Physiology of the Pulp

Question 1

Describe the basic physiological features of a tooth

Answer 1

• Enamel as the outermost layer
• Dentine comes next
• Pulp comes next
• PDL and periodontal membrane present outside root dentine
• Cementum attaches PDL to dentine

Question 2

Describe 4 features of the form of dental pulp

Answer 2

1. Loose connective tissue in tooth
2. Made up of combination of cells in ECM of fibres
3. Enclosed by dentine except at apex where continuous with PDL
4. Relatively small volume in tooth

Question 3

Name 3 functions of the dental pulp

Answer 3

1. Maintain health of dentine by providing nutrients
2. Provides pathway for sensory impulses
3. Initiates and controls repair of dentine when damaged

Question 4

What 2 things make up the pulp?

Answer 4

1. ECM / Ground substance

2. Cells

Question 5

What part of the pulp is responsible for the water-holding properties?

Answer 5

ECM

Question 6

Name 3 types of glycoproteins in the dental pulp

Answer 6

1. Proteoglycans
2. Glycosaminoglycans (GAGs)
3. Fibronectin

Question 7

What are proteoglycans?

Answer 7

Consist of a core of proteins surrounded by GAGs

Question 8

What are GAGs?

Answer 8

Long chain carbohydrate molecules which retain water to form a gel

Question 9

What is the role of fibronectin?

Answer 9

Major role as an anchor protein

Question 10

What are 2 types of structural proteins found in the pulp?

Answer 10

1. Collagen

2. Elastin

Question 11

Describe collagen as a component of the pulp

Answer 11

Makes up around 1/3 of dry weight of pulp and confers structure to tissue by maintaining position of vessels, nerves and cells

Question 12

Describe elastin as a components of the pulp

Answer 12

Present only in the walls of blood vessels of the dental pulp

Question 13

Name 4 types of cells found in the pulp

Answer 13

1. Odontoblasts
2. Fibroblasts
3. Defence cells
4. Stem cells

Question 14

Describe odontoblasts found in the pulp

Answer 14

• Form outermost stratum of cells in healthy pulp
• Most highly differentiated cells of pulp
• Produce components of predentine and dentine including collagen
• Series of specialised junctions between adjacent odontoblasts

Question 15

Describe 2 components of the ultrastructure of mature odontoblasts in the pulp

Answer 15

1. Cytoplasmic process which extends into dentinal tubule

2. Smaller processes link odontoblast with neighbouring odontoblasts and fibroblasts

Question 16

Describe fibroblasts found in the dental pulp

Answer 16

• Most numerous cell type found
• Produce gelatinous matrix in which all components are embedded
• Produce collagen fibres which reinforce ECM
• Produce MMPs which degrade collagen and proteoglycans

Question 17

Name 4 defence cells of the pulp

Answer 17

1. Macrophages
2. Dendritic cells
3. T-lymphocytes
4. Mast cells

Question 18

Describe the location and function of macrophages in the dental pulp

Answer 18

• Found around blood vessels of inner pulp and odontoblast layer
• Phagocytose dead cells and foreign bodies

Question 19

Describe the location and function of dendritic cells in the dental pulp

Answer 19

• Subjacent to the odontoblast layer in perivascular regions

- Monitor invasion of antigens

Question 20

Describe the volume o T-lymphocytes in the dental pulp

Answer 20

Present in small numbers but increase when pulp is injured or exposed to noxious stimuli

Question 21

Describe when mast cells are routinely seen in pulp

Answer 21

Routinely found in chronically inflamed pulp

Question 22

Where are stem cells found in the pulp?

Answer 22

Along capillaries in cell rich zone and to a lesser extent throughout the pulp

Question 23

Describe the pulpal vasculature

Answer 23

• Arterioles and venules enter dental pulp in neurovascular bundle via apical foramen
• Divide and narrow to some degree in root canals
• Branch profusely in coronal pulp

Question 24

Name a unique feature of the pulp with regards to expansion

Answer 24

It is rigidly encased within the dentine which is a low compliance environment with limited ability to extend

Question 25

Describe how the pulp is innervated

Answer 25

- Sensory nerves arise from trigeminal nerve - Pass into radicular pulp via apical foramen - Closely associated with blood vessels

Question 26

In what form do nerves enter the apical foramen?

Answer 26

Bundles

Question 27

Name 2 types of nerves found in the pulp

Answer 27

1. A-fibres (myelinated) | 2. C-fibres (unmyelinated)

Question 28

What are 2 types of A-fibres found in the pulp?

Answer 28

1. Aβ | 2. Aδ

Question 29

What type of sensation is conveyed by A-fibres?

Answer 29

Sharp, penetrating, short lasting sensations

Question 30

Name 3 things which activate myelinated nerves in the pulp

Answer 30

1. Air (Aδ) 2. Hot / Cold (Aδ) 3. Vibration (Aβ)

Question 31

Where are A-fibres found in the pulp?

Answer 31

Abundant at the pulp-dentine junction

Question 32

Where are C-fibres found in the pulp?

Answer 32

Abundant in the pulp proper

Question 33

Name 3 things which activate C-fibres in the pulp

Answer 33

1. Inflammatory mediators 2. Mechanical deformation 3. Heat

Question 34

Describe 3 differences between dentinal and pulpal pain

Answer 34

1. Dentinal pain consequence of external stimulus whereas pulpal pain is usually inflammatory in origin 2. Dentinal pain brief and sharp whereas pulpal pain has prolonged time course 3. Dentinal pain arises as a result of A-fibre activation whereas pulpal pain arises as a result of C-fibre activation

Question 35

How are dentinal tubules related to dentinal pain?

Answer 35

Dental pain involves fluid movement in the dentinal tubules

Question 36

Describe the lumen of the dentinal tubules, especially with regards to enamel junction and pulpal junction

Answer 36

- Inverted cone shape - Lumen narrow at the enamel junction due to present of peritubular dentine - Lack of peritubular dentine at pulpal boarder so tubules are wider here

Question 37

Describe the morphological zones of pulpodentine complex from the outside in

Answer 37

- Dentine - Odontoblast layer - Cell free zone - Cell rich zone - Pulp proper

Question 38

Name 2 reasons the pulp decreases in size with age

Answer 38

1. Deposition of secondary dentine throughout life | 2. Development of tertiary dentine in response to caries

Question 39

Describe repair of the pulp, including how this changes with age

Answer 39

- Local circulation critical to healing - Highly cellular young pulp much better healing potential than older tooth - Reparative dentine deposited at sites of irritation - Dentine becomes inert when pulp removed or necrotic