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121 Histology & Embryology > PDL > Flashcards

PDL Flashcards

1
Q

General characteristics of the PDL

A

Soft CT composed of collagen
Principle fibers of periodontium
Sharpey’s fibers= terminal ends of principle fibers

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2
Q

What are the functions of the PDL?

A 
Supportive
Nutritive
Formative
Protective
Sensory
Hemostatic
Eruptive movement
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3
Q

What are the supportive functions of PDL?

A

Supports root in alveolus & resists forces

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4
Q

What are the nutritive functions of PDL?

A

Carries nutrients to cementum, ABP and PDL

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5
Q

What are the formative functions of PDL?

A

Forms and resorbs cementum, ABP and PDL

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6
Q

What are the protective functions of PDL?

A

Shock absorber for BV, lymphatics and nerves

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7
Q

What are the sensory functions of PDL?

A

Pain, touch, temp and proprioceptive

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8
Q

What are the hemostatic functions of PDL?

A

Maintains constant width of PDL space

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9
Q

What are the eruptive movement functions of PDL?

A

Assists in eruptive movement

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10
Q

Where is the PDL located? Where is it widest and thinnest?

A

Located between the ABP and cementum

Widest at alveolar crest and apex, thinest at midpoint of root

Thin, limited space, narrows with age

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11
Q

What is the embryonic origin of the PDL?

A

Neuroectoderm/Neural crest cells of the head and neck

Ectomesenchyme of neural crest cells give rise to dental sac–> dental sac/follicle gives rise to fibroblasts that form the principle fibers of the PDL

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12
Q

What cells is the PDL composed of?

A 
Fibroblasts (most abundant)
Mesenchyme cells
Cementoblasts
Osteoblasts
Cell rests of Malassez

Additional cells: mast, macrophages, lymphocytes, plasma cells

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13
Q

Fibroblasts function in PDL

A

Produce/resorb collagen, maintains PDL fibers and space

Produces ground substance

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14
Q

Function of mesenchyme cells in PDL

A

Form fibroblasts, cementoblasts, osteoblasts

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15
Q

Where are cementoblasts found in PDL?

A

Closest to cementum

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16
Q

Where are osteoblasts found in PDL?

A

Closest to ABP

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17
Q

Where are cell rests of Malassez located in PDL and what is their function?

A

Found closest to the cementum

May participate in PDL repair/regeneration- potential to form cysts

18
Q

What are the 5 principle fibers of the PDL?

A 
Alveolar crest fibers 1st group
Horizontal fibers 2nd group
Oblique fibers 3rd group
Apical fibers 4th group
Interradicular fibers 5th group
19
Q

Where are alveolar crest fibers located and what types of forces do they resist?

A

Apex of alveolar crest to cementum at cervix of root

Resists tilting, occlusal, avulsive and rotational forces

20
Q

Where are horizontal fibers located and what types of forces do they resist?

A

Extend horizontally from ABP to cementum just apical to alveolar crest fibers- coronal 1/3 of root

Resist tilting and rotational forces

21
Q

Where are oblique fibers located and what types of forces do they resist?

A

Largest group

Extend obliquely from ABP to cementum just apical to horizontal fibers- mid portion of root to apical 1/3
Acute angle to horizontal fibers

Most resistant to occlusal and some rotational forces

22
Q

Where are apical fibers located and what types of forces do they resist?

A

Extend from apical ABP to apical cementum- parallel with long axis of root

Resistant to avulsive and rotational forces

23
Q

Where are interradicular fibers located and what types of forces do they resist?

A

*only in multi rooted teeth

Extend from apex of interradicular septum ABP to cementum of furcation area

Resist tilting, occlusal, avulsive, and rotational forces

24
Q

What are oxytalan fibers? Where are they located?

A

Support the BV and alleviate some masticatory stress on the BV

Positioned in various angles to principle fibers

25
Q

What is in the ground substance of PDL and what is its function?

A

Glycoproteins, glycosaminoglycans and bound water

Acts as a hydraulic system during mastication- equalizes occlusal forces by redistributing them throughout the PDL

26
Q

Where are gingival ligaments found?

A

Found in CT of the gingiva, NOT THE PDL

Not considered part of the periodontium

Supports gingiva

Specific orientation that forms 5 distinct groups

27
Q

What are the 5 groups of gingival ligaments?

A 
Circular fibers
Alveogingival fibers
Dentoperiosteal fibers
Dentogingival fibers
Transseptal fibers/Interdental  fibers
28
Q

Where are the circular fibers?

A

Encircle the cervix of the tooth, found in CT of free gingiva and interdental papilla

29
Q

Where are alveogingival fibers located?

A

Extend through CT (lamina propria) of free/attached gingiva to alveolar crest of ABP

30
Q

Where are dentoperiosteal fibers found?

A

Extend throught CT of attached gingiva from alveolar cortical plate to cervical cementum

31
Q

Where are dentogingival fibers found?

A

Extend from CT of free/attached gingiva to cervical cementum

32
Q

Where are transseptal/interdental fibers found?

A

Extend from cervical cementum of tooth through CT of interdental papilla to cervical cementum of adjacent tooth

33
Q

What is the main blood supply to the PDL?

A

Maxillary artery

34
Q

What are the 3 sources of blood supply to the PDL?

A

Dental arteries- branch before entering apical foramen- clastic cells for repair

Alveolar bone/cribiform plate- perforating arteries of nutrient canals Zucker/Hersch

Gingiva- blood vessels of supporting CT

35
Q

Where does venous drainage of PDL occur?

A

In capillary bed in apical region

36
Q

What nerve innervates the PDL?

A

Trigeminal (5th cranial)

Superior & inferior alveolar

Myelinated nerves mediate proprioception and pain

Non-myelinated nerves control lumen size of PDL blood vessels

37
Q

What are cementicles and where are they found?

A

Excementosis- hypercalcification of dead cells, collagen, debris etc

Free- in PDL
Attached- cementum to PDL
Interstitial- completely embedded in cementum

38
Q

PDL remodeling in humans

A

Entire length of principle fibers continuously remodeling

NO INTERMEDIATE PLEXUS- only occurs in some rodents

39
Q

What is hypofunction of PDL?

A

PDL narrows/thins

Tooth/teeth out of occlusion- may overerupt or be lost

Loss of functional stimuli, PDL atrophies

Lamina dura thins and trabeculae decrease in #

40
Q

What is hyperfunction of PDL?

A

PDL thickens
Tooth/teeth are in occlusion w/ heavy occlusal forces (not traumatic)

PDL undergoes hypertrophic changes

Lamina dura remains & trabeculae increase in #- supporting alveolar bone becomes denser

41
Q

What happens from occlusal trauma?

A

PDL is destroyed & PDL space widens

Clenching/bruxism (sever, long)
PDL crushed causing hemorrhage/necrosis of fibers
Resorption of ABP, cemental tears, root resorption, fractures, abfraction
Teeth involved may become mobile or lost

42
Q

What results from clastic activity of cementoclasts and odontoclasts and is initiated by the PDL?

A

External root resorption

Due to trauma or infection

121 Histology & Embryology (15 decks)

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