08/28 - Junctional Epithelium

Question 1

During tooth eruption, the junctional epithelium is derived from ___.

Answer 1

reduced dental epithelium

Question 2

Where is the junctional epithelium the widest?

Answer 2

widest in coronal portion (15-20 cell layers) and thin toward the CEJ (3-4 cell layers)

Question 3

Which has a faster turnover rate: junctional epithelium or oral epithelium?

Answer 3

junctional epithelium

Question 4

Junctional epithelium or oral epithelium?

• larger cell size?
• larger size of intercellular space?
• larger number of desmosomes?
• keratinization?

Answer 4

• larger cell size: junctional epithelium
• larger size of intercellular space: junctional epithelium
• larger number of desmosomes: oral epithelium
• JE has potential to keratinize

Question 5

Where is the JE in comparission to the CEJ in a child? In a healthy adult? In a diseased adult?

Answer 5

• child: JE above CEJ
• healthy adult: JE at CEJ
• diseased adult: JE below CEJ

Question 6

Periodontitis occurs when the junctional epithelium ___.

Answer 6

migrates apically down the root surface

Question 7

True or false: Viable junctional epithelium is not necessary for pocket formation.

Answer 7

FALSE. It is necessary for pocket formation.

Question 8

Describe Necrotizing Ulcerative Periodontitis (NUP).

Answer 8

junctional epithelium cells die so no pocketing! bone is exposed

Question 9

What are the cells (6) of the lamina propria and describe what each does?

Answer 9

• fibroblasts: synthesize matrix and fibers
• mast cells: vasoactive substances
• macrophages: phagocytosis and synthesis
• neutrophilic granulocytes
• lymphocytes
• plasma cells

Question 10

What are the fibers (4) of the lamina propria and describe each (where they are found, etc.)?

Answer 10

• collagen: characteristic cross-banding; produced by fibroblasts, cementoblasts, and osteoclasts; most abundant
• reticulin: numerous adjacent to basement membrane; around blood vessels
• oxytalan: mostly in PDL; run parallel to long axis of tooth
• elastic: around blood vessels

Question 11

What are the 3 purposes of the gingival fibers?

Answer 11

• reinforce the gingiva
• provide resilience and tone
• maintain architectural form and integrity

Question 12

What are the 4 gingival fibers and where does each run?

Answer 12

• circular fibers: encircle tooth like a cuff
• dentogingival fibers: fan out from supra-crestal cementum into free gingiva
• dentoperiosteal fibers: run from supracrestal cementum into attached gingiva
• trasseptal fibers: run from tooth to tooth (embedded in cementum)

Question 13

True or false: The periodontal ligament is richly vascular.

Answer 13

true

Question 14

What two structures does the periodontal ligament join?

Answer 14

joins cementum and alveolar bone

Question 15

What are the 2 functions of the periodontal ligament?

Answer 15

• permits forces to be distributed

- essential for the tooth mobility

Question 16

What are the 4 fibers of the periodontal ligament?

Answer 16

• alveolar crest fibers
• horizontal fibers
• oblique fibers
• apical fibers

Question 17

What are the 6 cells of the periodontal ligament?

Answer 17

• fibroblasts: aligned along principal fibers
• osteoblasts: line bone surface
• cementoblasts: line cemental surface
• osteoclasts: multinucleated; create ruffled surface of bone
• epithelial cells
• nerve fibers
• epithelial cell rests of Mallassez: remnants of the Hertwig’s epithelial root sheath

Question 18

What is the cementum?

Answer 18

mineralized tissue covering root surface and, occassionally, small portions of the crown of the teeth

Question 19

How is cementum similar to bone? How is it different?

Answer 19

DIFFERENT:
- no blood vessels
- no lymph vessels
- no innervation
- no physiology resorption/remodeling
SIMILAR:
- continuing deposition throughout life
- collagen fibers embedded in organic matrix
- high mineral content (65%), mainly HA

Question 20

What is the difference between intrinsic and extrinsic cemental fibers?

Answer 20

• intrinsic: produced by cementoblasts; composed of fibers oriented parallel to root
• extrinsic: Sharpey’s fibers; produced by PDL fibroblasts

Question 21

What are the 3 different forms of cemental fibers? Where are each located?

Answer 21

• acellular extrinsic fiber cementum: coronal or middle portion of root
• cellular mixed stratified cementum: apical 1/3 of root and in the furcation
• cellular intrinsic fiber cementum: resorption lacunae

Question 22

True or false: Cementum thickness increases by gradual apposition throughout life.

Answer 22

true

Question 23

What is the cementum thickness in the cervical portion of the root? What is the cementum thickness in the apical portion of the root?

Answer 23

• cervical portion: 20-50 micrometers

- apical portion: 150-250 micrometers

Question 24

The alveolar bone consists of ___ bone and ___ bone formed by cells from ___ and ___.

Answer 24

• cancellous
• cortical
• from the dental follicle
• independent of tooth development

Question 25

What cells/structures are in the bone marrow?

Answer 25

adipocytes, vascular structures, and undifferentiated mesenchymal cells

Question 26

Alveolar bone remodels in response to ___ and ___.

Answer 26

- forces | - tooth movement

Question 27

In the alveolar bone, ___ produce bone matrix (osteoid) consisting of ___, ___, and ___. Osteoid undergoes mineralization by the deposition of minerals like ___.

Answer 27

- osteoblasts - collagen fibers - glycoproteins - proteoglycans - calcium and phosphate

Question 28

The dental tissue that most closely resembles bone is: a. dentin b. pulp c. cementum d. enamel

Answer 28

c. cementum

Question 29

The supraperiosteal vessels (blood supply to gingiva) are terminal branches of what 7 arteries?

Answer 29

- sublingual artery - buccal artery - mental artery - facial artery - greater palatine artery - infraorbital artery - posterior superior dental artery

Question 30

What are the 4 arteries that make up the blood supply of the periodontal tissues?

Answer 30

- dental artery - superior/inferior alveolar arteries - intra-septal artery - rami perforantes artery (terminal branch of intra-septal; penetrates alveolar bone all through the socket)

Question 31

What are the 4 relevant lymph nodes to the periodontia?

Answer 31

- submental lymph nodes - deep cervical lymph nodes - submandibular lymph nodes - jugulodigastric lymph nodes

Question 32

What are the 7 nerve branches that supply the periodontia?

Answer 32

- infraorbital nerve - sublingual nerve - posterior superior dental nerve - mental nerve - greater palatal nerve - buccal nerve - long sphenopalatine nerve