Dentine and Pulp

Question 1

What unit makes up dentine?

Answer 1

Dentine tubules.

Question 2

What is dentine?

Answer 2

Forms the bulk of tooth.
Harder than cementum and bone but softer than enamel.
Greater compressive and tensile strength compared to enamel.

Question 3

What is the significance of dentine tubules?

Answer 3

Dentine and porous and permeable.
If you apply a chemical to one side of dentine, it will go through the other side of dentine and into the pulp.

Question 4

What makes up the bulk of dentine?

Answer 4

50% hydroxyapatite
20% water
30% organic matrix

Question 5

Where does dentine extend to?

Answer 5

Extends from the ADJ to the pulp.

Question 6

Describe the contents of dentinal tubules?

Answer 6

Odontoblast processes
Unmyelinated nerve terminals
Dendritic cells
Dentinal fluid or extracellular fluid from pulp

Question 7

Describe the communication between dentine and the pulp?

Answer 7

Odontoblasts are in the pulp (cells that make dentine) but they extend their processes into dentine, there are also nerve terminals, immune cells and dentinal fluid that communicate between the two.
Anything that influences dentine, will also be influencing the pulp.

Dentine and pulp both originate from the dental papilla.

Question 8

Describe the location of odontoblasts, predestine and dentine?

Answer 8

Pulp (odontoblasts), predestine and then dentine.

Question 9

Describe the differences between inner dentine and outer dentine?

Answer 9

Outer dentine has been made a long time ago, nearer the ADJ. It has intratubular dentine.

Inner dentine was made more recently, no intratubular dentine.

Question 10

What is the dental pulp?

Answer 10

Connective tissue core of the tooth.

Question 11

Describe the contents of the dental pulp?

Answer 11

Cells- odontoblasts, fibroblasts, defence cells
Collagen
Matrix- proteoglycans
Nerves
Blood vessels
Lymphatics

Question 12

Why does the pulp regress with age?

Answer 12

More dentine is made as you get older and the pulp naturally regresses
- need to bear this in mind when looking at pulp chambers of an older patient.

Question 13

Describe the function of the dental pulp?

Answer 13

Nutritive
Dentine growth
Dentine repair
Defence- immune cells and lymphatics
Neural- sensory

Question 14

Why is tertiary dentine laid down?

Answer 14

When the tooth comes under insult, specifically when the odontoblasts become damaged, to try protect the pulp.
Acts as a plug to seal the tubules off at the pulp.

Question 15

Describe the difference between reactionary and reparative dentine.

Answer 15

Reactionary- in response to a mild stimulus, tertiary dentine is laid down my primary odontoblasts.

Reparative- in response to intense stimulus that destroys the primary odontoblasts.
Laid down by secondary odontoblasts, which are sub-odontoblastic stem cells.

Question 16

Describe the difference between primary and secondary dentine?

Answer 16

Primary dentine is laid down prior to eruption of the tooth.
Secondary dentine is laid down in the pulp and is gradually made throughout life, post eruption.

Question 17

How do blood vessels and nerve enter the pulp?

Answer 17

Through the apical foramen, at the apex of the root.

Question 18

Describe the response of dentine and the pulp to a traumatic injury?

Answer 18

Immediate- nociceptor activation, patient feels pain.
After 1 minute- early inflammatory response, vasodilation.
After 10 minutes- nociceptor sensitisation, oedema.
After 100 minutes- enzyme activation, nerve growth factor.
After 1 day- nerve sprouting, increased axonal transport, altered excitability of CNS synapses.
After approx 1 week- Repair, tertiary dentine formation.