Periodontium Flashcards

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1
Q

What is the periodontium?

A

the periodontium is the tissues surrounding and supporting the teeth

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2
Q

What does the periodontal tissues consist of

A

Cementum
Gingiva
Alveolar bone
Periodontal ligament

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3
Q

What are the functions of the periodontium

A

Retaining the tooth in its socket
Resisting masticatory loads and transferring them to the bone
As a defensive barrier protecting tissues against threats from the oral environment

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4
Q

What is the junctional epithelium

A

The physical barrier separating the body tissues from the oral environment

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5
Q

Why is the epithelial attachment in the oral environment unique

A

It is the only breach in the body’s surface

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6
Q

What is cementum

A

Cementum is a bone like layer of mineralized tissue which is deposited incrementally on the surface of the root

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7
Q

How is cementum similar to bone

A

Both have a collagen matrix

Both have a lamellar arrangement

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8
Q

How is cementum different to bone

A

Cementum has a parallel lamellar arrangement whereas bone has a radial lamellar arrangement

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9
Q

What does cementum cover

A

root dentine

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10
Q

What does cementum provide attachment for

A

some periodontal fibres

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11
Q

What is cementum laid down by

A

cementoblasts

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12
Q

Describe cellular cementum

A

Contains cementocytes
Later formed
Present in the apical part of the root and furcation regions
Covers acellular cementum

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13
Q

Describe acellular cementum

A

No cells within it
Usually adjacent to dentine
First formed
Fibres of the PDL terminate here (sharpey’s fibres)

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14
Q

Why is the presence of cellular/acellular cementum clinically relevant?

A

the responses to treatment will be different and so success rates of treatment is linked to the presence of acellular and cellular cementum

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15
Q

what are the alternative classifications of cementum based on the histological differences

A

acellular extrinsic fibre cementum

cellular intrinsic fibre cementum

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16
Q

describe acellular extrinsic fibre cementum

A

has collagen fibres from the PDL - sharpey’s fibres

present on cervical 2/3 of the root

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17
Q

why is acellular extrinsic fibre cementum more successful when it comes to regeneration

A

it has the ability to produce anchorage which is relevant to the treatment of periodontitis

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18
Q

describe cellular, intrinsic fibre cementum

A

no sharpey’s fibres
intrinsic collagen fibres parallel to surface
has no role in tooth attachment
may represent a transitional form

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19
Q

what makes alveolar bone different to normal bone

A

it is dependent for its development and persistence upon the presence of tooth

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20
Q

what does the cortical plate form?

A

the inner lining of tooth socket

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21
Q

what does the cancellous bone contain

A

marrow

blood vessels, nerves, lymph etc

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22
Q

what are volksman canals

A

they are small openings which supply the periodontal ligament with nutrients

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23
Q

what does the periodontal ligament contain

A
cells 
extracellular matrix 
fibres 
nerves 
blood vessels
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24
Q

what makes the extracellular matrix special

A

behaves as a viscoelastic gel - gives it capacity to return to its original shape

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25
Q

what is the extracellular matrix made up of

A

hyaluronate GAGs
glycoproteins
proteoglycans

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26
Q

what are the glycoproteins in the PDL matrix

A

fibronectin

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27
Q

what are the proteoglycans in the PDL matrix

A

proteodermatan sulphate

chondroitin/dermatin SO4 hybrid

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28
Q

what are the cells in the PDL

A
fibroblasts
cementoblasts
osteoclasts
cementoclasts
epithelial cells
defence cells
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29
Q

what do fibroblasts do in the PDL

A

they generate the infrastructure and upkeep it

30
Q

what are the epithelial cells in the PDL

A

cell rests (or debris) of malassez

31
Q

what are cell rests of malassez

A

they are part of the periodontal ligament cells around a tooth
they are discrete clusters of residual cells from hertwig’s epithelial tooth sheath that did not completely disappear

32
Q

what are the sensory nerves in the PDL

A

mechanoreceptors

Nociceptors

33
Q

what are the mechanoreceptors in the PDL

A

Abeta and Adelta

they are rapidly or slowly adapting

34
Q

what do the mechanoreceptors in the PDL provide

A

proprioception; chewing control

35
Q

what are the nociceptors in the PDL

A

Adelta and C fibres

36
Q

what do the nociceptors in the PDL provide

A

protective reflexes

inhibit jaw elevator motor neurons (jaw jerk reflex)

37
Q

what do the autonomous (sympathetic) nerves allow in the PDL

A

blood vessel control

38
Q

what is the blood supply of the PDL

A

inferior and superior alveolar arteries which pass into the PDL from alveolar bone

39
Q

what is the blood supply of the gingiva

A

lingual and palatine arteries

40
Q

what are the 2 types of periodontal fibres

A

true periodontal ligament

gingival ligament

41
Q

Where are the gingival ligament fibres found

A

they are fibres mainly above the alveolar crest including free gingival fibres

42
Q

what is the periodontal ligament

A

it attaches tooth to jaw
transmits biting forces to alveolar bone
organized (regular) connective tissue

43
Q

what is the width of the periodontal ligament

A

approximately 0.2mm

44
Q

what are the PDL fibres made up of

A

collagen

oxytalan

45
Q

what types of collagen make up the PDL fibres

A

type 1 and 3

46
Q

what is the function of collagen in the PDL fibres

A

to support the tooth; load bearing

47
Q

what do the principal fibre group consist of

A

alveolodental ligament

interdental ligament

48
Q

what are the different fibres in the alveolo-dental ligament

A
alveolar crest
horizontal 
oblique
apical 
interradicular (multi-rooted teeth)
49
Q

what do the alveolar crest fibres do

A

they resist vertical and intrusive forces

50
Q

what do the horizontal fibres do

A

resist horizontal and tipping forces

51
Q

what do the oblique fibres do

A

resist vertical and intrusive forces

52
Q

what do the apical fibres do

A

resist vertical forces

53
Q

what do the interradicular fibres do

A

resist vertical and lateral movement

54
Q

what makes up the interdental ligament

A

transeptal fibres

55
Q

what do transeptal fibres do

A

resist tooth separation and connect tooth to tooth

56
Q

what do the gingival fibre group do

A

they support the free gingiva

57
Q

where are the gingival fibre group present

A

lamina propria in marginal gingiva

58
Q

what are the 4 fibres in the gingival fibre group

A

dentogingival
alveologingival
dento-periosteal
circular

59
Q

where are the dentogingival fibres

A

they extend from the cervical cementum into the free and attached gingiva

60
Q

where are the alveoli gingival fibres

A

extend from the alveolar crest into the gingiva

61
Q

where are the dento-periosteal fibres

A

extend from the cervical cementum into the alveolar crest

62
Q

where are the circular fibres

A

surround the teeth

63
Q

what are the two margins visible on the gingiva

A

gingival margin

muco-gingival margin

64
Q

what is the gingiva not attached to any bone called

A

free gingiva

65
Q

what is the gingiva attached to bone called

A

attached gingiva

66
Q

what does junctional epithelia provide

A

attachment for the gingiva to the tooth in the cervical area and forms the epithelial lined floor of the gingival sulcus

67
Q

how does junctional epithelium connect to enamel

A

through hemidesmosomes

68
Q

how do junctional epithelium connect to each other

A

desmosomes

69
Q

what is the interdental col

A

the area between two teeth that is protected by the contact point

70
Q

what is special about the epithelium in col

A

it is not keratinized due to no masticatory forces

71
Q

what type of forces is the PDL mostly subjected to

A

intrusive:

  • mastication
  • swallowing
  • speech
  • parafunction
72
Q

what type of forces are the teeth rarely subjected to

A

extrusive and horizontal forces:

  • sticky foods
  • orthodontic forces