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**Oral Biology > Dentin and Pulp Complex I > Flashcards

Dentin and Pulp Complex I Flashcards

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1
Q

Which part of the tooth is Protective?

A

Enamel

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2
Q

What part of the tooth is the structural component?

A

Dentin

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3
Q

What is the main cellular component of the tooth?

A

Pulp

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4
Q

What is the composition of dentin?

A

70% Inorganic
20% Organic
10% Water

*Highly analogous to bone

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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

What is the “water” that helps compose the dentin?

A

Physiological fluid

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8
Q

What is the inorganic material of dentin?

A

Hydroxyapatite

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9
Q

What can fluoride replace in the hydroxyapatite crystal?

A

OH

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10
Q

What other ions can replace components of hydroxyapatite?

A

Magnesium and Zinc

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11
Q

In Dentin, what are the dimensions of the HA crystals?

A

60-70 nm Long
20-30 nm wide
3-4 nm thick

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12
Q

What are the respective Knoop Numbers of Dentin, Enamel, and cortical bone?

A

Dentin: 68
Enamel: 343
Bone: 50

**This is a measure of the hardness of the substance

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13
Q

Organic components make up 20% of dentin. What is the make up of the organic component itself?

A

90% collagen (mostly I, some III and V)

10% Non-collagenous proteins

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14
Q

What is the purpose of the collagen in the organic material?

A

Fibrillar collagen scaffold upon which HA crystals are laid down

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15
Q

What Non-collagenous proteins do bone and dentin have in common?

A
  1. Bone Sialoprotein (BSP)
  2. Osteopontin (OP)
  3. Osteocalcin (OC)
  4. Osteonecdtin (ON)
  5. Matrix Extracellular Phosphoglycoprotein
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16
Q

What additional proteins does dentin have that are not found in bone in high abundance?

A
  1. Dentin Matrix Protein-1 (DMP-1)
  2. Dentin Sialophosphoprotein (DSPP)
    - Further cleaved into other proteins**
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17
Q

What proteins is DSPP cleaved into?

A
  1. Dentin Sialoprotein (DSP)
  2. Dentin Phosphoprotein (DPP)
  3. Dentin Glycoprotein (DG)
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18
Q

What cleaves DSPP into it’s three derivative proteins?

A

BMP-1

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19
Q

DSP is a ________ that is expressed in _________ and may act to prevent _________ and is similar to ______

A
  1. Proteoglycan
  2. Dentinal Tubules
  3. Mineralization
  4. DMP-1
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20
Q

DGP is a __________ that may have a role in ________ , but really it’s function is ________

A
  1. Glycoprotein
  2. Biomineralization
  3. Unknown
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21
Q

DPP binds lots of _______ and initiates ________. It is attached to _____ and is not thought to be _______

A
  1. Ca2+
  2. HA formation
  3. Collagen
  4. glycosylated
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22
Q

What do Defects in DSPP cause?

A

Dentinogenesis Imperfecta types II and III

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23
Q

What is type I dentinogenesis Imperfecta and what causes it?

A
  • Pulp chambers filled with abnormal dentin
  • Results from OI (defect in collagen I)

**OI: osteogenesis imperfecta

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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

What is Type II Dentinogenesis imperfecta?

A
  • Pulp chambers filled with abnormal dentin

- Caused by DSPP defect

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27
Q

What is Type III dentinogenesis imperfecta?

A
  • Enlarged pulp chambers
  • Hypo-mineralization
  • Possibly failure of DSPP expression
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28
Q

Dentin is synthesized by _______ which line the __________

A
  1. Odontoblasts

2. Pulp Chamber

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29
Q

What is the origin of dentin cells?

A

Mesenchyme

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30
Q

Odontoblasts are ________ cells which extend cellular ______ into the dentin through ______

A
  1. Polarized
  2. Projections
  3. Tubules
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31
Q

What gives rise to the dentin-pulp complex from an embryological perspective?

A

Dental Papilla

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32
Q

What is described as a critical interaction with the inner enamel epithelium?

A

Initial differentiation

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33
Q

Odontoblasts differentiate and fill the _________ between the _____ and the _______

A
  1. Acellular zone
  2. IEE
  3. Dental papilla
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34
Q

The interface between the enamel and dentin is called the _______

A

DEJ

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35
Q

Describe the edge of the DEJ

A

Scalloped

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36
Q

Why is the shape of the DEJ so critical?

A
  1. Defines the shape of the crown

2. Keeps dentin directly attached to enamel during loading (no shearing)

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37
Q

Describe the binding of the DEJ

A

Bound together by a merging of enamel HA and dentin HA crystals in ridges, which are most pronounced

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38
Q

T/F Odondoblasts conintue to synthesize dentin through the life of the tooth

A

TRUE

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39
Q

T/F Dental/enamel Shearing is bad

A

TRUE

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40
Q

What is the first layer of dentin called that is formed closest to the DEJ?

A

Mantle Dentin

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41
Q

What are Von Korff’s fibers?

A

.1-.2mm collagen III fibrils associated with fibronectins

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42
Q

What is formed when dentin penetrates the IEE?

A

Enamel Spindles

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43
Q

Developing odontoblasts begin extending processes into the developing matrix. What are those processes called?

A

Tomes’ Fibers

44
Q

What do the ondontoblastic process in the developing matrix secrete?

A

Dentin Matrix components

45
Q

How do Von Korff’s fibers contribute to the formation of the DEJ with the ‘scalloped’ edge?

A

The extend towards the IEE and branch into the ground substance of the developing matrix

46
Q

Odontoblasts produce matrix as it moves away from the _______

A

DEJ

47
Q

As Odontoblasts move away from the DEJ, they leave behind ________

A

Tomes’ Fiber

48
Q

What does tomes’ fiber eventually become?

A

Odontoblast Process

49
Q

Dentin starts as what?

A

Predentin which is a non-mineralized organic matrix

50
Q

Mineralization of dentin starts within ________, which are deposited along the ______

A
  1. OD secreted vesicles

2. Future DEJ

51
Q

Secreted matrix vesicles rupture and release ________

A

Mineralized matrix crystals

52
Q

T/F Mantle Dentin is Tubular

A

FALSE

53
Q

What is Mantle Dentin formed by_______

A

the mineralized matrix crystals released from matrix vesicles

54
Q

After the formation of mantle dentin, what regulates subsequent dentin formation and what does it result in?

A
  1. Non-collagenous matrix proteins

2. Tubular primary dentin

55
Q

When does the formation of Circumpulpal dentin begin?

A

After DEJ formation

56
Q

To form root dentin, what initiates odontoblast differentiation?

A

Hertwig’s Epithelial Rooth Sheath

57
Q

What does HERS eventually break down into?

A

Epithelial rests of Malassez

58
Q

T/F the formation of Root dentin is very similar to the formation of Coronal Dentin

A

TRUE

59
Q

What are some possible differences between root dentin and coronal dentin formation?

A
  1. Mainly anatomical

2. Some mingling of dentin collagen with cementum collagen

60
Q

What are the 3 types of dentin?

A

Primary
Secondary
Tertiary

61
Q

Describe Primary Dentin?

A
  • The first dentin formed during development

- Compromised the mantle dentin and initial deposition of circumpulpal dentin

62
Q

Describe secondary dentin?

A
  • Tubular dentin laid down subsequent to root formation
  • Produced throughout life
  • Continous with primary dentin, but histologically distinct
63
Q

What is one morphologic difference between coronal dentin and root dentin?

A

Coronal dentin tubules have a sigmoidal curve, root dentin tubules are much straighter

64
Q

What is caused by greater secondary dentin deposition around roof and floor?

A

Pulpal recession

65
Q

Describe pre-dentin

A

Not yet mineralized dentin, histologically distinct from other types

66
Q

Why would tertiary dentin be produced?

A

In response to insult

67
Q

Can tertiary dentin have tubules?

A

Yes, but it often does not.

If Tubules are present, they are often disordered and can ‘include’ cells

68
Q

Tertiary dentin acts to seal off _________ or to form bridges between dentin and __________ , or in response to ______

A
  1. Dentinal tubules
  2. Restorations
  3. Trauma
69
Q

What is reactionary Dentin?

A
  • Tertiary dentin

- Forms in response to trauma that does not damage odontoblasts

70
Q

What is Reparative Dentin?

A
  • Tertiary Dentin

- Forms in response to trauma that damages Odontoblasts

71
Q

Formation of reparative dentin involves the recruitment and differentiation of what?

A

Mesenchymal cells, which form new odontoblasts

72
Q

In the formation of reparative dentin you have less DSP and DMP-1, and more BSP and OP T/F

A

TRUE

73
Q

What is the primary structure of the Dentin Macrostructure?

A

Tubules

74
Q

Within the context of Dentin Macrostructure, what are the 3 main structures in dentin?

A
  1. Dentin Tubules (With OD process)
  2. Peritubular Dentin
  3. Intertubular Dentin
75
Q

Dentinal tubules run from ______ to _______

A
  1. The DEJ

2. OD layer of the pulp

76
Q

T/F Dentinal Tubules are fluid filled

A

TRUE

77
Q

Describe the density of dentinal tubules

A
  • Very high
  • 59k-76k/mm squared in apposition to the pulp
  • Around half of that density at the DEJ
78
Q

Dentinal tubules are surrounded by highly calcified collars of ______

A

Peritubular dentin

79
Q

Dentinal Tubules are separated by _______

A

Intertubular Dentin

80
Q

Describe Intertubular dentin

A

50-200nm collagen I fibrils arranged perpendicular to tubulese

81
Q

Dentinal tubules can form secondary branches, where are they most likely to do this?

A

In the root

82
Q

T/F Dentinal tubules provide mechanical support to the enamel during loading

A

TRUE

83
Q

T/F Dentinal Tubules have implications for the formation of carious lesions

A

TRUE

84
Q

After breaking through the DEJ, bacteria move _______ through ________

A
  1. Rapidly

2. Tubules

85
Q

What do bacteria do to the mineralized matrix and protein scaffold?

A
  1. Mineralized matrix is liquefied

2. Protein scaffold eroded

86
Q

What is the response of dentin to the infiltration of bacteria?

A

Formation of tertiary dentin to occlude tubules

87
Q

What are “dead tracts” in ground sections?

A
  • Trapped air in empty tubules

- Sealed off after odontoblast death (insult of apoptosis)

88
Q

What is Sclerotic dentin?

A

It is a collective term for tubules that have become occluded

89
Q

Describe the appearance of Sclerotic dentin

A

Glassy, translucent appearance ( in a ground section)

90
Q

How does sclerotic dentin happen?

A
  • Occurs naturally, with age as peritubular dentin is deposited
  • Can occur by:
    • Mineralization only
    • Diffuse mineralization around a living OD process
    • Mineralization of the cellular process and the collagen fibers along the inside of the tubule
91
Q

In what direction would sclerotic dentin form?

A

Starts apically, continues toward the crown with age

92
Q

What is Interglobular dentin?

A

Areas of Hypomineralized dentin

93
Q

When would interglobular dentin form?

A

When fusion of mineral containing vesicles fail

94
Q

A vitamin D deficiency or fluoride exposure during initial dentin formation can be associated with what?

A

Interglobular dentin formation

95
Q

Where would you more commonly find interglobular dentin?

A

Near Mantle dentin

96
Q

Tubules often run through areas of _________, matrix is present

A

Interglobular dentin

97
Q

Dentin matrix is deposited contiually at rate of _______

A

4um/day

98
Q

Every _ days, there is a layer deposited which has a noticeably different orientation of _________

A

Collagen fibers

99
Q

The deposition of different orientation of collagen fibers every 5 days forms what?

A

Lines of Von Ebner

*Which can be seen at around 20um intervals

100
Q

Every 12 hours around ____ of mineralization occurs

A

2um

101
Q

Secondary dentin is deposited ________, more slowly

A

asymmetrically

102
Q

What are Contour lines of Owen?

A

Enhanced lines that indicate disruption of tooth formation (Like neonatal line)

**They are equivalent to striae of retzius in enamel, which also has a neonatal line

103
Q

T/F Tetracycline banding is influenced by/follows the pattern of the cyclical deposition of primary dentin

A

TRUE

104
Q

What does the granular layer of Tomes look like?

A

Funny looking dots around the roots of ground sections

105
Q

T/F The Granular Layer of Tomes gets more granular toward the apical end of the tooth

A

TRUE

106
Q

What are 3 possible explanations of what the Granular Layer of Tomes is?

A
  1. Hypomineralized areas of dentin, similar to interglobular dentin
  2. Part of looped dentinal tubules found in the root sections, an artifact of sectioning
  3. Specialized dentin structures which form part of the dentin-cementum junction

**Oral Biology (10 decks)

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