Exam 3 - Dentin Pulp Complex I Colombo Flashcards

1
Q

Mineralized protective component of the tooth is called:

A

Enamel

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2
Q

Mineralized structural component of the tooth is called:

A

Dentin

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3
Q

Main cellular component of the tooth is:

A

Pulp

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4
Q

Dentin composition is highly analogous to ____, but:

A

Bone; but slightly different composition and highly different anatomy

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5
Q

The crown is covered by:

A

Enamel

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6
Q

The root is covered by:

A

Cementum

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7
Q

Dentin composition by weight

A
  • inorganic material: 70%
  • organic material: 20%
  • water: 10%
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8
Q

Dentin composition by volume

A
  • inorganic material: 45%
  • organic material: 33%
  • water: 22%
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9
Q

Inorganic material in dentin (and enamel, bone, cementum) is called:

A

Hydroxyapatite

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10
Q

The water in dentin is also termed:

A

Physiological fluid

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11
Q

What is the chemical formula for hydroxyapatite?

A

Ca5(PO4)3(OH)

x2 per crystal unit cell

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12
Q

Hydroxyapatite is effectively a:

A

Calcium phosphate crystal

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13
Q

___ can replace the OH in hydroxyapatite

A

Fluoride (creates fluorapatite)

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14
Q

Besides fluoride, what other ions can replace the OH of hydroxyapatite?

A
  • zinc
  • magnesium
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15
Q

Hydroxyapatite crystals are arranged in _____

A

Rectangular plates

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16
Q

True or false: dentin is somewhat harder than bone

A

True (Knoop number 68, bone is 50)

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17
Q

True or false: enamel is much harder than dentin or bone

A

True - Knoop number 343

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18
Q

Why is enamel much harder than dentin?

A

Due to how the HA is arranged

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19
Q

Organic material of dentin is made of:

A
  • 90% collagen
  • 10% Non-collagenous proteins
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20
Q

Main type of collagen found in dentin

A

Collagen type 1 (also some type 3 and type 5)

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21
Q

The organic material secreted by dentin creates the _____ upon which HA is laid down

A

fibrillar collagen scaffold

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22
Q

Dentin specific proteins (in the organic component)

A
  • Dentin matrix protein 1 (DMP-1)
  • Dentin Sialophosphoprotein (DSPP)
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23
Q

DSPP is further cleaved by ____ into:

A

BMP-1; DSP, DPP, DGP

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24
Q

DSP is a ____ expressed in ____

A

proteoglycan; dentinal tubules

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25
Q

____ may act to prevent mineralization in tubules

A

DSP

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26
Q

DGP is a _____ and may have a role in ____ (unknown)

A

Glycoprotein; biomineralization

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27
Q

DPP binds ____ to initiate HA formation and is attached to ____

A

Lots of Ca2+; collagen

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28
Q

DPP is attached to ____

A

Collagen

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29
Q

____ is not thought to be glycosylated

A

DPP

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30
Q

____ is located on the N terminus of the DSPP protein

A

DSP

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31
Q

____ is located on the C terminus of the DSPP protein

A

DPP

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32
Q

Defects in DSPP can cause:

A

Dentinogenesis imperfecta Types II and III

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33
Q

Type 1 Dentinogenesis results from:

A

Osteogenesis imperfecta (defect in type 1 collagen)

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34
Q

Both type 1 and type 2 dentinogenesis imperfecta cause:

A

Pulp chambers to be filled with abnormal dentin

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35
Q

True or false: Type II Dentinogenesis imperfecta is associated with osteogenesis imperfecta

A

False (Type 1 can result from OI)

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36
Q

Type III Dentinogenesis imperfecta is associated with:

A
  • Enlarged pulp chambers
  • hypo-mineralization
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37
Q

Type III dentinogenesis imperfecta is caused possibly due to:

A

Failure of DSPP expression

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38
Q

Dentin is synthesized by _____

A

Odontoblasts

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39
Q

What lines the pulp chamber?

A

Odontoblasts

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40
Q

Odontoblasts are ____ cells which extend _____ into the dentin through tubules

A

Polarized; cellular projections

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41
Q

The dentin-pulp complex arises from:

A

Dental papilla

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42
Q

Initial differentiation of dentin formation occurs after:

A

Critical interaction with the inner enamel epithelium

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43
Q

When odontoblasts first differentiate, they fill the ___ zone between the ____ and ____

A

Acellular; IEE and dental papilla

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44
Q

Vascular support arises from:

A

Dental papilla

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45
Q

Signal for ameloblasts to form enamel

A

Predentin formation

(dentin always formed before enamel!)

46
Q

DEJ

A

Dentin-enamel junction; interface between the enamel and dentin where they are in direct apposition

47
Q

The edge of the DEJ is:

A

Scalloped

48
Q

The shape of the DEJ is important for:

A
  • defining the shape of the crown
  • keeping dentin directly attached to enamel during loading, preventing shearing
49
Q

The DEJ is bound together by a merging of _____

A

enamel HA and dentin HA crystals in ridges

50
Q

First layer of dentin formed is called ____ closest to the DEJ

A

Mantle dentin

51
Q

What are von Korff’s fibers

A

Collagen III fibers associated with fibronectin during dentin formation

52
Q

Von Korff’s fibers extend toward the _____ and branch into the ___ of the developing matrix to form the DEJ with a ____

A

IEE; ground substance; scalloped edge

53
Q

Developing odontoblasts extend processes called ____ into the developing matrix which is a ____ system and secreting dentin matrix components in ____

A

Tome’s fibers; tubule; matrix vesicles

54
Q

Penetration of the IEE by odontoblast projections form:

A

Enamel spindles

55
Q

Odontoblasts produce matrix moving away or toward the DEJ?

A

Away from the DEJ

56
Q

Tomes’ fiber will eventually become:

A

Odontoblast process

57
Q

Dentin starts as:

A

Non-mineralized organic matrix (predentin)

58
Q

Odontoblasts: Mineralization starts within ____ and deposited along the ____

A

secreted matrix vesicles; future DEJ

59
Q

What happens to matrix vesicles secreted by odontoblasts?

A

They rupture and released mineralized matrix crystals to form non-tubular mantle dentin

60
Q

Tubular primary dentin is formed after the formation of ____ and is regulated by ______

A

Mantle dentin; non-collagenous matrix proteins

61
Q

After the DEJ is formed, ____ dentin formation begins

A

Circumpulpal (dentin surrounding the pulp chamber)

62
Q

What initiates root odontoblast formation?

A

HERS

63
Q

HERS eventually breaks into:

A

Cell Rests of Malassez

64
Q

True or false: root dentin formation is very similar to coronal dentin formation

A

True

65
Q

True or false: there is no mingling of dentin collagen with cementum collagen

A

False - there is some

66
Q

Primary dentin

A
  • First dentin formed during development
  • comprises the mantle dentin and initial deposition of circumpulpal dentin
67
Q

____ dentin is produced throughout life

A

Secondary

68
Q

Secondary dentin is continuous with:

A

Primary dentin

but histologically distinct

69
Q

Coronal dentin tubules have a ___ curve; root dentin tubules are ____

A

Sigmoidal; straighter

70
Q

There is greater secondary dentin deposition in around ____ which causes pulpal ____

A

Roof and floor; recession

71
Q

Predentin is _____ distinct

A

Histologically (not yet mineralized)

72
Q

Tertiary dentin is produced in response to:

A

Insult

73
Q

Tertiary dentin can have ____ but often does not. If they are present, they are often ____ and can include ____

A

Tubules; disordered; cells

74
Q

Tertiary dentin function

A
  • acts to seal off dentinal tubules
  • form bridges between dentin and resorations or in response to trauma
75
Q

Tertiary dentin can be either ____ or ____

A
  • reactionary
  • reparative
76
Q

In reactionary tertiary dentin formation, does trama damage odontoblasts?

A

No

77
Q

Reparative dentin is ____ to odontoblasts; however, it involves recruitment and differentiation of ____ to form new ____

A

Damaging; mesenchymal cells; odontoblasts

78
Q

During reparative dentin formation, there is more ___ and less ____

A

More BSP and OP
Less DSP and DMP-1

79
Q

Mantle dentin

A

First dentin formed at the DEJ

80
Q

Predentin

A

Unmineralized dentin matrix (proteins)

81
Q

Circumpulpal dentin

A

dentin formed around the pulp after the mantle dentin before roots fully formed

82
Q

Secondary dentin

A

dentin formed subsequent to root formation; forms throughout the life of a tooth

83
Q

Primary feature of dentin macrostructure

A

Tubules

84
Q

3 main structures in dentin

A
  • dentin tubules with OD process
  • Peritubular dentin
  • intertubular dentin
85
Q

Dentinal tubules run from ____ to ___

A

DEJ; OD layer of the pulp

86
Q

Dentinal tubules are filled with

A

Fluid

87
Q

Tubule density is high or low?

A

Very high; 59K-76K/mm2 in apposition to the pulp (half of that at the DEJ)

88
Q

Dentinal tubules are surround by collars of:

A

Highly calcified peritubular dentin

89
Q

Dentinal tubules are separated by:

A

Intertubular dentin (collagen I fibrils arranged perpendicular to tubules)

90
Q

____ provide mechanical support to the enamel during loading

A

dentinal tubules

91
Q

Dead tracts

A

have an end sealed off but otherwise empty, appear black in ground sections

92
Q

Sclerotic dentin occurs when:

A

Tubules are totally filled, has a glassy translucent appearance in ground sections

93
Q

As peritubular dentin is deposited, ____ naturally occur

A

Dead tracts/sclerotic dentin

starts apically, continues toward the crown with age

94
Q

Interglobular dentin

A
  • areas of hypomineralized dentin
  • formed when fusion of mineral contain vesicles fails
95
Q

____ can be associated with vitamin D deficiency or fluoride exposure during initial dentin formation

A

Interglobular dentin

96
Q

Interglobular dentin is more common near

A

Mantle dentin

97
Q

Is matrix present in interglobular dentin?

A

Yes

98
Q

True or false: enamel spindles are the same as enamel

A

False - may have trace amounts of dentin (collagen)

99
Q

Where do enamel spindles usually appear?

A

cusp tips/incisal edges

100
Q

Cyclical deposition of primary dentin forms ____ which can be seen at 20 micron increments

A

Lines of von ebner

101
Q

___ is asymmetrically deposited and more slowly

A

Secondary dentin

102
Q

Contour lines of owen is equivalent to

A

Striae of Retzius

103
Q

____ dentin contains the granular layer of tomes

A

Root

104
Q

Granular layer of tomes becomes more granular towards:

A

Apical end

105
Q

Granular layer of tomes possible forms due to:

A
  • hypomineralized areas of dentin (similar to interglobular dentin)
  • part of looped dentinal tubules found in the root sections, artifact of sectioning
  • specialized dentin structures which form part of dentin/cementum junction
106
Q

Hyaline layer of hope-well smith

A

dentin next to cementodentinal junction

107
Q

Last part of root dentin which mineralizes

A

Hyaline layer of hopewell smith

108
Q

Hyaline layer of hopewell smith provides attachment point for

A

Periodontal ligament fibers

109
Q

What is external to the granular layer of tomes?

A

Hyaline layer of hopewell smith

110
Q

Hyaline layer of hopewell smith contains:

A

mingled enamel matrix proteins with dentin matrix proteins