(1) Anatomy and Histology of the Periodontium - periodontal ligament (ground substance, cells, nerve and blood supply)

Question 1

What secretes the ground substance?

Answer 1

fibroblasts

Question 2

What is the role of the fibroblasts?

Answer 2

cells responsible for forming the collagen for collagen fibres

Question 3

What are the components of the ground substance?

Answer 3

• Hyaluronate glycosaminoglycans.
• Proteoglycans
• Glycoproteins

Question 4

What are the proteoglycans comprising the ground substance?

Answer 4

1) Proteodermatan sulphate

2) PG1 (contains hybrids of chondroitin sulphate dermatan sulphate).

Question 5

What are the glycoproteins which comprise the glycoproteins?

Answer 5

1) fibronectin

2) tenascin

Question 6

What is the role of the ground substance in the periodontal ligament?

Answer 6

maintain pressure and function of the PL

Question 7

Name the 6 types of cell in the periodontal ligament

Answer 7

1. Fibroblasts
2. Cementoblasts.
3. Osteoblasts
4. Osteoclasts and cementoclasts.
5. Epithelial cells
6. Immune cells

Question 8

What is the role of fibroblasts in the PL?

Answer 8

Form fibres

Responsible for the regeneration of the periodontal ligament.

Role in adaptive responses to mechanical loading.

Question 9

What is the shape of the fibroblasts?

Answer 9

vary

don’t always see the spindle shape

prominent nucleoli

Question 10

Are fibroblasts active or inactive?

Answer 10

active

lots of synthesising organelles

Question 11

Fibroblasts produce collagen, what else do they do with regard to collagen?

Answer 11

Collagen degradation (fibroblasts are also fibroclastic).

Question 12

Apart from collagen, what other substances do fibroblasts secrete secrete?

Answer 12

1. matrix metalloproteinases
2. tissue inhibitors
3. metalloproteinases.

Question 13

What is the role of collagen?

Answer 13

help maintain the structural framework of tissues.

Question 14

What regulates collagen production from fibroblasts?

Answer 14

Collagenase production is regulated by exposure of cytokines.

Question 15

Where do cementoblasts line?

Answer 15

the outer surface of the cementum

Question 16

Are cementoblasts active?

Answer 16

Yes, but produce cementum at a very slow pace

Question 17

What is formed at a higher rate, acellular or cellular cementum?

Answer 17

cellular

Question 18

Where are osteoblasts located?

Answer 18

line the alveolar bone

line the tooth socket

Question 19

What is the role of osteoblasts?

Answer 19

form bone

protein synthesising organelles

prominent where there is active bone formation

active protein formation

Question 20

What do osteoblasts look like when they are active/inactive?

Answer 20

active = basal round nucleus
inactive = flat

Question 21

What type of section is shown?

Answer 21

decalcified (can see cells)

Question 22

Name structures A-D and what are the black and white arrows pointing to?

Answer 22

Decalcified section.

A) Alveolar bone.
B) Periodontal ligament.
C) acellular cementum.
D) Dentine.

White arrows point to osteocytes.

Black arrows point to osteoclasts in Howship’s lacunae.

Question 23

What do osteoclasts and cementoclasts arise from?

Answer 23

blood macrophages

Question 24

Are osteoclasts and cementoclasts small mononuclear or giant multinuclear?

Answer 24

they can be both

Question 25

What is the brush border of cemento and osteoclasts?

Answer 25

striated part of the cell that is adjacent to bone, they represent microvilli.

Question 26

What is in the vesicles of osteo and cementoclasts?

Answer 26

acid phosphatase

Question 27

Where are Giant multinucleated osteoclasts found?

Answer 27

Howship’s lacunae in bone.

Question 28

What is the role of osteoclasts?

Answer 28

reabsorb/ breakdown cementum

Question 29

What are the epithelial cells rests of malassez?

Answer 29

remnants of the structures that formed the root of the tooth they don't regrade completely after tooth has formed

Question 30

Are the epithelial cells rests of malassez harmful?

Answer 30

No find them within the periodontal ligament

Question 31

What is the basal lamina?

Answer 31

extracellular structures found closely apposed to the plasma membrane on the basal surface of epithelial and endothelial cells and surround muscle and fat tissues.

Question 32

What is the structure of epithelial cell rests of Malassez?

Answer 32

closely packed cuboidal cells

Question 33

Why are epithelial cell rests of the Malassez important?

Answer 33

If there is an inflammation of some sort and there are inflammatory molecules such as cytokines and growth factors They can be induced to grow and cause cyst formation

Question 34

Which cells can cause cyst formation?

Answer 34

epithelial cell rests of the Malassez

Question 35

What cells are the arrows pointing to here?

Answer 35

epithelial cell rests of the Malassez

Question 36

What are immune cells in the periodontal ligament?

Answer 36

Macrophages Mast cells Eosinophils

Question 37

What supplies blood to the periodontal ligament? (arteries)

Answer 37

Superior and inferior alveolar arteries.

Question 38

What is the difference between the Superior and inferior alveolar arteries?

Answer 38

superior = maxillary bone inferior = mandibular bone

Question 39

How do the inferior and superior alveolar arteries supply the PDL?

Answer 39

Arteries perforating the alveolar bone. Through the neurovascular bundle entering the apical region of the pulp.

Question 40

Where are the blood vessels located in the periodontal ligament?

Answer 40

Major vessels between principal fibres.

Question 41

Where are the capillary plexus found in the PDL?

Answer 41

Capillary plexus around teeth.

Question 42

Do veins accompany the arteries?

Answer 42

NO

Question 43

What are fenestrations?

Answer 43

an arterial anatomic variant where a segment of a single vessel divides into at least two channels, each comprising endothelial and muscular layers (they may share the adventitia) that coalesce to a single lumen along its more distal course.

Question 44

Why are fenestrations important in supplying the PL?

Answer 44

They allow immune cells migrate into the periodontal ligament when needed

Question 45

Where would you find intra-alveolar venous networks?

Answer 45

prominent around the apex of the alveolus.

Question 46

What do the blue, purple and green arrow point to?

Answer 46

blue = blood vessel purple = endothelial cells green = fenestration

Question 47

Where does the nerve supply of the periodontal ligament come from?

Answer 47

comes through the alveolar bone or through the neurovascular bundle which comes through the apex of the root, which divides into the pulp and the periodontal ligament

Question 48

What types of nerve fibres supply the PL?

Answer 48

sensory autonomic

Question 49

What do the sensory nerve fibres of the PL allow?

Answer 49

nociception mechanoreception

Question 50

What do the autonomic nerve fibres control in the PL?

Answer 50

BLOOD VESSELS

Question 51

Where do the nerve fibres enter the PL?

Answer 51

apical region others enter through the alveolar wall