|
|
Question
|
Answer
|
|
1
|
The bulk of the tooth is formed by the:
|
Dentin
|
|
2
|
The cell bodies of odontoblast are arranged along
the: |
Pulpal surface of dentin;
Explanation: Though the odontoblasts are the dentin
producing cells, like other mineralized cells, they do not lie in the tissue they form but lie in dentin. |
|
3
|
Physically and chemically the dentin resembles the:
|
Bone
|
|
4
|
The main morphologic difference between bone and
dentin is that bone has osteocytes while dentin has: |
Odontobalstic process;
Dentin contains only the processes of the cells
that was responsible for its formation where as bone contains the cell body itself within the matrix itself as the osteocyte. |
|
5
|
The color of dentin gradually with age becomes:
|
Darker.
With age dentin accumulates numerous fibers and
other materials that render the dentin darker. |
|
6
|
The organic content of dentin is:
|
35%
|
|
7
|
The unit cell of hydroxyl apatite has a formula of:
|
3 Ca 3 (PO4)2.
Ca (OH)2 |
|
8
|
The calcium hydroxyapatite has a formula of
|
Ca 10 (PO4)6 (OH) 2
|
|
9
|
The hydroxyapatite crystals in dentin have a shape
of: |
Plate;
Fish scale appearance is in light microscopic
appearance of enamel rods in cross section. Stubby rhombic crystals are the shape of biological hydroxyapatite crystals. |
|
10
|
The dentinal matrix of collagen fibers is arranged
in a: |
Random network
|
|
11
|
Each odontoblast gives rise to:
|
One process
|
|
12
|
The dentinal tubule has a:
|
Doubly curved course
|
|
13
|
The dentinal tubules have a straight course at:
|
Root apex area; Cervical area of crown; Incisal
edges/ cuspal tips |
|
14
|
From the pulp, the first convexity of dentinal
tubules is directed towards the: |
Apex of the tooth
|
|
15
|
Each of the dentinal tubule is oriented to the
pulpal surface at: |
Right angle
|
|
16
|
The dentinal tubule ends at the enamel/cementum at:
|
Right angle
|
|
17
|
The ratio between outer and inner surface of dentin
is about: |
Five: one.
Hence nearer to the pulp, dentinal tubules are
closely packed and outer most area of dentin it is spaced apart. |
|
18
|
The diameter of dentinal tubules at the pulpal
cavity is about: |
3 to 4 micrometers
|
|
19
|
The diameter of dentinal tubules at the enamel/
cementum end is about: |
1micrometer
|
|
20
|
1 mm2 of cavity prepared approximately exposes
|
30,000 dentinal tubules
|
|
21
|
The ratio of the number of tubules per unit area on
the pulpal to outer surface of dentin is about: |
Four: one.
Notes: Nearer to the pulp, dentinal tubules are
closely packed and outer most area of dentin it is spaced apart. Moreover the surface area at the inner surface is lesser than the outer surface area of dentin. |
|
22
|
At the pulpal surface, the dentinal tubules per mm2
area are: |
50,000 to 90,000 tubules
|
|
23
|
The dentinal tubules per mm2 area are highest in:
|
Crown
|
|
24
|
The dentinal tubules are very closely packed
towards: |
Pulpal surface
|
|
25
|
The lateral branches of dentinal tubules are
referred to as: |
Canaliculi
|
|
26
|
The diameter of canaliculi of dentin at the enamel/
cementum end is about: |
Less than 1micrometer
|
|
27
|
To the main dentinal tubules, the canaliculi
originate at: |
Right angle
|
|
28
|
The dentin that immediately surrounds the dentinal
tubule is the: |
Peritubular dentin
|
|
29
|
The highly mineralized dentin is
|
Periubular dentin
|
|
30
|
The type of dentin that has poor collagen content
& is highly mineralized is |
Peritubular dentin
|
|
31
|
The ratio of thickness of peritubular dentin between
outer and inner surface of dentin is: |
Two : one.
Notes: The thickness of peritubular dentin in
dentinoenamel junction is 0.75 micrometers while at the outer surface it is 0.40 micrometers. This peritubular dentin causes the constriction of dentinal tubules to about a micrometer in the dentinoenamel junction. |
|
32
|
The dentinal tubule wall has an organic lining
called as: |
Lamina limitans.
It is a thin organic membrane that has high content
of glycosaminoglycans. |
|
33
|
The main body of dentin is made of:
|
Intertubular dentin
|
|
34
|
Intertubular dentin is observed between:
|
Zones of peritubular dentin
|
|
35
|
After demineralization using acid, the mineralized
structure that does not retain the matrix is the: |
Peritubular dentin
|
|
36
|
The width of adult human predentin is:
|
a. 2 to 6
micrometers |
|
37
|
The hydroxyapatite crystals are formed along the
randomly distributed fibers in intertubular dentin with their long axes oriented __________ to the collagen fibers. |
Parallel to the tubule
|
|
38
|
During decalcification the type of dentin that is
lost is |
Peritubular dentin
|
|
39
|
The newly formed dentin is referred as
|
Predentin
|
|
40
|
The unmineralized dentin is:
|
Predentin
|
|
41
|
The odontoblastic processes are largest at the:
|
Pulpal end
|
|
42
|
The length and diameter of odontoblast cell bodies
are approximately: |
7 and 40 micrometers.
The odontoblastic processes are about one
micrometer and 200 to 300 micrometer in length. |
|
43
|
The odonoblastic process is composed of:
|
Microtubules and small filaments
|
|
44
|
The first ever synthesized dentin in a tooth is
referred as: |
Mantle dentin.
It is the outermost peripheral part of primary
dentin. |
|
45
|
The width of mantle dentin is about:
|
20 micrometers.
The width of coronal mantle dentin may be up to 150
micrometer thick. |
|
46
|
The area of initial dentin matrix formation is
observed as: |
Mantle dentin
|
|
47
|
The dentin formed prior to root completion is called
as: |
Primary dentin.
The dentin formed prior to root completion is
primary dentin, the bulk of which is the circumpulpal dentin. The dentin formed after root completion is the secondary dentin. Tertiary dentin is formed in response to noxious stimuli. |
|
48
|
The dentin formed after root completion is referred
as: |
Secondary dentin
|
|
49
|
The junction of primary and secondary dentin is
marked by: |
Sharp bend. Schreger line
|
|
50
|
The fine lines or striations in dentin are referred
as: |
Imbrication lines or incremental lines of von
Ebner. |
|
51
|
The incremental lines of von Ebner reflect the:
|
Daily rhythmic pattern of dentin matrix deposition.
It is about 4 to 8 micrometer in crown and still less in roots. Recent studies have proved that each incremental line of von Ebner are actually 20 micrometer apart and represent a 5 day increment. |
|
52
|
The lines of von Ebner run:
|
Right angle to dentinal tubules
|
|
53
|
Accentuated lines of von Ebner are referred as:
|
Contour lines of Owens
|
|
54
|
The area of hypomineralization between globules of
calcification is referred to as: |
Interglobular dentin
|
|
55
|
Interglobular dentin is found:
|
In circumpulpal dentin
|
|
56
|
In interglobular dentin the dentinal tubules pass:
|
Uninterruptedly through the matrix
|
|
57
|
The interglobular dentin is an area affected by a
defect of: |
Mineralization
|
|
58
|
In transmitted light, in root dentin, the zone
adjacent to cementum is: |
Tomes granular layer
|
|
59
|
The reason for the appearance of Tomes granular
layer is: |
Looping of distal portion of dentinal tubules
|
|
60
|
The theories that explain the pain transmission
through dentin are |
Direct neural transmission theory; Hydrodynamic
theory; Transduction theory |
|
61
|
The most popular and widely accepted theory of the
pain transmission through dentin is: |
Hydrodynamic theory
|
|
62
|
The theory in which the existence of dental lymph
is suggested is: |
Hydrodynamic theory
|
|
63
|
The theory in which the existence of
neurotransmitter vesicles inside dentinal tubules was suggested is: |
Transduction theory
|
|
64
|
Dentin is a vital tissue because it
|
Contains odontoblasts and its processes
|
|
65
|
The injured odontoblast processes synthesize:
|
Reparative dentin
|
|
66
|
Dead tracts appear black in:
|
Transmitted light
|
|
67
|
Numerous nerve endings are seen in:
|
Predentin. From pulp nerve endings extend up to a
level of 100 – 150 micrometers. |
|
68
|
Sclerotic dentin is found generally in teeth
of: |
Aged
|
|
69
|
Sclerotic dentin is formed due to:
|
Occlusion of the dentinal tubules with
hydroxyapatite |
|
70
|
Dentin formation begins at:
|
The cusp tip & incisal edge region
|
|
71
|
The daily increments of dentin formed are
approximately: |
4 micrometers.
This is in the primary dentin and it is one
micrometer per day in secondary dentin. Tertiary dentin formation rate depends on the stimulus and is some times more than 5 micrometers per day. |
|
72
|
The common pattern of mineralization in normal
dentin is: |
Linear & globular
|
|
73
|
Dentin formation is a function of:
|
Dental papilla cells
|
|
74
|
The cells of the dental papilla are of:
|
Ectomesenchymal origin
|
|
75
|
Dentin is produced by:
|
Odontoblasts
|
|
76
|
The initial site of dentin deposition will mark the
position of the: |
Dentinoenamel junction
|
|
77
|
Dentin formation takes place:
|
Before enamel formation
|
|
78
|
With age the pulp chamber is reduced in size due to
the deposition of (In absence of any pathology): |
Secondary dentin
|
|
79
|
The enzyme that is essential for formation of the
dentin is: |
Alkaline phosphatase
|
|
80
|
Dentin formation begins at:
|
Late bell stage
|
|
81
|
In multicusped teeth, the formation of dentin
begins: |
Independently.
It is independently occurring at the site of future
cusp tips and spreads down as each flank are fused. |
|
82
|
The amount of dentin deposited as tooth reaches its
functional position in the occlusion is: |
Two third of root dentin.
As the tooth reaches the occlusion, only two third
of the root dentin is deposited. After eruption the entire root dentin is deposited. This takes approximately 18 months in deciduous dentition and 2 to 3 years in permanent dentition after teeth erupts in to the oral cavity. |
|
83
|
A progressive reduction in a normal pulp cavity size
is associated with: |
Secondary dentin.
Tertiary dentin is associated with pathological or
aging process. |
|
84
|
The acellular zone between dental papilla and inner
enamel epithelium is eliminated by the: |
Odontoblasts.
It is eliminated by the differentiating odontoblasts
which increase in size and occupy this zone. |
|
85
|
The component of the ground substance that has been
found to transfer the inductive ability of the inner enamel epithelium to the superficial dental papillary cells is: |
Heparan sulfate.
The growth factors such as the TGF beta-1, BMP2, IGF
have been identified as the factors that are secreted by the inner enamel epithelium to induce odontoblast differentiation. |
|
86
|
The organic matrix of mantle dentin contains an
aperiodic collagen belonging to: |
Type VII collagen
|
|
87
|
Matrix vesicles essential for mineralization of
dentin is secreted by: |
Odontoblasts
|
|
88
|
The phosphoprotein that is unique to circumpulpal
dentin is the: |
Phosphoporyn.
It is absent in Predentin and mantle dentin and is
associated with mineralization. |
|
89
|
Diffence between Predentin and dentin:
|
Less or no mineralization;
Higher amount of proteoglycans; Having higher
quantities of chondroitin 6 sulfate. |
|
90
|
During mantle dentin formation, the blood
capillaries are found in the: |
Sub-odontoblastic layer.
During circumpulpal dentinogenesis, these
capillaries are bound between the odontoblastic layers and after odontogenesis they become sub-odontoblastic in position. |
|
91
|
Largest of interglobular dentin are formed in the:
|
At areas of fast dentin deposition.
Though the largest of interglobular dentin are seen
just below the mantle dentin in the circumpulpal dentin, they are seen only when the rate of dentin deposition is the fastest. |
|
92
|
The difference in coronal dentin and root dentin
is: |
Orientation in collagen molecule;
Phosphoryn content is less in root dentin; Rate of
deposition is slower in roots |
|
93
|
Odontoblasts move or retract in:
|
Centripetally
|
|
94
|
The amount of mineral phase that is within the
collagen is about: |
56%
|
|
95
|
When the cells forming tertiary dentin are included
in to the dentin itself, it is called: |
Osteodentin
|
|
96
|
The first formed collagen in mantle dentinogenesis
is deposited near the Hertwig’s epithelial root sheath’s basal lamina in a: |
Parallel fashion.
In coronal mantle dentinogenesis, the first formed
collagen fibers are deposited at right angles to the basement membrane. |
Prof. Rooban Thavarajah
Oral and Maxillofacial Pathologist
List