QUIZ 3 Dentin Pulp Complex I Flashcards

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1
Q

dentin is the main ___ material of the tooth

A

structural

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2
Q

the structure of the dentin is directly linked to what?

A

its primary function of supporting tooth loading

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3
Q

briefly describe enamel, dentin, and pulp

A
  • enamel
    • mineralized protective component
  • dentin
    • mineralized structural component
  • pulp
    • main cellular component
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4
Q

dentin is highly analogous to ___, but slightly different composition and highly different anatomy

A

bone

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5
Q

the crown is covered by ___, and the root is covered by ___

A
  • enamel
  • cementum
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6
Q

dentin is ___% inorganic material, ___% organic material, and ___% water

A

70%, 20%, 10%

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7
Q

hydroxyapatite makes up the ___ component of dentin

A

inorganic material

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8
Q

what is the formula for hydroxyapatite, and how many molecules of HA are in each crystal unit cell?

A

Ca5(PO4)3(OH)

2 per crystal unit cell

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9
Q

HA is effectively a ___ ___ crystal

A

calcium phosphate

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10
Q

fluoride can replace the ___ in hydroxyapatite, creating ___

A
  • OH
  • fluoroapatite
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11
Q

besides fluoride, what else can replace the OH in hydroxyapatite in dentin?

A

zinc, magnesium, and others

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12
Q

in dentin, HA crystals are what shape?

A

flattened rectangular plates

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13
Q

what are the dimensions of HA in dentin?

A
  • 60-70 nm long
  • 20-30 nm wide
  • 3-4 nm thick
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14
Q

dentin is somewhat harder than ___. what are the knoop numbers for dentin, enamel, and bone?

A
  • bone
  • knoop numbers:
    • dentin - 68
    • enamel - 343
    • cortical bone - 50
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15
Q

what is the composition of the organic material component of dentin?

A
  • 90% collagen
    • mostly I, some III and V
  • 10% non-collagenous proteins
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16
Q

describe the collagen component of the organic component of dentin

A
  • 90%
  • mostly collagen I, some III and V
  • fibrillar collagen scaffold upon which HA crystals are laid down
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17
Q

what are the 5 non-collagenous proteins that dentin has in common with bone?

A
  • bone sialoprotein (BSP)
  • osteopontin (OP)
  • osteocalcin (OC)
  • osteonectin (ON)
  • matrix extracellular phosphoglycoprotein
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18
Q

what are the 2 main dentin specific non-collagenous proteins?

A
  • dentin matrix protein-1 (DMP-1)
  • dentin sialophosphoprotein (DSPP)
  • *still found in bone, but only trace amounts
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19
Q

DSPP can be further cleaved into what 3 functional proteins?

A
  • dentin sialoprotein (DSP)
  • dentin phosphoprotein (DPP)
  • dentin glycoprotein (DG)
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20
Q

DSPP is cleaved rapidly by what enzyme?

A

BMP-1

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21
Q

describe DSP

A
  • proteoglycan
  • expressed in dentinal tubules
  • may act to prevent mineralization
  • similar to DMP-1
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22
Q

describe DGP

A
  • glycoprotein
  • role in biomineralization?
  • unknown function
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23
Q

describe DPP

A
  • binds lots of calcium, initiates HA formation
  • attached to collagen
  • not thought to be glycosylated
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24
Q

DSP comes from which end of DSPP?

A

N terminus

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25
Q

DPP comes from which end of DSPP?

A

C terminus

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26
Q

defects in DSPP can cause what?

A

dentinogenesis imperfecta types II and III

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27
Q

which dentinogenesis imperfecta type is described by the following:

results from OI (defect in collagen I), pulp chambers filled with abnormal dentin

A

type I (not a result of defects in DSPP)

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28
Q

which dentinogenesis imperfecta type is describe by the following?

not associated with osteogenesis imperfecta (DSPP defect), pulp chambers filled with abnormal dentin

A

type II

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29
Q

which dentinogenesis imperfecta type is describe by the following?

enlarged pulp chambers, hypo-mineralization, possibly failure of DSPP expression

A

type III

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30
Q

dentin is synthesized by ___, which line the pulp chamber

A

odontoblasts

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31
Q

odontoblasts have a ___ origin

A

mesenchymal

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32
Q

odontoblasts are ___ cells which extend cellular projections into the dentin through ___

A
  • polarized
  • tubules
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33
Q

label this photo

A
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34
Q

the dentin-pulp complex arises from ___

A

dental papilla

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35
Q

in the development of dentin, odontoblasts differentiate and fill what?

A

the acellular zone between the IEE and dental papilla

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36
Q

is there vascular support for odontoblasts?

A

yes

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37
Q

in the development of dentin, initial differentiation involves the critical interaction with the ___

A

IEE

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38
Q

the ___ is the interface betwen the enamel and dentin, where they are in direct apposition

A

DEJ

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39
Q

the DEJ has a ___ edge

A

scalloped

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40
Q

why is the shape (scalloped) of the DEJ critical?

A
  • defines the shape of the crown
  • keeps dentin directly attached to enamel during loading (no shearing)
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41
Q

the DEJ is bound by a merging together of ___ and ___ in ridges, which are most pronounced under the ___

A
  • enamel HA crystals
  • dentin HA crystals
  • crown
42
Q

why is dentin/enamel shearing bad?

A

the structure of the tooth can break down and compromise the structural stability of the tooth

43
Q

which is the first layer of dentin formed?

A

mantle dentin, closts to the DEJ

44
Q

are there tubules in mantle dentin?

A

no

45
Q

what are von korff’s fibers?

A
  • 0.1-0.2 mm collage III fibers
  • associated with fibronectin
  • laid down by odontoblasts during dentin formation
46
Q

von korff’s fibers extend towards the ___ and branch into the ground substance of the developing matrix, forming the ___

A
  • IEE
  • DEJ (with scalloped edge)
47
Q

after von korff’s fibers form the DEJ, developing odontoblasts begin extending processes (___) into the developing matrix (___), and secreting dentin matrix components in ___

A
  • tomes’ fibers
  • tubule system
  • matrix vesicles
48
Q

odontoblasts produce matrix, and move away from the ___

A

DEJ

49
Q

when odontoblasts move away from the DEJ, they leave behind ___, which is the future odontoblast process

A

tomes’ fiber (not tomes’ process)

50
Q

dentin starts as ___ organic matrix

A

non-mineralized (aka predentin)

51
Q

mineralization of predentin starts within ___, deposited along the future DEJ

A

OD secreted matrix vesicles

52
Q

how is non-tubular mantle dentin formed?

A

secreted matrix vesicles rupture and release mineralized matrix crystals

53
Q

how is tubular primary dentin formed?

A

formed after non-tubular mantle dentin

non-collagenous matrix proteins regulate subsequent dentin formation

54
Q

after DEJ formation, ___ dentin formation begins

A

circumpulpal

55
Q

in the formation of root dentin, ___ initiates odontoblast differentiation

A

hertwig’s epithelial root sheath (HERS)

56
Q

after initiating odontoblast differentiation, HERS will eventually break into ___

A

cell rests of malassez

57
Q

root dentin formation is very similar to ___

A

coronal dentin formation

58
Q

what are the possible differences between coronal dentin formation and root dentin formation?

A
  • anatomical
  • some mingling of dentin collagen with cementum collagen
59
Q

___ is the first dentin formed during development.

A

primary dentin

all the dentin made before the roots are formed

60
Q

primary dentin is comprised of ___ and ___

A

the mantle dentin and the initial deposition of circumpulpal dentin

61
Q

___ is tubular dentin laid down subsequent to root formation

A

secondary dentin

62
Q

___ dentin is produced throughout life

A

secondary

63
Q

secondary dentin is continuous with primary dentin, but is ___ distinct

A

histologically

64
Q

coronal dentin tubules have a ___ curve, and root dentin tubules are ___

A
  • sigmoidal (due to odontoblast crowding)
  • much straighter
65
Q

there is greater secondary dentin deposition around where?

A

roof and floor (top and bottom of pulp chamber) - pulpal recession

66
Q

why is pre-dentin so easy to distinguish from other types of dentin histologically?

A

because it is the only type of dentin that is not mineralized

67
Q

___ is dentin produced in response to insult

A

tertiary dentin

68
Q

___ can have tubules, but often does not. if tubules are present, they are often ___

A
  • tertiary dentin
  • disordered
69
Q

tertiary dentin acts to seal off ___, or to form bridges between ___ and ___ or in response to ___

A
  • dentinal tubules
  • dentin
  • restorations
  • trauma
70
Q

what is the difference between reactionary and reparative tertiary dentin?

A
  • reactionary - trauma does not damage odontoblasts (mild stimulus)
  • reparative - trauma damages odontoblasts, involves recruitment and differentiation of mesenchymal cells, forming new odontoblasts (strong stimulus)
71
Q

tertiary dentin has less ___ and ___, and more ___ and ___

A
  • DSP and DMP-1
  • BSP and OP
72
Q

what is the primary feature of dentin macrostructure?

A

tubules

73
Q

what are the 3 main structures in dentin?

A
  • dentin tubules (with OD processes)
  • peritubular dentin (surrounds dentin tubules)
  • intertubular dentin (in between peritubular dentin)
74
Q

dentinal tubules run from the ___ to the ___

A

DEJ to the OD layer of the pulp

75
Q

do dentinal tubules have fluid?

A

yes, they are fluid-filled

76
Q

describe tubule density in apposition to the pulp vs DEJ

A
  • density is high in apposition to the pulp
    • 59K - 76K/mm2
  • around half at the DEJ
77
Q

dentinal tubules are surrounded by collars of ___

A

highly calcified peritubular dentin

78
Q

the dentinal tubules/ peritubular complexes are separated by ___

A

intertubular dentin, which is 50-200nm collagen I fibrils arranged perpendicular to tubules

79
Q

dentinal tubules can form ___, especially in the root

A

secondary branches

80
Q

dentinal tubules provide ___ to the enamel during loading

A

mechanical support

81
Q

after breaking through the ___, bacteria can move rapidly through the dentinal tubules

A

DEJ

82
Q

what happens to the matrix and protein scaffold when bacteria is introduced to dentin?

A

mineralized matrix is liquefied and protein scaffold is eroded

83
Q

what is the response to bacterial infiltration in the dentin?

A

formation of tertiary dentin to occlude tubules

84
Q

what are dead tracts?

A

seen in ground sections, they are trapped air in empty tubules - seald off after odontoblast death (insult or apoptosis)

histologically, they look black

85
Q

___ is a collective term for tubules that have become occluded

A

sclerotic dentin

86
Q

sclerotic dentin has a ___, ___ appearance in ground sections

A

glassy, translucent

87
Q

what is sclerotic dentin a result of?

A
  • occurs naturally, with age as peritubular dentin is deposited
  1. can occur by mineral deposition only
  2. diffuse mineralization around a living OD process
  3. or mineralization of the cellular process and the collagen fibers along the inside of the tubule
88
Q

sclerotic dentin starts ___, then continues towards the ___ with age

A
  • apically
  • crown
89
Q

___ are ares of hypomineralized dentin

A

interglobular dentin

90
Q

interglobular dentin is formed by the failure of the fusion of ___

A

mineral containing vesicles

91
Q

interglobular dentin can be associated with ___ deficiency or ___ exposure during initial dentin formation

A
  • vitamin D deficiency
  • fluoride exposure
92
Q

interglobular dentin is more common near ___ dentin

A

mantle dentin

93
Q

T or F:

tubules never run through areas of interglobular dentin

A

false

tubules often run through areas of interglobular dentin, where matrix is present

94
Q

dentin matrix is deposited continually at what rate?

A

4 micrometers/day

95
Q

every 5 days or so, there is a layer of primary dentin deposited which as a noticeably different orientation of ___

A

collagen fibers

96
Q

the different orientation of collagen fibers from the layer of primary dentin deposited every 5 days forms the ___, which can be seen around 20 micrometer intervals

A

lines of von ebner

97
Q

mineralization of primary dentin occurs at around what rate?

A

2 micrometers every 12 hours

98
Q

secondary dentin is ___ deposited, which is slower or faster than primary dentin deposition?

A
  • asymmetrically
  • slower
99
Q

what are contour lines of owen?

A
  • enhanced lines in dentin that indicate disruption of tooth formation (ie. neonatal line)
  • equivalent to the striae of retzius in the enamel (where there is also a neonatal line)
100
Q

what is the granular layer of tomes?

A

dots around the root dentin of ground sections

101
Q

the granular layer of tomes gets more granular toward the ___ end

A

apical

102
Q

describe possibilities of what granular layer of tomes is caused by

A
  • hypomineralized areas of the dentin, similar to interglobular dentin
  • part of looped dentinal tubules found in the root sections, an artifact of sectioning
  • specialized dentin structures which form part of the dentin-cementum junction