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Oral Histology > Ex 1- Dentin + Dentinogenesis > Flashcards

Ex 1- Dentin + Dentinogenesis Flashcards

1
Q

______ is a soft connective tissue in the tooth center. Contains blood vessels and whole cells. Non-mineralized

A

pulp

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2
Q

______ is the mineralized connective tissue covering pulp. Contains NO blood vessels or whole cells bud does contain odontoblast processes and nerve endings

A

Dentin

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3
Q

What are the clinical significance of dentin?

A
  • Quantitative

- Protective- both pulp + enamel

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4
Q

Compared to enamel dentin has a _________ compression strength

A

higher

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5
Q

_______ cushions the overlying more brittle ______

A

dentin

enamel

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6
Q

_______ is scalloped in the crown and facilitates adhesion

A

DEJ

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7
Q

Dentinogenesis beings during the _____ Stage

A

Bell

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8
Q

What occurs just prior to dentinogenesis?

A
  • Tissue layers of dental organ present
  • crown outline present
  • no odontoblasts or ameloblasts
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9
Q

During the ______ Bell Stage inner enamel epithelial cells contain ameloblasts, undifferentiated mesenchymal cells (dental papilla) contains odontoblasts, dentin an enamel secreted

A

Late

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10
Q

Dentinogensis from _____ _____ to cervix and from periphery to ______ ______

A

cusp tip

pulp center

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11
Q

What part of tooth germ does dentinogenesis begin?

A

most coronal portion

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12
Q

Inductive signals for odontoblast differention is secreted from the _____ ______ most likely from cells of the ______ ______

A

enamel organ

enamel knot

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13
Q

______ is one molecule implicated in inducing odontoblast differentiation and expression immediately _______ the wave of odontoblast differentiation

A

Wnt 10a

precedes

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14
Q

Wnt 10a is 1st expressed in the enamel knot then in preodonotblasts in the cusp tip and then in more ______ parts of the tooth

A

cervical

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15
Q

Wnt 10a induces _______ a molecule expressed by mature odontoblasts

A

DSPP

dentin sialophosphoprotein

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16
Q

Odontoblasts secrete _____ _____ then the matrix is mineralized in progressive stages

A

organic matrix

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17
Q

_____ is unmineralized organic matrix of dentin

A

predentin

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18
Q

What are the 2 requirements for mineralization?

A
  • Ca2+ & phosphate

- initiation of crystal formation

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19
Q

_____ required for mineralization comes from (free ions) in plasma

A

Ca2+

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20
Q

_______ required for mineralization comes from plasma + cleavage of organic molecules containing phosphate in odontoblast by alkaline phosphataste

A

Phosphate

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21
Q

Ca2+ and phosphate are transported into predentin through and btw __________

A

odontoblasts

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22
Q

By itself presence of requisite ions is not sufficient. It requires special mechanisms for the initiation of _______ formation

A

crystal

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23
Q

What are the 2 mechanisms associated with the 2 stages of dentin formation?

A

Mantle (initial)

Circumpulpal (subsequent)

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24
Q

_____ _____ is the initial layer of dentin (ultimately the DEJ)

A

Mantle Dentin

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25
Q

The principal component of the organic matrix of mantle dentin is ______ _______ ____which is secreted by _____

A

collagen type I

odontoblasts

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26
Q

The collagen of the mantle has relatively ______ fibrils oriented at ____ angles to basal lamina/future DEJ

A

large

right

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27
Q

Mineralization by ______ _____ membrane bound veiscles, synthesized by OBD, concentrate Ca 2+, PO-containing & other organic molecules

A

matrix vesicles

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28
Q

During mantle dentin formation; _____ secrete matrix then matrix mineralizes, ________ grow, process elongates (barrier btw dentin + pulp), ________ migrate toward pulp center ________ forms around process

A

odontoblasts
odonotblasts
odontoblasts
dentin

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29
Q

Near the end of mantle dentin formation, one process becomes more ________

A

dominant

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30
Q

_________ dentin is interior to mantle dentin, thicker, overall process is very similar; organic matrix secreted, then mineralized

A

Circumpulpal

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31
Q

Circumpulpal dentin contains collagen type I secreted by ________ cell bodies, ______ fibrils that are ______ to the basal lamina

A

odontoblast
smaller
parallel

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32
Q

Circumpulpal dentin is mineralized by _______ not matrix vesicles

A

proteins

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33
Q

Circumpalpal dentin proteins are synthesized and secreted from the ______ process and bind to collagene

A

odontoblast

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34
Q

Special properties of proteins precipitate Ca 2+ ions preen in interstitial fluid and initiate _______ formation which is known as _______ nucleation

A

crystal

heterogeneous

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35
Q

Mantle dentin is ______ organic and ______ mineralized than circumpulpal dentin and the DEJ is vulnerable to caries in _____

A

more
less
both

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36
Q

Phosphophoryn/Dentin phosphoprotein is relatively specific to ________

A

dentin

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37
Q

____ is the prominent dentinal protein (>50% NCPs- non-collagenous proteins)

A

Phosphophoryn/Dentin phosphoprotein

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38
Q

Phosphoryn/dentin phosphoprotein is highly phosphorylated, high in serine/aspartic acid and is _______/______ which helps pull calcium out of solution to precipitates Ca 2+ ions and initiate mineralization

A

acidic/anionic

39
Q

Dentin by WEIGHT is ___% Inorganic ____% organic and _____% H2O

A

70
20
10

40
Q

Dentin by VOLUME is ___% inorganic ____% organic and _____ water

A

45
33
22

41
Q

Dentin is _____ than bone & cementum but ______ than enamel

A

harder

softer

42
Q

The hydroxyapatite (inorganic) content of dental hard tissues is _____% in enamel, _____% in dentin, _____ - ____% in bone, ____-___ in cementum

A

96
70
50-60
45-50

43
Q

In the mineral phase of dentin hydroxyapatite crystals is 4-5% ______ which is susceptible to demineralization, there are 1000’s of unit cells/crystal, smaller than enamel crystals and in a ______ orientation

A 
carbonate
random (less organized)
44
Q

The extracellular matrix of the organic phase of dentin is _______ and ____-______ proteins

A

collagen

non-collageneous proteins

45
Q

The extracellular matrix is made up of type ___ collagen and is ____% of the organic matrix

A

I

90

46
Q

What are the non-tissue specific proteins that make up the organic phase of dentin?

A

Proteoglycans

Signaling molecules/growth factors

47
Q

The _______ ________ can stimulate cells to make new dentin when demineralization occurs

A

signaling molecules (growth factors)

48
Q

What are the mineralized tissue specific proteins that make up the organic phase of dentin

A

osteocalcin

bone sialoprotein

49
Q

What are the dentin-dominant proteins that make up the organic phase of dentin?

A

dentin matrix protein I
dentin glycoprotein
dentin sialoprotein

50
Q

______ ________ (_____) is >50% NCPs, Anionic, includes long chain of ______ amino acid repeats, >200 serine-serine-aspartic acid, serines are phosphorylated

A
  • Dentin phsophoprotein (DPP, phosphophoryn)

- polar

51
Q

DSPP is the gene for ____, DSP, and DGP

A

DPP

52
Q

_____ ________ is a human hereditary disorder where dentin forms improperly and is associated with mutations in DSPP

A

Dentinogenesis Imperfecta (DI)

53
Q

What are the 2 mutations that cause dentinogenesis imperfecta in humans?

A
  • changes in 1st 3 amino acids (iso,pro,val) critical for trafficking (moving) DSPP through rER
  • small base pair deletions that produce frameshifts coding the part of DPP that contain polar AA repeats: polar change to uncharged
54
Q

When DSPP is mutated it becomes abnormal and cannot be released from _______ it becomes stuck in the _____ or _____ ______

A

odontoblasts
rER
cell membrane

55
Q

Mutated DSPP traps the _____ protein made by the unaffected chromosome thus DI mutation is a _______ _______ mutation

A

normal

dominant negative

56
Q

More DSPP mutants results in ____ DSPP secreted

A

less

57
Q

What re the contents of dentinal tubules?

A
  • fluid (major component = H2O)
  • nerve fibers
  • odontoblastic process
  • collagen fibers
  • non-cellular lining sheath
58
Q

Dentinal tubules are at ______ angles to the DEJ, _____ shaped in crown, ______ in root and have _____ and _____ branches

A

right
S
straight
terminal and lateral

59
Q

Branches are more prominent at the ____ and ____ because mantle dentin has multiple processes

A

DEJ

CEJ

60
Q

The # and diameter of tubules in inner dentin is _____ than outer dentin

A

greater

61
Q

The # and dimensions of tubules vary as a function of distance from ____

A

pulp

62
Q

Tubules occupy much _____ surface area at DEJ than at P-D border

A

less

63
Q

Permeability and wetness ______ toward P-D border

A

increase

64
Q

_______ create a natural pathway for microorganisms

A

Tubules

65
Q

______ dentin is unmineralized dentin

A

Predentin (PD)

66
Q

Dentin is classified according to _____ and under what _____ dentin was formed

A

when

conditions

67
Q

_____ dentin is formed until completion of root development and comprises _____ of dentin

A

Primary

most

68
Q

The 2 types of dentin are ______ dentin that is 20u-150u layer at the DEJ and is _____ mineralized. ______ dentin that is central to the mantle and ______ mineralized

A

Mantle
less
Circumpulpal
more

69
Q

______ dentin is formed after root development. Formed at a slower rate but _____ life

A

Secondary

Throughout life

70
Q

Secondary dentin is _____ to primary dentin with a similar structure

A

central

71
Q

Secondary dentin is present along the entire circumference of the _____ chamber but is heaviest on the ____ and ____

A

pulp
roof
floor

72
Q

Secondary dentin is also classified as _______ dentin

A

circumpulpal

73
Q

Secondary dentin is formed throughout life so the pulp chamber gets ______ with aging

A

smaller

74
Q

_______ dentin is produced in specific locations in response to ________ stimulus

A

Tertiary (reparative + reactive)

noxious

75
Q

Tertiary dentin is structurally _______ that may or may not contain _______ and may include cells

A

irregular

tubules

76
Q

Intertubular and intratubular dentin is found in ________ and ______ dentin

A

primary and secondary

77
Q

Intertubular dentin is found _______ tubules and intratubular dentin is found ______ tubules

A

between

lining

78
Q

_______ dentin has a greater volume (intertubular, intratubular)

A

intertubular

79
Q

________ dentin has greater mineralization (intertubular, intratubular)

A

Intratubular

80
Q

_______ dentin is a “ring” wider near DEJ and accounts fro the narrowing of a tubule

A

Intratubular

81
Q

____ dentin is formed away from the pulp

A

Intratubular

82
Q

______ or ___ dentin is formed when tubules are completely filled with intra/peritubular dentin

A

Translucent or sclerotic

83
Q

________ dentin is a normal process of aging

A

Translucent

84
Q

______ dentin is accelerated deposition due to caries or attrition

A

Sclerotic

85
Q

Translucent/Sclerotic dentin _____ with age and makes the tooth harder and more resistant to caries

A

increases

86
Q

______ _____ are formed when tubules dry out and become filled w/ air

A

Dead tracts

87
Q

______ dentin is hypomineralized dentin just below mantle dentin

A

Interglobular

88
Q

The initial mineralization of dentin occurs in _______ foci, individual foci calcify forming ____ that fuse

A

discrete

calcospherites

89
Q

______ dentin forms when individual calcospherites do not fuse

A

interglobular

90
Q

______ ______ layer is prominent in the crown

A

Tome’s granular

91
Q

Intergobular dentin is priminent in ______

A

DSPP knockout mice

92
Q

______ ____ in dentin reflect the incremental pattern of deposition.

A

Growth lines

93
Q

Pronounced growth lines can occur that reflect ______ ie neonatal line

A

perturbations

94
Q

Growth lines can be exaggerated due to _______ treatment

A

tetracycline

Oral Histology (16 decks)

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