Periodontium

Question 1

What is the periodontium?

Answer 1

The tissues surrounding and supporting the teeth.

Question 2

What tissues make up the periodontium?

Answer 2

Gingiva
Periodontal ligament
Cementum
Alveolar bone

Question 3

What are the functions of the periodontium?

Answer 3

Keep the tooth in the socket.

Withstand masticatory forces

Act as a protective barrier.

Question 4

What is the role of the junctional epithelium?

Answer 4

Acts as a physical barrier between the body tissues and the oral environment.

Question 5

Where is cementum found?

Answer 5

Covering root dentine

Question 6

What is cementum laid down by?

Answer 6

Cementoblasts

Question 7

What are the 2 types of cementum?

Answer 7

Acellular

Cellular

Question 8

What cementum is formed first?

Answer 8

Acellular

Question 9

Where is Acellular cementum found?

Answer 9

cervical 2/3rd of the tooth

Question 10

Where is cellular cementum found?

Answer 10

Root apex and root furcations.

Question 11

In what type of cementum are Sharpey fibres found?

Answer 11

Acellular cementum

Question 12

What are Sharpey fibres?

Answer 12

Collagen ends from the PDL that are embedded in acellular cementum.

Question 13

What cementum has a role in tooth attachment?

Answer 13

Acellular (due to sharpey fibres)

Question 14

What is the other name for intrinsic fibre cementum?

Answer 14

Cellular cementum

Question 15

What is the other name for extrinsic fibre cementum?

Answer 15

Acellular cementum

Question 16

In what type of cementum is periodontal treatment more effective in?

Answer 16

areas with Sharpey fibres = Acellular

Question 17

What is the role of the alveolar bone?

Answer 17

Provide attachment for Sharpey fibres.

Question 18

What happens to the alveolar bone when teeth are lost?

Answer 18

Resorbed

Question 19

Describe the structure of alveolar bone (3).

Answer 19

Cortical plate lining the socket.

Inner cancellous bone with bone marrow present.

Volkmann’s nutrient canals present.

Question 20

What is the periodontal ligament?

Answer 20

Connective tissue.

Question 21

What are the functions of the PDL?

Answer 21

Transfers being forces to the alveolar bone.

Tooth attachment via Sharpey fibres.

Question 22

Describe the role of the matrix component of the PDL.

Answer 22

Acts as a viscoelastic gel that allows the ligament to return to its original shape after biting forces are applied.

Question 23

What happens to the matrix component of the PDL in periodontitis?

Answer 23

The chemical arrangement is altered and it loses its viscoelasticity.

Question 24

What cells are present in the PDL?

Answer 24

Fibroblasts - collagen and matrix secretion.

Cementoblasts - secrete cementum

Osteoclasts and cementoclasts - resorption

Epithelial cells - debris of malassez

Defence cells

Question 25

What is the nerve supply to the PDL?

Answer 25

Autonomic sympathetic - control of BV diameter. (vasoconstriction etc)

Sensory:
Abeta and Adelta fibres for;
Mechanoreception
Proprioception

C fibres and A delta fibres for;
Nociception - protective reflexes

Question 26

What is the blood supply to the PDL (and gingiva)?

Answer 26

PDL: Superior and inferior branch of the alveolar artery.

Gingiva: Lingual artery and palatine artery.

Question 27

Name the true periodontal ligaments.

Answer 27

Alveolar crest
Horizontal
Oblique
Apical

Question 28

Where are the true PDL found?

Answer 28

At or apical to the alveolar crest.

Question 29

Where are gingival ligament fibres found?

Answer 29

Above the alveolar crest in the gingiva.

Question 30

Name the gingival ligament fibres.

Answer 30

Alveolo-gingival:
Connects the gum to bone.

Dento-periosteal:
Connect tooth to the peridontium

Dento-Gingival:
Connects tooth to gum.

Circular:
Supports the free gingiva.

Question 31

Describe the difference in fibre arrangement at the cementum as opposed to the alveolar bone and what is the purpose of this arrangement.

Answer 31

At the cementum the fibres are compact.
At the alveolar bone the fibres are spread/fanned out.

This arrangement allows the high pressure forces applied to the tooth to be dispersed as they are transferred to the alveolar bone.

Question 32

What fibres are composed of collagen in the PDL?

Answer 32

Sharpey fibres.

True periodontal fibres:
Horizontal
Alveolar crest
Oblique 
Apical

Interradicular fibres (found in multi-rooted teeth)

Question 33

What other types of fibres are found in the PDL?

Answer 33

Oxytalan fibres.