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Histopathology > Exam 2 - Dentin & Dentinogenesis > Flashcards

Exam 2 - Dentin & Dentinogenesis Flashcards

1
Q

Dentin is ____ mineralized than enamel.

A

LESS

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2
Q

Dentin is __% mineral/inorganic and __% organic, with __% water.

A

70; 20; 10

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3
Q

What type of collagen does dentin contain?

A

Type I, with trace Type III & V

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4
Q

50% of non-collagenous proteins in dentin are ____.

A

phosphoproteins

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5
Q

What non-collagenous proteins are present in dentin?

A 
sialoprotein
sialophosphoprotein
proteoglycans
glycosaminoglycans
osteonectin
osteopontin
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6
Q

Is Type I collagen in dentin the same as Type I in bone?

A

NO

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7
Q

T/F: Type I collagen in dentin has lower ratios of proline and hydroxyproline than Type I collagen in bone.

A

FALSE; dentin has higher ratios of proline and hydroxyproline than bone

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8
Q

T/F: Type I collagen in dentin has a higher prevalence of cross-linking than Type I collagen in bone.

A

TRUE

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9
Q

Does Type I collagen in dentin have a higher level of bound water than Type I collagen in bone?

A

YES

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10
Q

T/F: Hydroxyapatite crystals in dentin are highly organized, much like enamel.

A

FALSE; hydroxyapatite crystals in dentin are NOT organized like HA crystals in enamel - they are randomly oriented

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11
Q

Biglycan and Decorin are ____ non-collagenous proteins in dentin.

A

proteoglycans

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12
Q

Chondroitin-4-sulfate and chondroitin-6-sulfate are ____ non-collagenous proteins in dentin.

A

glycosaminoglycans

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13
Q

Gla-proteins, osteonectin, and osteopontin are all ___ matrix non-collagenous proteins.

A

dentin

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14
Q

____ contains the receptor-binding sequence “arginine-glycine-asparagine,” or the RGD binding complex.

A

Osteopontin

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15
Q

____ are gelatinous, undergo mineralization, and are necessary for initiation, mineralization and controlling the size of crystalline structures.

A

Matrix proteins

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16
Q

What are the 4 life cycle stages of odontoblasts?

A

1) Pre-odontoblast
2) Secretory odontoblast
3) Transitional odontoblast
4) Resting odontoblast

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17
Q

Where is the stimulus for ectomesenchymal cell differentiation into pre-odontoblasts derived from?

A

fibronectin (and some GF from the IEE)

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18
Q

Where is fibronectin found?

A

the basal lamina of the IEE

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19
Q

What substance must be present for ectomesenchymal cells to differentiate into pre-odontoblasts?

A

fibronectin

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20
Q

Pre-odontoblastic ____ receptors allow the cells to align themselves along the basal lamina, assume polarity, and differentiate into secretory cells.

A

fibronectin

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21
Q

Which life cycle stage of odontoblasts are the “functional odontoblasts?”

A

secretory odontoblasts

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22
Q

Secretory odontoblasts are ___ cells with extensive junctional complexes and gap junctions.

A

tall columnar

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23
Q

____ exhibit significant alkaline phosphatase activity which helps with mineralization of hydroxyapatite.

A

Secretory odontoblasts

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24
Q

What is the role of alkaline phosphatase?

A

mineralizes hydroxyapatite crystals

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25
Q

Secretory odontoblasts secrete type ___ collagen, and trace amounts of types __ and __.

A

I; III; V

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26
Q

What do secretory odontoblasts use for their mechanism of secretion?

A

secrete matrix vesicles

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27
Q

T/F: Odontoblasts make their own alkaline phosphatase and ameloblasts do not.

A

TRUE

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28
Q

What matrix vesicles do secretory odontoblasts secrete?

A 
phospholipids
alkaline phosphatase
phosphoproteins
pyrophosphatase
Ca2+ and PO4-
Annexin
HA crystal crystallites
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29
Q

____ mediates the flow of calcium into the matrix vesicle and also serves as a collagen receptor that binds matrix vesicles to collagen.

A

Annexin

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30
Q

What is the role of annexin in dentin?

A
  • mediates calcium flow into matrix vesicle

- serves as a collagen receptor that binds matrix vesicles to collagen

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31
Q

Which odontoblasts in the life cycle start to slow down and develop autophagic vacuoles?

A

transitional odontoblasts

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32
Q

____ are flat and have no ER or Golgi bodies present.

A

resting odontoblasts

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33
Q

What growth factors are secreted by the IEE?

A

transforming growth factor (TGF)
bone morphogenic proteins (BMP)
insulin-like growth factor (IGF)
fibroblast growth factor (FGF)

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34
Q

T/F: Complete differentiation requires a set number of cell divisions which allows cells to express appropriate receptors able to bind to growth factors.

A

TRUE

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35
Q

What does the last mitotic division of an odontoblast result in?

A

a mature odontoblast and a daughter cell that is forced into the sub-odontoblastic layer

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36
Q

The _____ layer has fully differentiated cells and lie right against the basement membrane.

A

dentin-forming

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37
Q

The ____ layer has cells that are blocked from the inductive influences of growth factors and are not fully differeniated.

A

subodontoblastic

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38
Q

Can cells of the subodontoblastic layer form dentin?

A

NO

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39
Q

What are the cells of the subodontoblastic layer limited to forming?

A

reparative odontoblasts

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40
Q

What is the 1st formed dentin?

A

mantle dentin

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41
Q

Mantle dentin is formed by ____ odontoblasts.

A

secretory

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42
Q

Mantle dentin matrix is composed of Type __ and __ collagen.

A

I; III

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43
Q

Collagen fibers are arranged ____ to the basal lamina of the IEE.

A

perpendicular

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44
Q

What does mantle dentin stimulate?

A

stimulates ameloblasts to secrete enamel

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45
Q

Organic dentinal matrix is deposited incrementally at a rate of __ to __ um per 24 hours.

A

4; 8

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46
Q

What are the incremental lines of dentin called?

A

lines of von Ebner

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47
Q

____ are incremental lines in dentin that represent the hesitations in matrix formation.

A

lines of von Ebner

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48
Q

Are lines of von Ebner hyper- or hypomineralized?

A

HYPOmineralized

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49
Q

When do these areas of hypomineralization (lines of von Ebner) occur?

A

every 4-20 days of matrix deposition

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50
Q

Deficiencies and irregularities in dentinogenesis, resulting in areas of hypomineralization appear as what structures?

A

neonatal line
lines of Owen
areas of interglobular dentin

51
Q

Exaggerated lines of von Ebner that occur during periods of altered cell metabolism may manifest as:

A

neonatal line - trauma from childbirth

lines of Owen - exaggerated lines from longer hesitation

52
Q

____ arise from trauma from childbirth.

A

Neonatal lines

53
Q

____ are exaggerated lines of von Ebner due to longer hesitation.

A

Lines of Owen

54
Q

Which teeth are neonatal lines found in?

A

all primary teeth

1st permanent molars

55
Q

The Type I collagen matrix has fibers that run ___ to the basal lamina.

A

parallel

56
Q

Where are the diameter and density of dentin tubules greatest near?

A

the pulpal surface

57
Q

Where are the diameter and density of dentin tubules the smallest?

A

near the DEJ

58
Q

Because of the decreasing ____ of the pulp chamber, the number of dentinal tubules per unit area at the pulpal surface is greater than at the DEJ (which is 1/2 of those at pulp).

A

volume

59
Q

Can odontoblastic processes branch?

A

YES - they branch as they exit DEJ

60
Q

Why do odontoblastic processes branch?

A

to allow the processes to have anchor points so it can grow and stretch without pulling away/separating

61
Q

____ dentin is more mineralized; ____ dentin is demineralized.

A

Peritubular; intertubular

62
Q

_____ dentin is around the tubule, is more mineralized, and is more resistant to etch (“white rings”).

A

Peritubular

63
Q

____ dentin is located between tubules and is more “hairy.”

A

Intertubular

64
Q

____ dentin is mineralized in an organized fashion.

A

Linear

65
Q

_____ dentin is characterized by interglobular spaces that are unmineralized or hypomineralized dentin between islands of normal calcified dentinal layers.

A

Globular (interglobular)

66
Q

Where is globular/interglobular dentin formed?

A

in the crowns of teeth between normal calcified dentinal layers

67
Q

Where specifically is globular dentin mostly found?

A

in the crowns of teeth and in Tome’s granular layer

68
Q

____ is a granular-appearing layer in the dentin of the root adjacent to the cementum, possibly comprised of hypomineralized interglobular dentin.

A

Tome’s Granular Layer

69
Q

Is mantle dentin primary dentin?

A

NO

70
Q

____ is all dentin (except mantle dentin) that is formed up until the time the tooth achieves functional occlusion.

A

Primary dentin

71
Q

____ is all dentin that is formed after the tooth achieves functional occlusion.

A

Secondary dentin

72
Q

What are dentin tubules called that are void of odontoblastic processes?

A

dead tracts

73
Q

What are dead tracts filled with and what do they look like?

A

filled with air or organic debris

looks black in transmitted light microscopy

74
Q

What is dentin called that is occluded with mineral?

A

sclerotic dentin

75
Q

What is sclerotic dentin and what does it look like?

A

occluded with mineral
non-tubular and nearly transparent
looks black in transmitted light microscopy

76
Q

Does the presence of sclerotic dentin increase or decrease with age?

A

INCREASE

77
Q

What is dentin called that’s deposited by newly differentiated odontoblasts at the site of pulpal trauma?

A

reparative dentin (tertiary dentin)

78
Q

What stimulates and forms the matrix of reparative dentin?

A

cells in the subodonoblastic layer, once exposed to growth factors

79
Q

Is all tertiary dentin formation the result of caries?

A

NO - pulp capping initiates reparative dentin formation too

80
Q

What is pulp capping?

A

stimulating a bridge of reparative dentin by using calcium hydroxide to seal off exposed pulp

81
Q

Cells in the subodontoblastic layer, once exposed to growth factors released by stimulated ____, differentiate and form the matrix of reparative dentin.

A

pulpal cells

82
Q

What part of the tooth does tetracycline affect?

A

the part of the tooth that was developing at the time the drug was introduced

83
Q

T/F: Staining from tetracycline only affects the top layer of the tooth.

A

FALSE - tetracycline staining gets deeper as you cut into the tooth

84
Q

How is tetracycline staining treated?

A

bleaching (6-7 months) or veneers

85
Q

T/F: Both dentin and enamel are affected in dentinogenesis imperfecta.

A

FALSE - dentin is affected and enamel is NORMAL

86
Q

What hereditary defect results in normal enamel that chips off easily due to lack of support by abnormal underlying dentin?

A

dentinogenesis imperfecta

87
Q

In dentinogenesis, there is a lack of ____ at the DEJ.

A

tuftelin

88
Q

What hereditary defect results in bluish-gray teeth with an opalescent sheen and obliterated pulp chambers?

A

dentinogenesis imperfecta

89
Q

____ is a loss of tooth structure due to mechanical wear due to bruxism (tooth to tooth contact during mastication or parafunction).

A

Attrition

90
Q

____ results in matching wear facets on occluding surfaces and shiny facets on amalgam contacts.

A

Attrition

91
Q

T/F: Enamel and dentin wear at the same rate.

A

TRUE

92
Q

How can the pulp chamber be exposed in attrition, but not cause debilitating pain?

A

reparative dentin is laid down on top to protect the pulp

93
Q

____ is the loss of hard dental tissue by chemical processes.

A

Erosion

94
Q

____ results in broad concavities, with cupping of occlusal surfaces and dentin exposure.

A

Erosion

95
Q

Do you see wear on non-occluding surfaces with erosion?

A

YES - and incisal translucency

96
Q

Are patients with erosion hypersensitive?

A

YES

97
Q

How would you treat caries that is only present in the enamel?

A

with fluoride

98
Q

How would you treat caries that goes deeper into the enamel?

A

with a sealant

99
Q

How would you treat caries that has entered the dentin?

A

restore

100
Q

How would you treat caries that has entered the pulp?

A

extraction or root canal

101
Q

Caries is a balance between ____ and ____ factors.

A

pathological; protective

102
Q

Acid-producing bacteria, frequent snacking on fermentable carbohydrates, and subnormal saliva flow are all ____ factors.

A

pathological

103
Q

Proper saliva flow and its components, fluoride/calcium/phosphate, and chlorhexidine/iodine/xylitol are all ____ factors.

A

protective

104
Q

Hydroxyapatite crystals exhibit a core of more soluble _____.

A

carbonate apatite

105
Q

Where does carbonate substitution in the lattice structure of enamel primarily occur?

A

phosphate sites

106
Q

What portion of hydroxyapatite crystals are eroded preferentially?

A

core of carbonated apatite

107
Q

Which element substitutes hydroxyl ions in hydroxyapatite crystals, conferring greater stability and resistance to acidic dissolution?

A

fluoride

108
Q

What are the bacteria responsible for dental caries on dentin and enamel surfaces?

A

Streptococcus mutans
Streptococcus sorbrinus
Streptococcus gordonii
Lactobacillus acidophilus

109
Q

What bacteria are responsible for dental caries on roots?

A

Actinomyces viscosus

Candida albicans

110
Q

Caries spread ____ as it reaches the DEJ and progresses into the dentin.

A

laterally

111
Q

Why does the caries process spread laterally at the DEJ?

A

the spread is due to the branching of dentinal tubules (odontoblastic processes) at the DEJ

112
Q

What do caries look like in the enamel? In the dentin? What is the shape?

A

initial caries lesion exhibits small opening in enamel

then, a pyramidal shaped lesion within the dentin with the apex of the pyramid pointing towards the pulp

113
Q

What actually causes the substantial cavitation of advanced caries?

A

the bulk of the decay is beneath the enamel surface, so when caries invades the dentin, there is not enough dentin underneath to support the enamel (so then it chips)

114
Q

What is the cause of a periapical abscess?

A

caries that has progressed into the pulp cavity, where pus forms and causes necrosis in the PDL and alveolar bone

115
Q

How can grooves in teeth be protected from caries?

A

sealants

116
Q

How many adults suffer from dentinal sensitivity?

A

1 in 5 adults

117
Q

What teeth are most commonly affected by sensitivity issues?

A

canines and premolars

118
Q

What are some stimuli for sensitivity?

A 
cold or hot beverages
sweet, sour, or acidic foods
overly aggressive brushing
acidogenic plaque bacteria
cosmetic tooth bleaching
clenching and bruxism
119
Q

What theory of dentinal sensitivity theorizes that sensitivity is caused by direct stimulation of nerve endings in tubules?

A

Direct Innervation Theory (not actually supported though because free nerve endings don’t extend into DEJ)

120
Q

What theory of dentinal sensitivity theorizes that sensitivity is caused by stimulation of odontoblasts that are coupled to nerves in pulp?

A

Transduction Theory

121
Q

What theory of dentinal sensitivity theorizes that sensitivity is caused by movement of tissue fluids within dentinal tubules that stimulate free nerve endings in close association with dentin?

A

Hydrodynamic Theory (most accepted theory)

122
Q

_____ Law states that the volume of a gas or fluid is directly proportional to the amount of heat applied at a constant pressure.

A

Charles’

123
Q

Heat to a sensitive tooth = fluid movement volume ____; Cold to a sensitive tooth = fluid movement volume ____.

A

increased; decreased

Histopathology (7 decks)

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