Dentine and the Pulp

Question 1

What does the pulp contain?

Answer 1

Blood vessels
Lymphatics
Nerves (autonomic sympathetic)

Question 2

What cells are present in the pulp?

Answer 2

Odontoblasts - produce dentine
Fibroblasts - produce extracellular matrix and collagen.
Defence cells

Question 3

What is the nevre supply to the pulp?

Answer 3

Autonomic sympatetic nevres

Question 4

What are the functions of the pulp?

Answer 4

Dentine growth - primary (whilst tooth is forming) and secondary dentine (once tooth formed)

Dentine repair - tertiary dentine laid down.

Nutritive function- provide blood supply to the tooth.

Defence role - Immune cells present and lymphatics.

Neural - Provides sensory function via autonomic sympathetic nerves.

Question 5

Describe the types of teriary dentine.

Answer 5

Reactionary - laid by primary odontoblasts.

Reparative - laid by secondary odontoblasts
since the stimuli was so intense it destroyed the primary odontoblasts

Question 6

What tissue does dentine and the pulp form from?

Answer 6

Dental papilla.

Question 7

There is a close link between dentine and the pulp; what processes from the pulp etend into the dentine?

Answer 7

Odontoblast processes.
Nerve terminals
Dentinal fluid leaks from the pulpal capillaries into dentinal tubules.

Question 8

What are the functions of the odontoblast layer?

Answer 8

Separates the pulp and tubular space.

Regulate exchange of materials between dentine and the pulp in either direction.

Question 9

What materials are exchanged by the odontoblast layer from the PULP TO DENTINE?

Answer 9

Secondary and tertiary dentine.
K ions from nerve endings - used in AP’s.
Nutrients from the blood supply.

Question 10

What materials are exchanged by the odontoblast layer from the DENTINE TO THE PULP?

Answer 10

Medications applied to the dentine.

Toxins.

Question 11

Where do the pulpal nerves branch from?

Answer 11

The autonomic sympathetic nerves branch from the alveolar nerve.

Question 12

Describe the way in which the nerves enter the pulp.

Answer 12

As neurovascular bundles (nerves and blood vessels joined by connective tissue)

Question 13

Describe the hydrodynamic events that occur after a stimulus has been applied to the tooth.

Answer 13

Stimuli applied.

Increases tubular flow.
Increased flow activates the intra dental nerves via stretching.
Stretching the nerves generates AP’s
Action potentials pass to the brain causing pain.

Question 14

What direction of tubular flow is the most effective in activating intradental nerves?

Answer 14

Outward flow.

Rapid outward flow stretches the nerves and generates pain.

Question 15

What stimuli causes outwards tubular flow?

Answer 15

Cooling and drying.

Question 16

What stimuli causes inward tubular flow?

Answer 16

Heating and mechanical stimuli.

Question 17

What types of autonomic nerve fibres are activated in the hydrodynamic mechanism?

Answer 17

Abeta and Adelta fibres.

Varying degrees of myelination.

Question 18

What stimuli bypasses the hydrodynamic mechanism?

Answer 18

Intense heating and cooling.
Electrical currents
Pain producing chemicals

Question 19

When are C fibres activated within the pulp?

Answer 19

Intense stimuli that acts directly.

Question 20

What nerve fibres mediate pain from pulpal inflammation?

Answer 20

C fibres

Question 21

List the functions of pulpal nerves.

Answer 21

Control blood supply via vessel diameter.
Promote dentine formation.
Mediate pain
Produce neurogenic inflammation.

Question 22

Describe the events that take place in neurogenic inflammation after a stimuli is applied.

Answer 22

Stimuli

Afferent neutron releases inflammatory mediators.
Inflammatory response increases vasodilation of blood vessels.
Increases pulpal pressure
Increases outward tubular fluid flow
= pain.

Question 23

What factors control the blood flow to the pulp?

Answer 23

Sympathetic, somatic nerves.

Local metabolites.

Circulating hormone e.g. adrenaline

Drugs e.g. Local anaesthetic with vasoconstrictors.

Question 24

Describe the dentine-pulp response to injury over 1 week.

Answer 24

Immediate repose:
Nociceptor activation.

1 minute:
Early inflammatory response = vasodilation of blood vessels.

10 minutes:
Nociceptor sensitisation and oedema.

100 minutes:
Enzyme activates nerve growth factor.

1 day:
Nerve sprouting occurs to replace the damaged axons.

1 week:
Repair via tertiary dentine.

Question 25

What is pulpits and why is it so painful?

Answer 25

Acute inflammation of the pulp.

Swelling is restricted by the tooth crown therefore nerve excitability and blood flow is effected.