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Endemic Oral disease > PAP2- the periodontium anatomy and function > Flashcards

PAP2- the periodontium anatomy and function Flashcards

1
Q

what makes up the periodontal ligament?

A
  • Principal Fibres (collagen/fibroblasts/ ground substances)
  • Loose Connective Tissue •Blast & Clast cells
  • Oxytalan Fibres
  • Cell Rests of Malassez
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2
Q

what does the periodontal ligament attach?

A

Attachment of cementum (root) to the bone :

-sharpey fibres

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3
Q

Name the groups of fibres that make up the periodontal ligament.

A

-Oblique fibres
-Apical fibres
-Horizontal fibres
-Alveolar crest
-Inter-radicular
(look at diagram for direction)

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4
Q

where are inter-radicular fibres found?

A

furcation area

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5
Q

what are the most common types of collagen in periodontal ligament?

A
  • Type I
  • Type III
  • Type V
  • Small amounts of Type IV in basement membranes of blood vessels
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6
Q

what is the difference between type III and type I ?

A

Type III collagen is more fibrillar and extensible than type I collagen
(this property important for accommodating tooth movement )

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7
Q

what is collagen turned over by?

A

Fibroblast cells:

  • formation
  • Broken down
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8
Q

what is the rate of collagen turnover?

A

-Very high rate

half life approx 3 days around the apex

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9
Q

what is found in the loose connective tissue of the periodontal ligament?

A 
•Fibres
•Extracellular matrix
•Cells:
>fibroblast
>undifferentiated mesenchymal cells
>defence cells 
•Nerves
•Vessels:
>blood
>lymphatic
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10
Q

what is the extracellular matrix of the periodontal ligament similar to?

A

gingival tissue matrix

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11
Q

what is the extracellular matrix turned over by?

A

Fibroblasts

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12
Q

what does the extracellular matrix include?

A
  • Hyaluronic acid
  • heparin sulphate
  • chondroitin 4-6 sulphates
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13
Q

what is the extracellular matrix important for binding?

A

Important for binding H2O:
>hydrostatic cushion
>helps to withstand force of mastication

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14
Q

what is the autonomic nerve supply of the periodontal ligament?

A

-Sympathetic :
>C fibres (unmyelinated)
>Vasoconstrictor

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15
Q

what is the primary afferent (sensory) supply of the periodontal ligament?

A
  • Mechanoreceptors (AB fibres -large myelinated)

- Nociceptors ( C fibres -unmyelinated and Ad fibres -small myelinated)

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16
Q

Why is a rich nerve supply to the periodontal ligament important?

A

Important for monitoring masticatory loading + reflex salivation during chewing

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17
Q

What are the 3 principal sources of blood vessels in the heavy anastomosis in the periodontal ligament?

A

-Apical vessels :
>from the vessels that supply the pulp
>run occlusal vertical direction

-Perforating vessels/ lamina dura origin :
>perforating socket wall (cribriform plate)

-Gingival vessels :
>from gingival tissue

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18
Q

what do the lymphatic vessels tend to follow?

A

the venous supply

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19
Q

why is the a rich blood supply to the periodontal ligament?

A

cells are very active and require a kot of energy to be brought to the tooth but they also produce a lot of toxins that must be carried away

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20
Q

what are blasts cells?

A
  • Derived from adjacent undifferentiated connective tissue cells
  • producing cells
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21
Q

what do cementoblasts do?

A
  • line the surface cementum

- lay down cementum

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22
Q

What do osteoblasts do?

A
  • line the end-steal and periosteal alveolar bone surfaces

- lay down bone

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23
Q

what are clast cells?

A

-derived from bone marrow cells
-remove tissue :
>multinucleate cells
>appear on resorbing surfaces

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24
Q

what do cementoclasts do?

A
  • line the surface cementum

- breakdown cementum

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25
Q

what do osteoclasts do?

A
  • line the end-steal and periosteal alveolar bone surfaces

- breakdown bone

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26
Q

what fibres are unique to the PDL?

A

oxytalan fibres

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27
Q

what is oxytalan fibres nature?

A

-Elastic in nature :
>variant of elastic fibres
>Immature elastin

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28
Q

where do oxytalan fibres insert?

A

into cementum

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29
Q

in what 2 directions do oxytalan fibres run?

A
  • parallel to root surface

- oblique to root surface (across oblique principal fibres)

30
Q

what is the function of oxytalan fibres?

A
  • thought to maintain latency of blood vessels during occlusal loading
  • direct fibroblast migration during eruption
31
Q

what are cell rests of malassez?

A

remnants of epithelial root sheath of hertwig

32
Q

what do cell rests of malassez form?

A

a plexus which surrounds the tooth ( close to the cementum )

33
Q

what are the cell rests of malassez thought to prevent?

A

ankylosis - pathology where there is no PDL just straight attachment bone to teeth

34
Q

what can possibly form from cell rests of malassez?

A

cyst formation later in life

35
Q

what is the alveolar bone?

A

Maxillary & mandibular bone that surrounds + Supports the tooth roots

36
Q

what does the alveolar bone consist of?

A

Cancellous (Trabecullar /Spongy) bone covered by a thin layer of compact (cortical) bone

37
Q

what inserts into alveolar bone?

A

PDL fibres (sharply fibres)

38
Q

what bone is more dense?

A

cortical bone

39
Q

what is the bundle bone?

A
  • Part of the bone to which the tooth attaches (tooth socket)
  • bundle bone is heavily perforated by blood vessels
40
Q

what is the alternative name for bundle bone?

A

cribriform plate

41
Q

what do the cribriform plate (bundle bone) look like on the radiograph?

A

shows up as a narrow radio-opaque white line around the root called the lamina dura

42
Q

what does the loss of the lamina dura suggest?

A

pathology

43
Q

Describe the turnover of alveolar bone.

A

-Constant turnover :

under influence of systemic and local factors

44
Q

How does alveolar bone remodel?

A

Can remodel in response to functional demands

45
Q

What effect does resorption factors have?

A

target osteoblasts which then instruct osteoclasts to remove bone

46
Q

what is cementum?

A

Mineralised tissue with a similar composition to bone which covers the root surface

47
Q

what are the features of the cementum?

A
  • less mineralised than bone and dentine
  • avascular (no blood vessels or lymph vessels)
  • not innervated
48
Q

what is the cementum site of anchorage?

A

PDL fibres onto teeth ( sharpeys fibres)

49
Q

what are the 2 types of cementum?

A
  • cellular cementum

- acellular cementum

50
Q

What tissue homeostasis?

A
  • Controlled synthesis & breakdown of tissue which ensures the maintenance of the composition, volume & it’s integrity.
  • Also allows ability to respond to functional demands
51
Q

Describe the tissue homeostasis of epithelium.

A
  • Oral epithelial keratinocytes are continually shed.

* In health these are replaced by an equal number of cells from cell division in the basal cell layer

52
Q

what do stem cells in the epithelium have the ability to do?

A

cells in the basal layer retain an ability to divide throughout life

53
Q

what are stem cells essential for?

A

for renewal of the epithelium = Turnover

54
Q

Epithelial turnover is influenced by factors that affect the rate of what?

A
  • cell division
  • maturation
  • movement of cell through the prickle cell layer
  • desquamation
55
Q

what systemic hormones affect epithelial turnover?

A
  • oestrogens (increases)
  • adrenaline (reduces)
  • corticosteroids (reduces)
56
Q

what are more important than systemic hormones?

A

local factors

57
Q

what are cytokines produced by and what effect do they have?

A

Cytokines are proteins/glycoproteins produced by various cell types which can regulate growth & differentiation of other cells (at least 3 cytokines affect epithelial turnover)

58
Q

what cytokines stimulate keratinocytes division?

A
  • transforming growth factor alpha (TGFa)

- Epidermal growth factor (EGF)

59
Q

what cytokines inhibit keratinocytes division?

A

-Transforming growth factor beta (TGFB)

60
Q

what on top of epithelium , undergoes continuous turnover?

A

connective tissue

61
Q

what is threat of turnover of connective tissue?

A
  • PDL 5x > alveolar bone

- PDL 15x > skin

62
Q

what are fibroblasts responsible for?

A

-synthesis & degradation of collagen + extracellular matrix
(secrete enzymes that breakdown collagen = collagenases)

63
Q

what do collagenous cleave?

A
  • cleave segments off the collagen fibrils which are taken up by the fibroblasts.
  • Fibroblasts then degrade these intracellularly (lysosomal enzymes).
64
Q

what do fibroblasts regulate the activity of?

A

Metalloproteinase enzymes, such as collagenases, by also releasing Tissue inhibitors of metalloproteinases (TIMP):
(TIMPs prevent unwanted /uncontrolled tissue damage by collagenases)

65
Q

what is involved in the regulation of connective tissue turnover?

A

cytokines are probably important ( little known)

66
Q

what cytokines stimulate connective tissue turnover?

A
  • platelet derived growth factor (PDGF)
  • Fibroblast growth factor (FGF)
  • Transforming growth factor beta (TGF-B)
67
Q

what cytokines inhibit connective tissue turnover?

A
  • interleukin - 1

- interferon gamma

68
Q

Describe the homeostasis of bone.

A 
•Turns over throughout life.
•Volume relatively constant.
•Able to remodel which is important for:
>maintaining blood calcium levels
>adaption to changes in mechanical loading
69
Q

Describe the homeostasis of local periodontal bone resorption.

A

-Factors thought to stimulate local bone resorption (in vitro) :> prostaglandin
>interleukin
>tumour necrosis factor alpha
>tumour necrosis factor beta

70
Q

when are these factors produced in bone resorption?

A

•These factors are produced during inflammatory & immune responses.

(•Important in periodontal disease?
•Important in normal tissue homeostasis?)

Endemic Oral disease (13 decks)

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