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histo 2 > foster #1 > Flashcards

foster #1 Flashcards

1
Q

What are the four components of the periodontium?

A

cementum
alveolar bone
PDL
gingiva

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2
Q

What is the HERS composed of?

A

extension of enamel organ

bilayer of outer, inner epithelium

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3
Q

What does the HERS do?

A

defines root size and shape

induces root odontoblast differentiation

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4
Q

How does HERS use epithelial-mesenchyme signaling?

A

HERS induces dental papilla cells to become odontoblasts

root dentin forms yada yada

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5
Q

What happens to the HERS?

A

mostly disintegrates

some cells become epithelial rests of malassez

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6
Q

Is root dentin continuous with crown dentin?

A

yes

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7
Q

How does dentinogeneis of root dentin differ from crown?

A

it is interacting with HERS instead of inner epithelial enamel

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8
Q

What happens when Nfic is missing?

A

dental papilla cannot respond to HERS signaling (so no odontoblast differentiation)

rootless tooth

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9
Q

dilaceration

A

deformity in shape/direction

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10
Q

taurdontism

A

large pulp chamber at expense of root/furcation

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11
Q

What are the two major types of cementum? Location?

A

primary acellular cementum - cervical 2/3 of root

secondary cellular cementum - apical 1/3

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12
Q

Where would you find cellular mixed stratified cementum?

A

in the middle region of the root where cellular and acellular overlap

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13
Q

What are the special functions of cementum?

A

attachment
protection root from absorption
adjusting tooth position
sealing dentin tubules

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14
Q

Does primary acellular cementum have mostly extrinsic or intrinsic fibers? what about secondary?

A

primary = acellular extrinsic fiber cementum (AEFC)

secondary = cellular intrinsic fiber cementum (CIFC)

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15
Q

What is the composition of cementum?

A

50% inorganic

35% organic (mostly type I collagen)

15% water

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16
Q

How is cementum different from bone?

A

avascular
non-innervated
no turnover (appositional growth only)

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17
Q

What is the classic hypothesis for cementum origin?

A

ectomesenchyme > dental follicle > cementoblast

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18
Q

Where do the cells of the PDL originate? What are these cells?

A

dental follicle (ectomesenchyme origin)

cementoblast, fibroblast, osteoblast

fate of cells depends on where they are located

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19
Q

What are the 10 steps of cementogenesis

A
  1. root dentin (platform for cementum)
  2. HERS disintegrates (root dentin exposed)
  3. cementoblast differentiation (from follicle)
  4. initial collagen fibers
  5. PDL fibroblasts (collagen fiber bundles stitched to initial)
  6. Extrinsic fibers (fiber fringe starting to form)
  7. Mineralization of fibers
  8. Secondary cementoblasts (produce cementoid rapidly)
  9. Mineralization of cementoid matrix
  10. Cementocytes
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20
Q

Are the initial collagen fibers in cementogenesis intrinsic or extrinsic?

A

intrinsic

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21
Q

What is the function of cementoblasts? Products?

A

make acellular and cellular cementum

collagens, ECM proteins, enzymes to promote mineralization

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22
Q

What is the fate of cementoblasts?

A

remain in PDL close to cementum surface, regulate slow growth through life, direct repair

23
Q

Is the DCJ harder or softer than the surrounding tissues?

A

softer – acts as a buffer

24
Q

What are sharpey’s fibers and where are they located?

A

insert into the acellular cementum and alveolar bone

dense, highly organized mineralized collagen fiber bundles providing anchorage for tooth-PDL-bone

25
Q

What is the mechanism of acellular cementum mineralization?

A

fiber fringe at the acellular cementum-PDL interface is unmineralized but gets mineralized as time goes on? not very clear

26
Q

summary of acellular cementum development

A
  1. root dentin forms, HERS breaks up
  2. cementoblasts have access to dentin, secrete intermingling intrinsic collagen fibers at CDJ
  3. fiber fringe of collagen fibers develops
  4. PDL fibroblasts extend fiber
  5. cementoblasts mineralize fibers
27
Q

How do cementoblasts make and mineralize cementum?

A

Collagen scaffold is present

cells secrete ECM proteins that promote mineral precipitation (like bone sialoprotein)

cells express proteins that clear mineralization inhibitors (like tissue nonspecific alkaline phosphatase, TNAP)

28
Q

BSP (bone sialoprotein)

A

promotes mineralization

29
Q

TNAP (tissue non specific alkaline phosphatase)

A

clears inhibitors of mineralization (aka promotes mineralization)

30
Q

What would happen if you had a mutation in ALPL?

A

TNAP gets fucked up

hypophosphatasia (HPP) - no acellular cementum

31
Q

What is cementoid?

A

unmineralized cementum (like pre dentin)

32
Q

Is cementoid associated with acellular or cellular cementum?

A

cellular

33
Q

Which type of cementum maintains tooth in proper occlusal position?

A

cellular cementum

34
Q

What type of cementum can repair resorption?

A

cellular cementum

35
Q

How are cementocytes connected?

A

to each other and to the PDL through canaluculi

36
Q

What happens if you remove an opposing tooth?

A

the tooth that remains wants to keep erupting

cellular cementum keeps getting laid down at apex

37
Q

Do both acellular and cellular cementum continue to grow through life?

A

yes – only apposition growth (NO turnover)

38
Q

What happens if you have too much cementum?

A

may lead to ankylosis

39
Q

What happens if you lose cementum?

A

root resorption by osteoclasts

40
Q

How is cementum repaired?

A

reparative cementum fills resorption pit (Howship’s lacuna)

reparative cementum usually cellular, regardless of location

new cementum may not be bonded well to dentin, PDL

41
Q

What type of bone lines the tooth socket? What does it include?

A

bundle bone

includes extrinsic collagen fibers, mineralized sharpey’s fibers

42
Q

Are primary fibers entering bundle bone larger/smaller and less/more dense vs. cementum?

A

larger in diameter, less dense compared to cementum

43
Q

What is the lamina dura?

A

radiopaque layer lining socket

less trabecular than surrounding bone

44
Q

What are some normal functions of bone resorption?

A

normal remodeling (alveolar remodels fastest)
bone resorption for tooth eruption
tooth resorption when baby teeth fall out

45
Q

What is the name for the tooth joint?

A

gomphosis joint

46
Q

What is the normal width of the PDL?

A

0.1-0.25 mm

47
Q

What is the composition of the PDL?

A

ground substance (proteins, proteoglycans, water)

collagen fibers (I, III, XII) 97% of fibers

oxytalan fibers (small elastic, support blood vessels) 3%

48
Q

What are the six groups of PDL collagen bundles?

A 
transeptal 
alveolar crest
horizontal
oblique
apical
interradicular
49
Q

What are the majority of cells in the PDL?

A

fibroblasts

also has cementoblasts, osteoblasts, osteoclasts, epithelial rests, stem cells, immune cells

50
Q

How is the PDL vascularized?

A

perforating cells through alveolar bone (MAJOR)
apical routes
gingival vessels

51
Q

What is the gingival crevicular fluid?

A

fluid found in gingival sulcus, comes from vasculature, may be used in diagnosis of local/systemic problems

52
Q

What cranial nerve innervates all PDL?

A

CN V

53
Q

What are the four nerve endings of PDL and what type of receptors?

A
  1. free endings - most common, nociceptors and mechano
  2. ruffini endings - found near apex, mechanoreceptors
  3. coiled endings - function unknown
  4. encapsulated endings - function unknown
54
Q

What are the four gingival ligament groups?

A
  1. circular
  2. dentogingival
  3. dentoperiosteal
  4. alveologingival

histo 2 (8 decks)

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