Periodontium

Question 1

Name functions of the periodontium (3)

Answer 1

1. Retains tooth in socket
2. Resists masticatory loads
3. Defensive barrier: protecting tissues against threats from the oral environment

Question 2

What is the junctional epithelium

Answer 2

The physical barrier separating the body tissues from the oral environment

Question 3

How is periodontal disease classified? (2)

Answer 3

1. Diseases of the gingiva alone

2. Diseases of all periodontal tissues

Question 4

Name the periodontal tissues (4)

Answer 4

1. Cementum
2. Alveolar bone
3. Gingiva
4. Periodontal ligament

Question 5

Functions of cementum (2)

Answer 5

1. Covers root dentine

2. Provides attachment for some periodontal fibres

Question 6

Structure of cementum?

Answer 6

• Collagen matrix

- Lamellar arrangement

Question 7

What cells produce cementum?

Answer 7

Cementum is laid down by cementocytes

Question 8

Name the 2 types of cementum

Answer 8

1. Acellular cementum

2. Cellular cementum

Question 9

State 3 properties of acellular cementum

Answer 9

1. No cells within
2. Usually adjacent to dentine
3. First formed (primary cementum)

Question 10

State 3 properties of cellular cementum

Answer 10

1. Contains cementocytes
2. Later formed (secondary cementum)
3. Present in apical part of root and in furcation regions

Question 11

What type of cementum contains sharpey’s fibres?

Answer 11

Acellular extrinsic fibre cementum

Question 12

What type of cementum does NOT contain sharpey’s fibres?

Answer 12

Cellular intrinsic fibre cementum

Question 13

Location of acellular extrinsic fibre cementum?

Answer 13

Present on the cervical 2/3rd of roots

Question 14

Function of cellular intrinsic fibre cementum?

Answer 14

• No role in tooth attachment

- May represent a transitional form

Question 15

What type of cementum is better at regeneration?

Answer 15

Acellular

- As it provides anchorage so its better at regeneration

Question 16

Why is cellular intrinsic fibre cementum less successful at treating perio disease?

Answer 16

Lack of sharpey’s fibres

Question 17

Formation of the alveolar bone

Answer 17

• Cortical plate forms the inner lining of the tooth socket

Question 18

Function of the alveolar bone

Answer 18

• Provides attachment for periodontal ligament fibres (sharpens fibres)
• Alveolar bone support the teeth
• penetrated by nutrient canals (Volkmanns)

Question 19

In terms of the alveolar bone, what happens when teeth are lost?

Answer 19

The alveolar process is resorbed, leaving a residual ridge

Question 20

What is contained within the periodontal ligament? (5)

Answer 20

1. Cells
2. Extracellular matrix
3. Fibres
4. Nerves
5. Blood vessels

Question 21

What makes up the PDL matrix (ground substance?) (3)

Answer 21

1. Hyaluronate GAGs
2. Glycoproteins
3. Proteoglycans

behave as a viscoelastic gel (capacity to return to original shape)

Question 22

What cells are present in the PDL? (5)

Answer 22

1. Fibroblasts
2. Cementoblasts
3. Osteoclasts/cementoclasts
4. Epithelial cells
   - Debris of malassez
5. Defence cells

Question 23

What nerves are present in the PDL (2)

Answer 23

1. Sensory

2. Autonomic (sympathetic)

Question 24

Function of sensory nerves in the PDL (2)

Answer 24

Mechanoreceptors (AB + A delta fibres)
- Proprioception; chewing control

Nociceptors (A delta + C fibres)

• Protective reflexes
• inhibit jaw elevator motor neurons

Question 25

Function of the autonomic nerves in the PDL

Answer 25

Blood vessel control - vasoconstriction

Question 26

What type of fibres are myelinated?

Answer 26

Fibres

Question 27

Function of adrenaline in LA?

Answer 27

Adrenaline in LA reduces blood flow and reduces clearance

Question 28

What is the blood supply for the PDL? (2)

Answer 28

1. From inferior and superior alveolar arteries - Passing into the PDL from the alveolar bone 2. From lingual and palatine arteries - Supplying the gingivae

Question 29

What are the types of periodontal LIGAMENTS present in the PDL? (2)

Answer 29

1. True periodontal ligament - Fibres connecting the tooth to bone at or apical to the alveolar crest 2. Gingival ligament - Mainly above the alveolar crest, including 'free gingival' fibres

Question 30

State functions of the periodontal ligament (3)

Answer 30

1. Attaches the tooth to the jaw 2. Transmits biting forces to the alveolar bone 3. Organised (regular) connective tissue

Question 31

State the width of the PDL

Answer 31

Approx 0.2mm

Question 32

What are the types of periodontal FIBRES present in the PDL? (3)

Answer 32

1. Collagen (Types I and III) > Principal fibres - true periodontal ligament > Supports tooth; load-bearing 2. Oxytalan fibres > Present in human PDL > Function uncertain 3. Elastic fibres > Absent in humans

Question 33

What are the PDL principal fibre groups, and what are they made up of? (2)

Answer 33

Alveolo-dental ligament 1. Alveolar crest 2. Horizontal 3. Oblique 4. Apical 5. Interradicular (multi-rooted teeth) Interdental ligament 1. Transseptal fibres

Question 34

State the function of oblique fibres in the PDL

Answer 34

Rotational activity of the tooth

Question 35

State the function of apical fibres in the PDL

Answer 35

Coil that receives the forces

Question 36

Function of the gingival fibre group in PDL

Answer 36

Supports the free gingivae

Question 37

Where is the gingival fibre group found?

Answer 37

Present in the lamina propria in the marginal gingiva: > Dento-gingival > Alveolo-gingival > Dento-periosteal > Circular

Question 38

Compare free + attached gingivae

Answer 38

Free: Gingivae that is not attached to bone Attached Gingivae that is attached to bone

Question 39

Function of the free gingival groove?

Answer 39

Separates the free and attached gingiva

Question 40

Name examples of intrusive forces that the PDL may be exposed to (4)

Answer 40

1. Mastication 2. Swallowing 3. Speech 4. Parafunction (e.g. clenching/grinding)

Question 41

Name examples of RARE extrusive forces that the PDL may be exposed to (2)

Answer 41

1. Sticky foods | 2. Orthodontic forces

Question 42

What are the effects of loading on a tooth? (4)

Answer 42

1. Initial elastic component 2. Later viscous 'creep' 3. Tension in PDL fibres 4. Compression of ECF