Periodontal Ligament Flashcards

1
Q

What is the gingival fiber ligament?

A

ligament that attach crown of tooth to the periodontal ligamnet

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2
Q

What are the functions of the GFL?

A

-provide rigidity and density to marginal gingiva
-act as periosteum for interproximal crestal alveolar bone
-provide one half of the biologic width
-act as a protective barrier for crestal alveolar bone against the spread of gingival inflammation
-inhibit the apical migration of junctional epithelium

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3
Q

What are the GFL fiber groups?

A

-dentogingival
-dentoperiosteal
-alevologingival
-circular
-transeptal
-semicircular
-transgingival

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4
Q

What does the transgingival giber group do?

A

hold papillae intact between the teeth

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5
Q

What is the biological width?

A

area of junctional epithelium and gingival fiber ligamnet attached to the root of the tooth
-from crest of gingiva to crest of alveolar bone

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6
Q

What is the border of the biological width?

A

most coronal attachment of the junctional epithelium to the crestal alveolar bone

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7
Q

What is caused with violation of biological width

A

chronic inflammation and potential of loss of supporting alveolar bone

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8
Q

Where is the PDL compared to GFL ?

A

more apical on the tooth compared to the GFL

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9
Q

What are the functions of PDL?

A

supportive
regenerative
nutritional
sensory
protective

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10
Q

What allows the PDL to be regenerative?

A

has undifferentiated cells that are able to be activated and differentiae into different tissues

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11
Q

What is the PDL derived frm?

A

neural crest cells

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12
Q

What zone of the dental follicle does the PDL come from?

A

the intermediate zone

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13
Q

What do cells in the outer zone of the dental follicle form?

A

alveolar bone proper

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14
Q

What do cells in the inner zone of the dental follicle form?

A

cementoblasts

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15
Q

How does the PDL help with tooth eruption:?

A

as the PDL grows, fiber groups form
-these fiber groups will contract and coronally push the tooth into the mouth

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16
Q

How does the PDL develop?

A

the fibers form, the interlock with other groups of fibers and form a mesh work
-the collagen from the fibers then gets embedded into the cementum

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17
Q

What are sharpey’s fibers”?

A

fibers of PDL that are stuck into the cementum

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18
Q

What surrounds the principle fibers of PDL?

A

indifferent fiber plexus
-small diameter collagen fibers in random orientation

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19
Q

What cell types are in the PDL?

A

-fibroblasts
-osteoblasts
-cementoblasts
-macrophages
-undifferentiated mesenchymal cells
-endothelial cells
-epithelial cells

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20
Q

What are the fiber groups of the PDL

A

-alveolar crest
-horizontal
-oblique
-apical
-interradicular

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21
Q

What is the function of apical fiber group? PDL

A

resist vertical force

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22
Q

What is the function of oblique fiber group? PDL

A

resist intrusive force

23
Q

What is the function of horizontal fiber group? PDL

A

resist horizontal and tipping forces

24
Q

What is the function of alveolar crest fiber group?: PDL

A

resist vertical force

25
Q

What is the function of interradicular fiber groups? PDL

A

resist vertical and lateral forcesWh

26
Q

What is the overall function of the PDL fiber groups?

A

to resist rotational forces

27
Q

What is the function of the transseptal fiber group? GFL

A

resist tooth separatio n

28
Q

What is the function of the dentogingival fiber gorup? GFL

A

resist gingival displacementW

29
Q

What is the function of the alveologingival fiber? GFL

A

resist gingival displacement

30
Q

What is the function of the circumferential fiber group? GFL

A

resist gingival displacement

31
Q

What is the function of the semicircular fiber group? GFL

A

resist gingival displacement and tooth separation

32
Q

What can an orthodontist do to prevent tooth movement after original adjustment?

A

cut the ligament fibers to avoid moving back
(transseptal, semicircular, and PDL principle fiber groups)

33
Q

What can the mesenchymal cells in the PDL interstital space differentiate into?

A

cementoblasts, osteoblasts, and fibroblastsd

34
Q

What do cementoblasts do?

A

regenerate and repair cementum following injury
-continuous deposition of cementum

35
Q

What do osteoblasts do?

A

-continuous remodeling of alveolar bone
-regeneration and repair of bone following orthodontic therapy or disease

36
Q

What do fibroblasts do?

A

various are involved with making collagen
(help recreate the PDL if it has been damaged )

37
Q

What is ankylosis?

A

fusion of cementum directly with the surrounding alveolar bone without the intervening PDL

38
Q

When does anklyosis typically occur?

A

when there is some type of injury (significant)
-trying to repair the PDL

39
Q

What are the steps in anklyosis?

A

-injury
-undifferentiated mesenchymal cells differnentiate into macrophages
macrophages eat the bad
-become fibroblasts
-PMN response (inflammatory)
-can either restore the PDL or lose the PDL and form bone

40
Q

What is the role of PDL in wound healing? >

A
  1. undifferentiated cells migrate into the area, macrophages and PMN remove damaged tissue
  2. fibroblasts and/or osteoblasts replace the damaged tissue
  3. a mast cell response is usually present, in which heparin and histamine are released. this inflammatory response helps necessary cells reach their target
41
Q

When there has been a disruption to the biological width, what can be done?

A

a flap can be cut into the gingiva
-some of the top layers of the ligament and bone can be disturbed
-this willl cause the activation of the mesechymal cells to fill in the area properly

42
Q

What is guided tissue regeneration?

A

a procedure done to try and repair defects in the PDL and alevolar bone
-use a membrane that blocks epithelial tissue from migrating down into the pocket
-forces the mesenchymal cells of PDL to differentiate and fill the space
-done when the PDL and bone need to be regenerated

43
Q

What is hertwigs root sheath formed from?

A

the fusion of IEE and OEE

44
Q

What is a rest of malassez?

A

a clump of cells from hertwig’s root sheath that remains in the PDL

45
Q

Where and who are Rests of Malassez most common?

A

more prevalent in apical areas of adolescents

46
Q

What are lateral periodontal cysts ?

A

cysts that form when the Rests of Malassez become activated
-can tell on radiographs because you can see the PDL through the cysts

47
Q

What are gingival cysts ?

A

cysts that form from epithelial rests of serres
-made form odontogenic epithelium
-could be connected to OKCs

48
Q

What are rests of serres?

A

groups of cells that are remnants of the dental lamina
-made of odontoblasts

49
Q

What does compression of the PDL cause ?

A

loss of principle fiber orientation and resorption of adjacent bone

50
Q

What does stretching of the PDL cause?

A

results in bone appositon
-helps to ensure the tooth stays where it is moved to

51
Q

What occurs to PDL with orthodontic treatment?

A

the PDL is stretched and compressed
-causes the moving of tooth

52
Q

What is trauma from occlusion ?;

A

excessive functional stresses placed on a tooth by antagonist that exceeds the limit of physiological adaption

53
Q

What are some of the effects of trauma from occlusion?

A

-resorption of alveolar bone parallel to the long axis of the tooth
-A PDL that is wider than normal average width
-tooth mobility

54
Q

What is disuse atrophy

A

a tooth with no occlusal antagonist with exhibit
-decrease in density of trabecular bone
-decreased width of PDL
-loss of orientation of principle fibers of the PDL
-increased volume of bone marrow spaces