Periodontal Ligament Flashcards

The student shall be able to define PDL and describe its composition and functions in detail. The student shall be able to memorise blood supply, lymphatics and nerve supply of PDL. The student will also determine the age changes of PDL

1
Q

Periodontium comprises of?

A

Cementum,
Periodontal ligament,
Bone lining the tooth socket
That part of the gingiva facing the tooth

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2
Q

The average width of periodontal ligament is?

A

0.21 to 0.38mm

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3
Q

Periodontal ligament is thinnest around which part of the root

A

Middle third. It is widest at the region near alveolar crest followed by the apical third. This gives it an hour-glass shape

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4
Q

The dental follicle cells are composed of which cells?

A

Mesenchymal cells of the dental follicle proper and the perifollicular mesenchyme

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5
Q

Which of the following types of cells are present in a healthy periodontal ligament?

A
Synthetic 
Resorptive cells
Progenitor 
Defence cells
Epithelial cell rests of Malassez
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6
Q

What is Periodontal Ligament Homeostasis

A

 Uniqueness that the PDL width remains more or less constant inspite of it lying between 2 hard structures.
 This is due to various molecules secreted by various cells in the PDL.
1. Msx2
2. Balance between bone sialoprotein and osteopontin
3. Matrix ‘Gla’ protein.
4. RGD-cementum attachment protein
5. Prostaglandins.
6. PDL can increase in width when functional demand is increased and vice versa.

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7
Q

What are the typical characteristics of a periodontal ligament fibroblasts?

A

 They are derived from ectomesenchyme of dental papilla as well as dental follicle
 They appear as ovoid or elongated cells with pseudopodia like process (cilia).
 The ones close to the bone side have abundant alkaline phophatase.
 The ones close to cementum are derived from dental papilla and the ones close to bone from perivascular mesenchyme
 They are arranged with long axis parallel to the direction of collagen fibrils.

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8
Q

What is incorporated into collagen polypeptides known as procollagen molecules

A

Proline

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9
Q

What is the shape of osteoblasts?

A

Cuboidal

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10
Q

In Osteoclasts, the part of plasma membrane lying adjacent to the bone that is being resorbed is?

A

Ruffled

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11
Q

Degradation of collagen is considered to be intracellular event. True or False?

A

True

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12
Q

Which are the resorptive cells of PDL?

A

Osteoclasts, Fibroblasts and Cementoclasts

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13
Q

Progenitor cells are ____ in size and nucleus is ___ faced.

A

Small,

closed

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14
Q

What are epithelial rests of Malassez?

A

Remnants of Hertwig Epithelial Root Sheath

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15
Q

Epithelial rests of Malassez may calcify to become?

A

Cementicles

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16
Q

As part of an immune response to foreign pathogens, Mast cells release____

A

Histamine

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17
Q

Numerous cytoplasmic granules stain with which dyes

A

Basic dyes

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18
Q

Which cells phagocytose dead cells?

A

Macrophages

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19
Q

In Eosinophils, Granules have crystalloid structures and exhibit bright red staining properties with which dyes?

A

Acidic dyes like eosin

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20
Q

The amount of collagen in a tissue can be determined by its ___content

A

Hydroxyproline

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21
Q

Increased levels of hydroxyproline is seen in which type of collagen?

A

Type III

22
Q

Which are the different principal group of Fibers in PDL?

A

Alveolar crest, Horizontal, Oblique, Apical, Inter-radicular

23
Q

____group of fibers extend obliquely from cementum just beneath junctional epithelium to the alveolar crest

A

Alveolar crest

24
Q

____group of fibers are restricted to the coronal one fourth of PDL space

A

Horizontal

25
Q

____group of fibers are the most numerous fibers and occupy 2/3rd of the ligament

A

Oblique

26
Q

Oblique group of fibers restrict which forces?

A

vertical and intrusive

27
Q

Apical group of fibers restrict which forces?

A

luxation and prevent tooth tipping

28
Q

___fibers are not seen on incompletely formed roots

A

Apical

29
Q

Inter-radicular group of fibers restrict which forces?

A

tooth tipping, torquing and luxation

30
Q

___ fibers are lost in cases of gingival recession leading to exposure of furcation

A

Inter-radicular

31
Q

Few Sharpey’s fibers pass uninterruptedly through the bone of the alveolar process to continue as principal fibers of the adjacent periodontal ligament. These are known as

A

Transalveolar

32
Q

What are Sharpey’s fibers?

A

embedded portions of fibers in cementum and bone

33
Q

Which are elastic fibers?

A

Elastin, Elaunin, Oxytalan

34
Q

The ligament fibers which runs from the cementum of one tooth over the crest of the alveolus to the cementum of the adjacent tooth are known as

A

Transseptal fibers

35
Q

Which are Immature elastic fibers?

A

Elaunin, Oxytalan

36
Q

Elastin fibers consists of which amino acids?

A

Glycine, Proline, Hydroxyproline

37
Q

____ are fine immature collagen fibers with argyrophilic staining properties and are related to basement membrane of blood vessels and epithelial cells which lie within the periodontal ligament

A

Reticular fibers

38
Q

___ are small collagen fibers associated with the large principal collagen fibers and run in all directions

A

Indifferent fiber plexus

39
Q

The ground substance of periodontal ligament consists of___

A

Glycosaminoglycans, Proteoglycans, Glycoproteins

40
Q

The constituents of ground substance of periodontal ligament are secreted by

A

Fibroblasts

41
Q

Which is the main type of glycosaminoglycan in PDL ground substance?

A

Hyaluronan

42
Q

Which is the predominant glycoprotein in the ground substance of PDL?

A

Fibronectin

43
Q

_____ has been found principally in the basement membrane of the epithelial cell rests of Malassez

A

Undulin

44
Q

PDL in maxilla receives its blood supply from which vessel?

A

Superior alveolar artery

45
Q

PDL in mandible receives its blood supply from which vessel?

A

Inferior alveolar artery

46
Q

Which lymph nodes drain labial and lingual gingiva of mandibular incisors?

A

Submental

47
Q

Which lymph nodes drain maxillary palatal gingiva?

A

Deep cervical.

48
Q

Which nerve fibers are associated with nociception, mechanoception and proprioception?

A

Sensory

49
Q

Where are cementicles found

A

PDL

50
Q

Which are functions of PDL?

A

Supportive, Sensory, Nutritive, Homeostatic, Eruptive & Physical

51
Q

Deficiency of which Vitamin may lead to failure of synthesis and replacement of collagen, ultimately leading to loss of tooth.

A

Vitamin C

52
Q

Which theories which explain how the impact of Occlusal forces is transmitted atraumatically to the bone are?

A

Tensional and Viscoelastic system theory