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I.O.E Dental anatomy and Histology > Periodontium > Flashcards

Periodontium Flashcards

1
Q

After root formation what happened to dental follicle cells?

A

They show an increase in cytoplasmic organelles especially those associated with protein synthesis and secretion

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2
Q

Where are the ground substances found and what do they do?

A

They are found between collagen fibres They are thought to have many important functions including: Water binding Control of collagen fibrillogenesis Fibre orientation Binding of growth factors

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3
Q

What are the 6 cells that make up the PDL?

A
  1. Fibroblasts 2. Cementoblasts 3. Osteoblasts 4. Osteoclasts 5. Epithelial cells (Rests of Malassez) 6. Macrophages
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4
Q

What do the epithelial cell rests of malassez look like?

A

They appear as islands of epithelial cells

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5
Q

What do reticulin fibres form and what do they do?

A

They for crosslinks and a fine meshwork to aid tissue support

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6
Q

What are maacrophages?

A

Defense cells They are blood borne cells that enter the PDL from blood vessels They make up a small percentage of the cell population

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7
Q

What is the gingival cuff?

A

The region of attachment of the gingiva to the tooth

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8
Q

The junctional epithelium is a specialised nonkeratinised stratified squamous epithelium which is unusual in having a ……………..on both surfaces.

The ……………….is ‘deposited on the enamel surface and the cells attach via …………..

A

basal lamina

basal lamina / hemi-desmosomes.

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9
Q

What type of event is the degradation of collagen fibrils in MOST connective tissue?

A

An extracellular event as the cells secrete collagenases into the extracellular environment

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10
Q

What are the 4 main functions of the periodontal ligament?

A
  1. It’s responsible for resisting displacing forces and for protecting the dental tissues form damage caused by excessive occlusal loads 2. Responsible for the mechanisms whereby a tooth attains and maintains its functional position 3. Its cells form, maintain and repair alveolar bone and cementum 4. Its mechanoreceptors are involved in the neurological control of mastication
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11
Q

What is the periodontal ligament?

A

It is the dense fibrous connective tissue that occupies the periodontal space between the cementum of the root and the alveolar bone of the tooth socket

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12
Q

What’s the difference between Sharpeys fibres found in the cementum and bone?

A

Sharpey’s fibres insertions into bone are larger but less numerous than those into cementum.

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13
Q

Where do the oxytalan fibres run in the outer part of the PDL?

A

Runs obliquely down from the cementum to terminate in the vicinity of the periodontal capillaries

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14
Q

Where is the basal lamina deposited?

how do JE cells attach??

A

It is deposited on the enamel surface and the cells attach via the semi-desmosomes

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15
Q

Where do the oxytalan fibres run within the periodontal ligament proper?

A

They tend to be more longitudinally orientated, crossing the oblique fibre bundles more or less perpendicularly

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16
Q

What processes surround the fibre bundles?

A

Cellular processes surround, or envelop, the fibre bundles

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17
Q

The lamina propia of the gingiva is what?

A

A relatively dense and fibrous tissue that has insertions into both tooth and bone of the alveolar crests

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18
Q

Why might the phagocytic process of degrading collagen fibrils in the PDL be more advantageous

A

This may enable the cells to control the degradative process more precisely.

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19
Q

What us the junctional epithelium

A

It is a specialised nonkeratinised stratified squamous epithelium which is unusual in having a basal lamina on both surfaces They are part of the gingival cuff

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20
Q

What is the suggested function of oxytalan fibres?

A

There is no clear idea but the suggested function of these fibres might be to aid fibroblast migration in the PDL

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21
Q

The region of attachment of the gingiva to the tooth is called what?

A

The gingival cuff

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22
Q

What does the PDL demonstrate in response to axial loading?

A

The periodontal ligament demonstrates a BIPHASIC, ‘VISCO-ELASTIC’, response to axial loading

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23
Q

What fibres are involved in tooth support?

A

Collagen fibres, Vasculature Ground substance

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24
Q

When are extrinsic fibres incorporated into the precementum? Give an example of an extrinsic fibre

A

When further mineralisation occurs An eg is Sharpeys fibres

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25
Q

What found between the collagen fibres?

A

The ground substance

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26
Q

extracellular matrix is…………… In thick histological sections the fibrils of collagen are formed into larger bundles termed …………. These are named according to their position and orientation within the ligament. Between the collagen fibrils is the …………composed of ……….., ………….and other minor elements. ……………….is a second fibre type which, as we will see later, appears to be an immature form of elastin.

A

Type I collagen

principle fibers

ground substance

proteoglycans, glycoproteins

Oxytalan

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27
Q

cells of the periodontal ligament are the …………, ………. …………….and …………….

The…………….. are the cells responsible for removing bone. In normal circumstances there is no equivalent cell for …………..

Also found are small ‘islands’ of epithelial cells called the……………….. These are a remnant …….. Like most other connective tissue, ………….may also be seen.

A

fibroblast,cementoblasts, osteoblasts and osteoclasts

osteoclasts

cementum

‘cell rests of Malassez’.

of the development processes of the tooth root

macrophages

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28
Q

What is the difference between the ‘pre-elastin’ and mature elastin?

A

Pre-elastin does not have a central amorphous core

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29
Q

The other fibre type apart from collagen found in the ligament id the so-called …………… When a section of ligament is stained with a stain for elastin, a positive result where the oxytalan fibres are stained purple only arises if the section is first pre-oxidised – hence the name …….. Their orientation is generally to run ……….. down from the ……….to terminate in the vicinity of the ………….. …………… As yet there is no clear idea as to their function

A

oxytalan fibre

‘oxytalan’

obliquely

cementum

periodontal capillaries

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30
Q

What does the lamina propia of the gingiva do?

A

They act together with tissue fluid to support the free gingiva and hold the attached gingiva against the tooth

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31
Q

Which orientation of the principle collagen fibres is the largest?

A

Oblique fibres

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32
Q

What lie close to the surface of newly formed unmineralised dentine?

A

Adjacent cells of the dental follicle come to lie close to the surface of the newly formed unmineralised dentine

33
Q

What does evidence suggest collagen fibres, vasculature and ground substance are involved in?

A

Tooth support

34
Q

How does the PDL seem to resist intrusive loads

A

Some of the load applies to the tooth is probably dissipated through the oblique fibre system Primarily the ligament appears to resist intrusive loads by compression and fluid flow

35
Q

What does their ultrastructural characteristic of oxytalan suggest?

A

Suggests that they are immature elastin fibres called ‘pre-elastin’

36
Q

What is the extracellular matrix made up of?

A

Type I collagen Glycosaminoglycans Proteoglycans Glycoproteins Oxytalan Water

37
Q

What can the epithelial cell rests of Malassez be triggered to do?

A

These cells can be triggered to proliferate and form peri-apical cysts

38
Q

The gingiva is a …………. epithelium adn underlying connectve tissue…………. that surrounds the teeth

A

highly kertinized

Lamina propria

39
Q

What might the elaunin fibres do?

A

They might provide mechanical protection for the vascular system

40
Q

Where are elastin fibres found?

A

Elastin fibres are restricted to the walls of the blood vessels

41
Q

Where do the majority of capillaries within the ligaments have their origin?

A

Their origin is in the intra-bony spaces within the alveolus Arterioles within the gingiva may also be involved

42
Q

What are the fibroblasts responsible for?

A

For the synthesis and degradation of collagen and for secretion of all components of the PDL ground substances

43
Q

The periodontal ligament demonstrates a ………………. response to axial loading

A

biphasic, ‘visco elastic’’

44
Q

Where do the apical fibres run?

A

They radiate from the root to the apex

45
Q

Where are Sharpeys fibres found in abundance?

A

The aceullular cementum

46
Q

Where do the alveolar crest fibres run?

A

They run from the alveolar crest upwards to insert into the cementum below the crown

47
Q

What is the PDL made up of?

A

Connective tissue (mainly fibroblasts) and an extracellular matrix

48
Q

What is an unusual feature of periodontal fibroblasts?

A

They frequently contain intracellular vacuoles containing fragments of fibrillar collagen

49
Q

What do cells of the inner layer of the dental follicle differentiate to?

A

Cementoblasts that form the initial layer of cells on the surface of root dentine

50
Q

Non calified part of the gingiva is…………. and ……………

the boundary between the two is a

The calicfied part of the periodontium is…… and …………

A

periodontal ligament and lamina propria

horizontal line drawn at the boundary of the avelor crest

alvelor bone and cementum

51
Q

What are the epithelial cell rests of Malassez?

A

Remnants of the epithelial root sheath of Hertwig which disintegrates following root development and have been considered to be relatively inactive

52
Q

Where do the horizontal fibres run?

A

Run horizontally from bone to tooth

53
Q

What is the PDL derived from?

A

Derived from the dental follicle

54
Q

What do fibroblasts secrete into the PDL?

A

Collagen

55
Q

What are the 5 different orientation of the principle collagen fibres?

A
  1. Dentoalveolar crest fibres 2. Horizontal fibres 3. Oblique fibres 4. Apical fibres 5. Inter-radicular fibres
56
Q

What happens to dental follicle cells once cementogenesis has begun?

A

The remaining cells of the dental follicle become obliquely orientates along the root surface and show an increased content of intracellular organelles They become fibroblasts

57
Q

By what process does the degradation of collagen fibrils occur in the periodontal ligament?

A

The fibroblasts appear to degrade the fibrillar collagen by phagocytic process

58
Q

Which cell makes up most of the PDL

A

Fibroblasts

59
Q

What are the collagen fibres in the extracellular mastic gathered into?

A

They are gathered to form bundles called principal fibres

60
Q

There are five principle fibre

running from the alveolar crest upwards to insert in the cementum just below the crown.

run horizontally from bone to tooth.

the largest group and are termed .

The fibres which radiate from the root apex,

In a multi-rooted tooth the fibres which radiate from the apex of the interradicular bone (i.e. the bone between the roots)

A

alveolar crest fibres,

horizontal fibres

oblique fibres

apical fibres

inter-radicular fibres

61
Q

What process triggered the formation of fibroblasts?

A

Cementogenesis

62
Q

Where does the PDL get its blood supply from?

A

The PDL has a rich blood supply derived from the superior or inferior alveolar arteries

63
Q

Where do the Inter-radicular fibres?

A

In a multi rooted tooth the fibres radiate from the apex of the inter-radicular bone

64
Q

Which cells are of mesenchymal origin?

A

Cementoblasts Osteoblasts Preosteoblasts Precementoblasts Epithelial cells

65
Q

The lamina propria of the gingiva is a relatively ………………………………………that has insertions into both ……………and ………………..

This region of attachment of the gingiva to the tooth is often called the

Also part of the gingival cuff (but not strictly speaking part of the periodontium) is the

A

dense and fibrous connective tissue

tooth

bone of the alveolar crest.

‘gingival cuff’.

junctional epithelium.

66
Q

What do the capillaries and arterioles in the PDL form around the tooth?

A

They form a PLEXUS around the tooth which is primarily situated towards the socket wall, between the principal fibre bundles Occupies 50% of the periodontal space

67
Q

What is the basic unit of collagen fibres?

A

Triple helical tropocollagen molecules

68
Q

the failure stress and strain of the periodontal oblique fibers are more akin to …………. than either adult tendon or skin

A

foetal tendon

69
Q

Explain the phagocytic process of degrading collagen fibrils

A

Lysosomes fuse with the ‘phogosome’ containing the collagen fibril and form a ‘phago-lysosome’ where the fibril is degraded. .

70
Q

What type of cell and where are cementoblasts and osteoblasts found?

A

They are formative cells found on the surface of both the cementum and alveolar bone

71
Q

Where are elaunin fibres found?

A

They are found around the blood vessels

72
Q

Which organelles to fibroblasts have a lot of?

A

They are metabolically active with large amounts of rough endoplasmic reticulum

73
Q

What do the cells of the dental follicle differentiate to form?

A

Cementoblasts Fibroblasts Osteoblasts

74
Q

How is the PDL formed?

A
  1. Once the crown has fully formed the internal and external enamel epithelia proliferate downwards as a double layer sheet of flattened epithelial cells, epithelial root sheath of Hertwig that outlines the shape of the tooth 2. Then the epithelial root sheath induces the peripheral cells of the dental papillae to differentiate into odontoblasts and begin producing dentine 3. It’s in contact with the initial pre-dentine layer for only a short time before the continuity of its cell is lost
75
Q

What characteristics do dental follicle cells have prior to root formation?

A

They have the characteristics of undifferentiated mesenchymal cells

76
Q

What happens when triple helical tropocollagen molecules are secreted outside the cell?

A

They are cleaved and spontaneously aggregate in a staggered fashion, first as a 5 membered micro fibrils and then into classical fibrils

77
Q

What do the unmineralised fibres of the PDL run into?

A

They run into the organic matrix of precementum secreted by cementoblasts

78
Q

the ligament tends to resist intrusive loads primary by …….. and ………..

A

compression / fluid flow

79
Q

What are processes from adjacent cells joined by?

A

They are joined by intercellular contacts to form a cellular network

I.O.E Dental anatomy and Histology (7 decks)

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