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Anatomy > Dentin > Flashcards

Dentin Flashcards

1
Q

The dentin supports the ________ and ______.

A

Enamel crown and roots of teeth

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2
Q

Within the dentin is _______.

A

Pulp cavity which is the living part of the tooth (alive cells)

Highly vascularized and innervated.

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3
Q

In enamel, the inner portion of the enamel organ differentiates into ameloblasts. What happens for the dentin precursor?

A

The dental papillae differentiate into odontoblasts.

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4
Q

Mineralization of dentin is similar to ______ and less than _____.

What properties does this give dentin?

A

Bone, Enamel

Elasticity (mechanically supports harder overlying enamel)

Tight Scalloped DEJ

Cementum and DEJ is less distinct

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5
Q

Dentin is made of how much

Inorganic material.
Organic material
Water

A

70% Inorganic (mineralized calcium hydrozyapatite crystals)

20% organic material (Type 1 ,3,4 collagen and non collagenous matrix proteins)

10% Water

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6
Q

What is the ___% organic material of dentin made up of?

A

20%

Type 1 collagen: Forms scaffold for mineral
Type 3 Collagen: First Secreted to make the pre-dentin matrix
Type 4 collagen
Non-Collagenous matrix proteins

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7
Q

What are the 3 types of dentin?

A

Primary
Secondary
Tertiary

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8
Q

What is primary dentin?

A

Circumpulpal - Dentin around pulp cavity
Peritubular
Intertubular
Mantle - DEJ - First dental laid down

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9
Q

What is secondary dentin?

A

Deposited after root formation

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10
Q

What is tertiary dentin?

A

Reparative dentin formed in reaction to caries and dental procedure

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11
Q

What is the first dentin laid down? What is laid second?

A
  1. Mantle dentin (forms DEJ)
  2. Circumpulpal Dentin

These two together make up primary dentin

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12
Q

What is the final dentin added?

A

Secondary layer after root formation that can occur even after tooth is growing since roots are growing them

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13
Q

A majority of dentin is made of _________.

A

Primary Circumpulpal dentin structure with peritubular and intertubular dentin.

There are tubules in circumpulpal dentin that run from the pulp cavity up to the enamel. Within them are odontocyte processes that lead into the pulp where odontocytes live.

Peritubular dentin surrounds these odontocyte process holding tubule

Intertubular dentin fills the space between each peritubular dentin surrounded tubule.

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14
Q

Where do odontocytes live?

A

Along the secondary dentin. They SHOULD NOT be in pulp.

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15
Q

Primary dentin, secondary dentin and tertiary dentin all contain odontocytes/blasts. True or false

A

FALSE

Primary does NOT. It does contain odontoblast processes in its tubules

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16
Q

Peritubular and Intertubular dentin are ________ mineralized.

Where are they located?

A

Highly

Peritubular- Wall of tubule

Intertubular- Between tubules

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17
Q

Primary Dentin is made of ____________ and is formed before completion of the ________.

What it its rate of deposition and mineralization?

A

Circumpulpal Dentin ( Peritubular + Intertubular dentin) + Mantle Dentin (First layer of dentin ever)

Apical foramen

Rapid formation, high mineralization

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18
Q

Secondary dentin is formed after the ____________ and is the ______layer.

What it its rate of deposition and mineralization?

A

completion of apical foramen

final

slow formation, low mineralization

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19
Q

Tertiary dentin is found as a ____________.

What does it look like?

A

result of localized injury to exposed dentin

irregular course of tubules

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20
Q

Tertiary dentin is cellularized. True or false?

A

True

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21
Q

Remember enamel spindles from enamel lecture! Where do they come from?

A

Enamel spindles are actually the distal end of odontoblast processes that are protruding out of the DEJ from the pulp.

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22
Q

Most of the dentin matrix is made of _________.

How are odontoblast processes held together?

A

Intertubular dentin

Canaliculus connecting different odontoblastic processes.

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23
Q

Pre-dentin is secreted at a rate of about ________.

It is mineralized or unmineralized ?

What is it made of?

A

4 micrometers a day

unmineralized

Collage Type I ( Low 3 and 5), dentin phosphoprotein, substratum for mineralization, odontoblasts secrete collagen

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24
Q

What secretes collagen _____ in the predentin?

A

1 (3,5)

Odontoblasts

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25
Q

Non-collagenous Matrix Proteins

KNOW FOR EXAM

A
  1. Dentin Phosphoprotein/phosphophoryn
  2. Dentin sialoprotein
  3. Dentin glycoprotein
  4. Dentin matrix protein
  5. Osteonectin - BONE PROTEIN
  6. Bone sialoprotein - BONE PROTEIN
  7. Osteopontin - BONE PROTEIN

Please Say Grace Made OraNge SorBet pOPsicles

P
S
G
O
BS
OP

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26
Q

Secondary dentin will be closest to the _____.

How fast does it deposit and what is the tubule ratio?

Describe histological image

A

Pulp chamber: Will be abundant at roof of pulp chamber to protect pulp horns

Slow; 1 micrometer a day
Few Tubules

There will be a bending of tubules between primary and secondary dentin. Will stain paler than primary dentin.

27
Q

Tertiary dentin will appear ____________.

A

as sparse and irregular tubules

Forms in response to injury and odontoblasts differentiate at site of injury.

28
Q

What is dentinogenesis and when does it begin?

A

Dentin creation; Bell Stage

29
Q

Dentin precursor is an ___________ which differentiates from ___________ of ___________. They are induced by ____________.

A

odontoblast, ectomesenchymal cells of the dental papilla.

They are induced by pre-secretory ameloblasts of inner enamel epithelium.

30
Q

Dentinogenesis starts at the __________ and later in the _________ driven by ________.

A

Cuspal region (cornonal dentin)

Root (Hertwig’s root sheath)

31
Q

Describe the induction of odontoblasts.

A

Ameloblasts instruct a dental papilla cell to become an odontoblast after breaking down of the basement membrane.

This cell will increase in size and continue to multiply to create more odontoblasts. One of the cells will stay behind in the pulp to serve as a stem cell

32
Q

Hertwigs root sheath ONLY produces dentin. True or false?

A

True; it induces root dentin formation before tooth eruption when the tooth is 2/3rds complete.

33
Q

Deciduous teeth root formation finishes __________.

What about permanent teeth root formation?

A

18 months after eruption

2-3 years after eruption

34
Q

Root development is a later occurring event in dentinogenesis. True or false

A

True

35
Q

Preodontoblast cells are odontoblast precursors. What happens differentiated dental papilla cells have now become odontoblasts?

A
  1. Cells elongate
  2. More cytoplasmic organelles including RER and Golgi Complex
  3. Nucleus is polarized away from IEE(closer to pulp)
  4. Formation of odontoplast process that gets trapped just beyond DEJ
36
Q

Odontoblasts are easy to replace. True or false?

A

FALSE; processes won’t grow back

37
Q

The presecretory odontoblast has now become a secretory odontoblast. What are its characteristics?

A

Taller columnar cells with extensive RER, Golgi and secretory vesicles

Synthesize and elaborate extracellular material

SECRETE TYPE I COLLAGEN and ground substance extracellularly in the same way as fibroblasts

Secrete PRE-dentin.

38
Q

Which collagen is secreted first? What is MOST of the dentin made of?

A

Collagen III

Collagen I

39
Q

How do odontoblastic processes grow?

A

The apical surface of the process will embed in the enamel at the DEJ forming a SPINDLE.

As the dentin gets thicker towards the pulp, odontoblasts are migrating towards the pulp as well thus extending the processes into the dentin within tubules.

40
Q

What is the first sign of dentinogenesis?

A

Type 3 collagen is deposited first and then Type 1.

Dentine matrix vesicles appear, grow and release matrix

THE DEPOSITION OF VON KORFF’S FIBERS - initiates predentin formation via Type III collagen fibers with fibronecting

41
Q

What do Von Korff’s fibers look like?

A

There will be strings emitting from predenting

42
Q

How does dentin calcify?

A

Mineralization tends to occur in small brown discrete areas called calcospherites.

The small regions eventually coalesce to form a globular solid mass of mineralized dentin.

They do not fuse completely we see regions of unified Dentin called Interglobular dentin.

43
Q

Where does dentin calcify?

A

Calcospherites

44
Q

What is uncalcified dentin called?

A

Inter-globular dentin

45
Q

What is a linear calcification? Which dentin does it occur most in?

A

Linear calcification is when mineralization progresses slowly. Calcospheroids are NOT formed here and mineralization is slower.

Occurs more in secondary dentin.

46
Q

Peritubular dentin is ___% _____ mineralized than intertubulular dentin.

A

40% more

47
Q

What is sclerotic dentin?

A

Occurs when dentinal tubules become occluded.

INCREASES WITH AGE

Will look dark due to dead tubules

Can occur due to caries lesions filling with bacteria, demineralized dentin due to increased acidity in mouth

48
Q

What are the incremental lines of growth for dentin called?

A

Von ebner

Every 5 days there is a change in orientation of collagen fibers. Deposition is 4 micrometer every day.

49
Q

What are Contour lines of Owen?

A

Exaggerated incremental lines that reflect changes in nutritional status or disease in the individual during the period of Dentin formation.

BIRTH CORRELATION

50
Q

Pulp is derived from ___________.

A

Mass of dental papilla during the early bell stage.

51
Q

Dental pulp is a ______.

A

Connective tissue

52
Q

There are 4 zones in the pulp.

A
  1. Odontoblast
  2. Partially Cell “free” zone of Weil
    3.Cell Rich Zone
    4.Pulp Core
53
Q

Why is the cell free zone important?

A

There are less cells and more extracellular matrix in order to allow for distribution of nerve fibers in the pulp.

54
Q

Nerve fibers can penetrate ______-

A

dentin tubules

Dentin has sensitivity!

55
Q

Does enamel have nerve involvement?

A

NO

56
Q

What are other cells in the pulp?

A

Fibroblast that make pulp matrix

Undifferentiated ectomesenchymal cells (dental pulp stem cells). They transform into fibroblasts or odontoblasts if needed.

Macrophages
T- Lymphocytes
Dendritic cells (antigen presenting)

57
Q

Why are undifferentiated ectomesenchymal cells important?

A

Undifferentiated cells can transform into fibroblasts or odontoblasts if cell population is reduced after injury.

58
Q

What are dendritic cells?

A

Antigen presenting in PULP

59
Q

What collagen types were seen in pulp?

A

Glycosaminoglycans
Glycoproteins
Water

Collagen 1 and 3

60
Q

What is the specific name for BV in pulp?

A

Fenestrated Capillary Plexi

61
Q

Innervation pattern of pulp

A

Cranial nerves enter through apical foramen of individual teeth and grow as bundles into pulp into the Cell-FREE Zone

When they get to the cell-free zone, they split off and find an odontoblast to track it to the dentin tubule

62
Q

What can cause pain from dentin?

A

Cold air,water
Mechanical contact
Dehydration

63
Q

What happens to pulp as we age?

A

There will be a decrease in volume of chamber due to continue deposition of dentin.

There will be a reduction of vascular supply

Cell density will be reduced with increase of fiber bundles

There will be a loss of axons and pulp sensitivity

Calcification

There will be a reduction in the diameter of the tubules

There could be a complete closure of the tubules by sclerotic dentin

Increased brittleness

Contraction of odontoblastic process, or death of ole blast found near Apex

64
Q

What are pulp stones?

A

Calcification blobs in pulp

Anatomy (16 decks)

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