Gingival Fiber & Periodontal Ligament

Question 1

Functions of the GFL: (5)

Answer 1

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

Question 2

GFL Fiber Groups (7)

Answer 2

• Dentogingival
• Dentoperiosteal
• Alveologingival
• Circular
• Transseptal
• Semicircular
• Transgingival

Question 3

The biological width is the

Answer 3

area of junctional epithelium
and gingival fiber ligament attached to the root of a
tooth. Thus, the biological width extends from the most
coronal attachment of the junctional epithelium to the
crestal alveolar bone.

Question 4

Violation of the biological width due to placement of

overextended restoration margins will result in

Answer 4

chronic
inflammation and, given sufficient time, induce loss of
supporting alveolar bone with formation of a diseased
periodontal pocket.

Question 5

Functions of the PDL: (5)

Answer 5

  Supportive 
  Regenerative 
  Nutritional 
  Sensory 
  Protective

Question 6

The PDL is derived from

Answer 6

the ectomesenchymal cells (neural

crest) in the intermediate zone of the dental follicle.

Question 7

Cells
in the most peripheral zone (outer) of the dental follicle give
rise to the — and those in the most
proximal (inner) give rise to —

Answer 7

alveolar bone proper

cementoblasts

Question 8

The indifferent fiber plexus (arrows) consists of

Answer 8

small
diameter collagen fibers in random orientation that
provide support for the principle fiber groups.

Question 9

Resident Cell Populations of the PDL (7)

Answer 9

 Fibroblasts 
 Osteoblasts 
 Cementoblasts 
 Macrophages 
 Undifferentiated mesenchymal cells 
 Endothelial cells 
 Epithelial cells

Question 10

PDL Fiber Group: Apical

Function:

Answer 10

Resist vertical force

Question 11

PDL Fiber Group: Oblique

Function:

Answer 11

Resist intrusive force

Question 12

PDL Fiber Group: Horizontal

Function:

Answer 12

Resist horizontal & tipping force

Question 13

PDL Fiber Group: Alveolar Crest

Function:

Answer 13

Resist vertical force

Question 14

PDL Fiber Group: Interradicular

Function:

Answer 14

Resist vertical & lateral force

Question 15

all PDL. fiber groups tend to resist

Answer 15

rotational forces

Question 16

GFL Fiber Group: Transseptal

Function:

Answer 16

Resist tooth separation

Question 17

GFL Fiber Group: Dentogingival

Function:

Answer 17

Resist gingival displacement

Question 18

GFL Fiber Group: Alveologingival

Function:

Answer 18

Resist gingival displacement

Question 19

GFL Fiber Group: Circumferential

Function:

Answer 19

Resist gingival displacement

Question 20

GFL Fiber Group: Semicircular

Function:

Answer 20

Resist gingival displacement

& tooth separation

Question 21

Orthodontic Relapse

Answer 21

 Transseptal Fibers
 Semicircular Fibers
 PDL Principle Fiber Groups

Question 22

The PDL interstitial spaces are a source of mesenchymal

cells that can differentiate into: (3)

Answer 22

cementoblasts
osteoblasts
fibroblasts

Question 23

Cementoblasts (2)

Answer 23

• Regeneration and repair of cementum following injury

* Continuous physiologic deposition of cementum

Question 24

Osteoblasts (2)

Answer 24

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

Question 25

Fibroblasts (1)

Answer 25

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

Question 26

Ankylosis:

Answer 26

Fusion of cementum directly with the surrounding alveolar

bone, without the intervening PDL

Question 27

ankylosis is usually a

Answer 27

reparative response to PDL injury

Question 28

(2) dictate

the type of response

Answer 28

The degree of injury, and the type of cells that respond

Question 29

if the injury is significant, and the cells that respond
are from the surrounding — —, the result will be
ankylosis

Answer 29

alveolar bone

Question 30

if the injury is slight, and the responding cells are from the
PDL (i.e. undifferentiated cells), these cells have the
potential to

Answer 30

regenerate all tissues involved in tooth

support, and the PDL will be restored

Question 31

The wound healing response is similar to the

trauma response of the PDL. (3)

Answer 31

1. Undifferentiated cells migrate into the area, as
   macrophages and PMN’s remove damaged
   tissues.
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 the
   necessary cells reach their target.

Question 32

Guided Tissue Regeneration

Answer 32

A surgical technique of regenerating the periodontal attachment
apparatus on periodontally involved teeth, which uses the
differentiation of mesenchymal cells in the interstitial spaces of
the PDL and marrow spaces of adjacent alveolar bone.

Question 33

In Guided Tissue Regeneration, the membrane excludes 
gingival epithelial tissues from 
the deeper part of the wound, 
and allows only cells from the 
existing --- to

Answer 33

PDL

repopulate the wound

Question 34

The lateral periodontal cyst typically occurs along the

Answer 34

lateral root surface.

Question 35

Lateral Periodontal Cyst is believed to arise from

Treatment consists of

Answer 35

epithelial rests (epithelial rest of Malassez in the PDL), when
stimulated.
surgical removal.

Question 36

The gingival cyst is derived from odontogenic
epithelium located in the connective tissues
of the gingiva known as the

Answer 36

epithelial rests

of Serres.

Question 37

Orthodontic tooth movement results in

Answer 37

compression of the PDL on the side of the
root corresponding to the direction of
movement. Compression of the PDL
results in loss of principle fiber orientation
and resorption of adjacent bone.

Question 38

The PDL on the tooth root opposite the

compression side is characterized by

Answer 38

tension or stretching of the PDL principle
fibers. Controlled tension results in bone
apposition.

Question 39

Trauma From Occlusion:

Answer 39

excessive functional stresses
placed on a tooth by an antagonist (or removable prosthesis)
that exceeds the limits of physiologic adaptation.
• Resorption of alveolar bone parallel to the long axis of the root
• A PDL that is wider than normal average width (i.e., > 0.17 mm in
adult)
• Tooth mobility

Question 40

Disuse Atrophy:

Answer 40

A tooth with no occlusal antagonist will
exhibit:
• A significant decrease in density of bony trabeculae
• Decreased width of the PDL (< 0.17 mm)
• Loss of orientation of the principle fibers of the PDL
• Increased volume of the bone marrow spaces