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EXAM 2 - Anatomical Sciences > Tooth Development > Flashcards

Tooth Development Flashcards

1
Q

When is the induction stage?

A

6th to 7th week

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2
Q

Ectoderm lining ___ gives rise to oral epithelium and then to _______ (induction)

A

Stomodeum , dental lamina

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3
Q

What is the oral epithelium adjacent to?
Where is structure derived from ?
What separates these tissue types?

A

Deeper ectomesenchyme
Neural crest cells
Basement membrane

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4
Q

What happens during the bud stage?
What time period is this?

A

Proliferation : dental lamina grows into a bud shape that penetrates growing ectomesenchyme
8th week

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5
Q

What happens at the Cap stage?
When does it take place?

A

Proliferation / differentiation / morphogenesis: formation of tooth germ as enamel organ (EO) forms into a cap shape that surrounds inside mass of dental papilla (DP), with an outside mass of dental sac (DS) (both from ectomesenchyme)
9th-10th week

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6
Q

What happens at the bell stage?
When does it take place?

A

Proliferation/ differentiation/morphogenesis: differentiation of enamel organ into bell shape with 4 cell types and dental papilla into 2 cell types
11th -12th week

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7
Q

What happens at the apposition stage?
What step is this?

A

Induction/ proliferation: dental tissue types secreted in successive layers as matrix
Stage 4

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8
Q

What happens at the maturation stage?
What step is this?

A

Maturation: dental tissue types fully mineralize to mature form
Stage 5

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9
Q

Where does the enamel derive from?
What is the tissue source/type?
What are the formative cells?

A

Enamel organ
Epithelium
Ameloblasts

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10
Q

Where does the dentin derive from?
What is the tissue source/type?
What are the formative cells

A

Dental papilla
CT/ ectomesenchyme
Odontoblasts

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11
Q

Where does the cementum derive from?
What is the tissue source/type?
What are the formative cells

A

Dental sac
CT/ ectomesenchyme
Cementoblasts

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12
Q

Where does the alveolar process derive from?
What is the tissue source/type?
What are the formative cells

A

Dental sac
CT/ ectomesenchyme
Osteoblasts

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13
Q

Which dental hard tissue(s) have arrest and reversal lines as their incremental lines?

A

Cementum & alveolar process

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14
Q

What are the incremental lines for enamel?

A

Lines of Retzius

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15
Q

What are the incremental lines for dentin?

A

Imbrication lines of von Ebner

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16
Q

What mature cells are related to enamel?

A

None, lost within reduced enamel epithelium with eruption

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17
Q

What mature cells are related to dentin?

A

None within, only dentinal tubules with processes found instead in pulp

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18
Q

What mature cells are related to cementum?

A

Cementocytes

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19
Q

What mature cells are related to alveolar process?

A

Osteocytes

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20
Q

What resorptive cells are related to enamel?

A

None per se; cells secrete proteinases

21
Q

What resorptive cells are related to dentin?

A

Odontoclasts

22
Q

What resorptive cells are related to cementum?

A

Odontoclasts or cementoclasts

23
Q

What resorptive cells are related to alveolar process?

A

Osteoclasts

24
Q

What is the chemical makeup of enamel? (%)

A

96% inorganic material
1% organic
3% water

25
Q

What is the chemical makeup of dentin? (%)

A

70 % inorganic
20% organic
10% water

26
Q

What is the chemical makeup of cementum? (%)

A

65% inorganic
23% organic
12% water

27
Q

What is the chemical makeup of alveolar process? (%)

A

60% inorganic
25% organic
15% water

28
Q

In which dental hard tissues is regeneration after eruption possible?
Not possible? What happens instead?

A

Dentin, cementum, alveolar process
Not possible in enamel - only remineralization

29
Q

Which dental hard tissues have vascularity?
Innervation?

A

Vasculature: alveolar process
Innervation: possible in dentin (within dentinal tubule), alveolar process

30
Q

What is the basic principle of induction?

A

Process where one tissue directs the development of an adjacent tissue
Mediated by cell contact or factors released by inducing tissue
Can be serial and reciprocal

31
Q

What does the primary epithelial band give rise to?

A

Dental lamina (tooth)
Vestibular lamina (between cheek and teeth)

32
Q

When is the primary epithelial band present?

A

37 days

33
Q

The epithelial band is the result of _____ and change of __________

A

Mitosis, orientation of mitotic cells

34
Q

What structure can be useful in determining that we are looking at the mandibular arch?

A

Meckel’s cartilage

35
Q

Meckel’s cartilage is part of the ________ and gives rise to parts of the _____ and ______

A

Ectomesenchyme
Inner ear , mental portion of the mandible

36
Q

Early on ______ directs the development of the tooth

A

Epithelium

37
Q

What is the tooth/dental placode?

A

Sites of tooth development

38
Q

When are tooth buds present ? In what structure are they present?

A

Weeks 6-8
Dental lamina

39
Q

______ derived ____ regulates gene expression in ectomesenchyme

A

Ectoderm , FGF-8

40
Q

Where is FGF-8 expressed? When?
What does it induce in very early development ?

A

First arch ectoderm at the right place and time
Lhx-6 and Lhx-7 (in ectomesenchyme)

41
Q

How is the positioning of the teeth determined?

A

Expression of PAX9 transcription factor in ectomesenchymal cells DIFFERENTIATES them into dental ectomesenchymal cells

42
Q

What does dental placode formation require?

A

Transcription factor p63 (mitosis)
TNF (apoptosis, cell division )
Ectodysplasin (transmem protein that can be cleaved by fur in to produce a secreted form, involved in morphogenesis)

43
Q

What does a loss of ectodysplasin cause?

A

Fewer teeth

44
Q

What does the over activation of ectodysplasin cause?

A

Extra teeth

45
Q

Once ectomesenchyme has been under the control of the _____ in early tooth development it is now competent to ______ from ______

A

Epithelium
Drive tooth formation, skin epithelium

46
Q

What takes over tooth development after the ectomesenchyme?

A

Neural crest

47
Q

What happens in regions where BMP4 is expressed during development?

A

BMP4 blocks FGF8 from signaling PAX9; no tooth development in this area because extomesenchymal not differentiating into dental ectomesenchyme

48
Q

what role does SHH play in tooth development?

A

important in early formation of bud from dental lamina
Less Shh = less invagination

EXAM 2 - Anatomical Sciences (4 decks)

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