Periodontal ligament & GFL

Question 1

Functions of the GFL

Answer 1

Provide rigidity and dentistry to the marginal gingiva
Acts as a periosteum for the interproximal crystal alveolar bone
Provide 1/2 of the biologic width (about 2mm)
Act as a protective barrier for the crystal alveolar bone against the spread of gingival inflammation
Inhibit the apical migration of the junctional epithelium

Question 2

GFL fiber groups

Answer 2

Dentogingical 
Dentoperiosteal
Alveologingical 
Circular
transseptal
Semicircular 
Transgingival

Question 3

What is the biological width

Answer 3

The area of the junctional epithelium and gingival fiber ligament attached to the root of a tooth. It extends from the most coronal attachment of the junctional epithelium to the crystal alveolar bone

Question 4

Violation of the biological width due to placement of overextended restoration margins will result in ____ ______

Answer 4

chronic inflammation

Question 5

Chronic inflammation + time due to violation of the biological width will cause

Answer 5

loss of supporting alveolar bone with formation of a diseased periodontal pocket

Question 6

Functions of the PDL

Answer 6

Supportive 
Regenerative
Nutritional 
Sensory 
Protective

Question 7

PDL is derived from what

Answer 7

ectomesenchymal cells (neural crest) in the intermediate zone of the dental follicle.

Question 8

Cells in the most peripheral zone (outer) of the dental follicle give rise to what?

Answer 8

Alveolar bone proper

Question 9

Cells in the most proximal zone (inner) of the dental follicle give rise to what?

Answer 9

Cementoblasts

Question 10

Resident cell populations of the PDL are

Answer 10

Fibroblasts
Osteroblasts
Cementoblasts
Macrophages 
Undifferentiated mesenchymal cells 
Endothelial cells
Epithelial cells

Question 11

X-sectional views of the PDL show the arrangement of the fibers the resist what

Answer 11

torque-like forces on the tooth

Question 12

Apical PDL fiber group fxn is?

Answer 12

Resist vertical force

Question 13

Oblique PDL fiber group fxn is?

Answer 13

Resist intrusive force

Question 14

Horizontal PDL fiber group fxn is?

Answer 14

Resist horizontal & tipping force

Question 15

Alveolar crest PDL fiber group fxn is?

Answer 15

Resist vertical force

Question 16

Interradicular PDL fiber group fxn is?

Answer 16

Resist vertical and lateral force

Question 17

Transseptal GFL fiber group fxn is?

Answer 17

Resist tooth separation

Question 18

Dentogingival GFL fiber group fxn is?

Answer 18

Resist gingival displacement

Question 19

Alveologingival GFL fiber group fxn is?

Answer 19

Resist gingival displacement

Question 20

Circumferential GFL fiber group fxn is?

Answer 20

Resist gingival displacement

Question 21

Semicircular GFL fiber group fxn is?

Answer 21

Resist gingival displacement & tooth separation

Question 22

Orthodontic Relapse

Answer 22

Transseptal fibers
Semicircular fibers
PDL Principle fiber groups
PDL have memory & want to move back to OG place

Question 23

The PDL interstitial spaces are a souvenir of mesenchymal cells that can differentiate into

Answer 23

Cementoblasts
Osteoblasts
Fibroblasts

Question 24

Cementoblasts

Answer 24

Regeneration and repair of cementum following injury.

Continuous physiologic deposition cementum

Question 25

Osteoblasts

Answer 25

Continuous physiologic remodeling of supporting alveolar bone
Regeneration and repair of bone following orthodontic therapy or disease

Question 26

Fibroblasts

Answer 26

Various phenotypes of fibroblasts are involved in collagen production and physiologic collagen degradation

Question 27

Ankylosis

Answer 27

Fusion of cementum directly with the surrounding alveolar bone (turns cementum into bone) without the intervening PDL. Usually from a reparative response to PDL injury

Question 28

Degree of injury dictates the type of response of the PDL

Answer 28

Significant = cells respond are from the surrounding alveolar bone - making more bone - ankylosis 
Slight = cells are from the PDL - these cells have the potential to regenerate all tissues involved in tooth support and the PSL will be restored.