblastic cell bodies pass across the DEJ into the E.
          b. They are extended between the preameloblasts after enamel is formed.
        c. They are most common beneath cusps.
          d. They are best demonstrated in longitudinal decalcified section.

68- Rodless Enamel:
          a. Occurs in the outermost 70 microns of the E.
          b. Their crystals are aligned at right angel to the surface
          c. Found most common  at the cervical areas of E surface.
          d. All of the above.

69- Perikymata are:
          a. Vertically oriented wave like grooves.
          b. The external manifestation of the brown striae of Retzius.
          c. Numerous at the incisal or cusp regions.
          d. Parallel to the AEJ

70- Which of the following tissues begins formation first:
          a. Enamel.                                    b. Dentin.
          c. Pulp.                                           d. Cementum.

71- Attrition is characterized by:
          a. Being a condition of normal wear of the occlusal      and proximal surfaces.
          b. A chemical loss of occlusal tooth structure, but not from dental caries.
          c. A loss of crown structure on the occlusal surface by mechanical means.
          d. None of the above.

72- In mature dental tissues, the only tissue whose cells are lost is:
       a. Dentin.                                                       b. Enamel.
       c. Cementum.                                                           d. Pulp.

73- Incremental lines of Retzius appear:
          a. In dentin and follow the appositional pattern.
          b. In enamel and follow the appositional pattern.
          c. In cementum and follow the appositional pattern.
d. As lines in E running at right angles to the E surface.

74- Enamel is by weight:
          a. 88-90 % mineral, 10-12 % organic matrix and water.
          b. 76% mineral, 20% organic matrix, 4 water.
          c. 25% mineral, 12% organic matrix, 3% water.
          d. 96% mineral, 1-2% organic material, 2-3% water.

75- Which of the following is not true about Enamel rod ?
          a. They run from the dentinoenamel junction to the crown surface.
          b. Length of all enamel rods is equal.
          c. They are the basic structural units of E.
          d. They may be hexagonal ,rounded, oval or keyhole shape in cross section .

76- Which of the following statements about E . is false?
          a. The heads of enamel rods are directed cervically, the tails occlusally.
          b. Rod sheaths are relatively hypocalcified areas surrounding the rods.
          c. Human E rods in cross section have an outline similar to a keyhole.
          d. Hydroxyapatite crystals run parallel to the long axis of the rods and perpendicular to it in the interrod region .

77- It is particularly difficult to finish the wall of a cavity preparation in cuspal enamel because of the presence in that area of:
          a. Tufts.                                 b. Horizontal E. rods.
          c. Gnarled E.                       d. Spindles.

78- Enamel tufts and Enamel lamella resemble each other, in that both:
          a. Are formed after to tooth eruption.
          b. Extend over full thickness of the enamel.
          c. Are hypermineralized structures.
          d. Are oriented in a vertical direction perpendicular on the DEJ.

79- All of the following statements about the incremental lines of Retzius in Enamel are true except:
          a. In longitudinal section they run obliquely, relative to D.E.J.
          b. Perikymata in newly erupted teeth are manifestations of the lines of Retzius.
          c. They are formed as a result of rhythmic variations in the calcification.
          d. Under no conditions can a line of Retzius to be a neonatal line.




80- E. has no possibility of self repair because:
          a. It has a small percentage of organic content.
          b. Its formative cells are lost once it is fully formed and the tooth erupted.
          c. It is essentially a keratin tissue and has no blood vessels.
          d. It has no direct connection with the active cells of the pulp tissue.

81- At the time Enamel matrix is first formed in a tooth:
          a. No predentin has yet been formed.
          b. Root of the tooth is largely covered with acellular cementum.
          c. Nuclei of ameloblasts move to non secreting end of the cell.
          d. Cells of stellate reticulum near the cervical portion of the tooth have lost their
               nuclei.

82- Hypomineralized structures which extend from the D.E.J to the surface of the Enamel are called:
          a. Hunter schreger bands.
          b. E. spindle.                          
           c. Incremental lines of Retzius.
          d. Enamel lamellae.

83- Maturation of Enamel is characterized by a percentage increase in inorganic content and a percentage:
          a. Increase in water.
b. Decrease in water and organic content.
c. Increase in water and decrease in organic content.
d. Decrease in water and increase in organic content.

84- The stimulus that initiates the actual formation of Enamel matrix seems to be the:
          a. Presence of predentin.
          b. Reduction of stellate reticulum.
          c. Influence of increased vascularization of the dental sac.
          d. Reversal of functional polarity of ameloblast.

85- In a routine demineralized histological section of an adult tooth, the area representing Enamel is generally optically clear because:
          a. The mounting medium has the same refractive index as enamel.
          b. E is very brittle and thus breaks off during sectioning.
          c. Ordinary stains don't stain the organic matrix of E.
          d. Enamel is highly calcified.






86- A layer of cells that seems to be essential to enamel formation but does not actually secrete the enamel is:
          a. Inner dental epithelium.
          b. Stratum intermedium.
          c. Reduced dental epithelium.
          d. Vestibular lamina.

87- Which of the following are poorly calcified Enamel:
          a. Gnarled E .and  E rods.
          b. E. lamellae and incremental lines.
          c. Perikymata and gnarled E.
          d. E. rods and incremental lines.

88- Enamel matrix is laid down by ameloblasts:
          a. Finally contains about 80% by weight inorganic matter.
          b. Includes organic matter that is primarily collagen.
          c. Persists as a vital tissue through the life of a tooth.
          d. Non of the above.

89- Enamel tufts:
          a. Begin on the outer edge of E .
          b. Are developmental defects and are worn away by masticatory forces.
          c. Have a brush like appearance and are  hypo calcified areas in E.
          d. Represent hypercalcified E. rods.

90- The rod sheath:
          a. Has cross striations.
          b. Is more calcified than the E. rod.
          c. Is less calcified than the E. rod.
          d. Has lesser amount of organic matter than the E. rod.

91- Ionic exchanges between erupted Enamel .and Saliva:
          a. Don't occur as the formative cells of the E .are lost once it is formed.
          b. Occur only for two to five years following eruption.
          c. Cease at puberty.
          d. Occur throughout life.

92- The predominant organic portion of mature  Enamel. is:
          a. Calcium.                              b. Fluoride.
          c.Enamelin.                              d. Phosphate.
           
93- Fluorine deposition in Enamel:
          a. Increase with age.
          b. Decrease with age.
          c. Sometimes increases or decreases with age.
          d. Not affected by age.

94- Which of the following organic components are present in Enamel:
          a. Carbohydrates.                    b. Fat.
          c. Proteins.                              d. All of the above.
         
95- The rodless layer of enamel:
a-    Is found only in primary teeth.
b-   Does not contain rod and rod sheaths.
c-    Is found near the amelo-dentinal junction.
d-   Contains no hydroxyapatite.

96- Hunter-Schreger bands are:
a-found in the outer surface of enamel.
b-run parallel to the striae of Retzius.
c-best visualized in transverse section of the crown.
d-reflect periodic changes in prism direction of enamel.

97- The direction of enamel rods in general is:
a-parallel to the outer surface of enamel.
b-parallel to dentine.
c-perpindicular to the amelo-dentinal junction.
d-random.

98- Which of the following contains the highest concentration of hydroxyapatite:
a-cementum.
b-enamel.
c-primary dentine.
d-secondary dentine.

99- Enamel prism of the cusp tip passes:
a- in wavy course.
b- in s-shape course.
c- in straight course.
d- in twisted course.

100-Developmental enamel lamellae is:
a- type A enamel lamellae.
b- type B enamel lamellae.
c- type C enamel lamellae.
d- accidental enamel crack.

101- The structures which are not seen in a decalcified section are:
a-                 Dentinal tubules.
b-                Incremental lines of Retzius.
c-                 Secondary dentin.
d-                Cellular cementum.
Answers of MCQ

Enamel

1
b
31
d
2
a
32
c
3
d
33
a
4
c
34
a
5
d
35
b
6
b
36
a
7
b
37
c
8
d
38
b
9
d
39
d
10
b
40
c
11
b
41
a
12
c
42
c
13
b
43
d
14
b
44
d
15
d
45
c
16
a
46
b
17
b
47
d
18
c
48
d
19
a
59
b
20
b
50
d
21
c
51
d
22
d
52
d
23
b
53
d
24
b
54
a
25
b
55
a
26
d
56
b
27
c
57
b
28
c
58
c
29
b
59
c
30
d
60
d

61
a
91
d
62
b
92
c
63
a
93
a
64
b
94
d
65
d
95
b
66
c
96
d
67
c
97
c
68
d
98
b
69
b
99
d
70
b
100
a
71
a
101
b
72
b


73
b


74
d


75
b


76
a


77
c


78
d


79
d


80
b


81
c


82
c


83
b


84
a


85
d


86
b


87
b


88
d


89
c


90
c

                                          

Click here for MCQs in Oral Histology Part- 2

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