Dentine and pulp

Question 1

What is dentine

Answer 1

-Forms bulk of tooth​
-Harder than bone and cementum, but softer than enamel​
-Greater compressive and tensile strength compared with enamel​
-Permeable: contains tubules​
-Contains cell processes​
-Yellowish in colour (‘ivory’)​

Question 2

What is compressive strength

Answer 2

Ability to withhold force and return to original strength

Question 3

Content of dentine

Answer 3

Hydroxyapatite (HA) ​
-70% weight (50% volume)​

Water ​(dry tooth is more fragile)
-10% weight (20% volume)​

Organic matrix ​
-20% weight; (30% volume)​

Question 4

Is enamel permeable

Answer 4

No only dentine

Question 5

Tubules within the dentine
-structures

Answer 5

Original tubule outline
Peritubular/Intratubular dentine
Intertubular dentine

Question 6

What is found within dentinal tubules

Answer 6

-Odontoblast process​
-Unmyelinated nerve terminals (sensory)​
-Dendritic cells (immune system)​
-‘dentinal fluid’ or extracellular fluid from pulp​

Question 7

What is dental pulp and what does it contain

Answer 7

Connective tissue ‘core’ of tooth​

Cells:​
Odontoblasts, fibroblasts, defence cells​

Extracellular components​
-Fibres (collagen, oxytalan)​
-Matrix (proteoglycans, chondroitin SO4, dermatan SO4)​

Nerves​
-Sensory; autonomic (sympathetic)​

Blood vessels​

Lymphatics​

Question 8

What is the function of odontoblasts

Answer 8

Cell that produces predentine within the pulp

Question 9

What forms dentine

Answer 9

the matrix produced by odontoblasts (predentine) is then mineralised to form dentine

Question 10

Functions of dental pulp

Answer 10

-Nutritive ​
-Dentine growth​
-Dentine repair​
-Defence​:
Immune cells; lymphatics ​
-Neural​:
Sensory ​
Control of dentinogenesis​

Question 11

What are proteoglycans

Answer 11

Proteins bound to mucopolysaccharides (present in connective tissue)
Proteins that have sugar (carbohydrate)

Question 12

What is the inflammatory response of tissue when damaged

Answer 12

swelling
redness
pain
heat
pressure builds due to swell impacting the blood vessels which are responsible for delivering nutrients to cells which starve and die

Question 13

A few tubules may contain dendritic cells (part of the immune system). Are the processes from odontoblasts, nerves and dendritic cells found all the way along the dentinal tubules?

Answer 13

No

Question 14

Where are dentinal tubules larger

Answer 14

Inner dentine

Question 15

What is the function of tertiary dentine

Answer 15

Protective - lies closest to the pulp

Question 16

Which dentine is more permeable, closer to pulp/closer to enamel

Answer 16

The dentine closer to the pulp as the interconnection is poorer due to the larger tubules

Question 17

When is primary dentine produced

Answer 17

When tooth is yet to be completely formed

Question 18

What is the difference between primary and secondary dentine

Answer 18

rate of production is considerably slower in secondary dentine

Question 19

Does tertiary dentine have dentinal tubules

Answer 19

No

Question 20

difference between reactionary / reparative dentine

Answer 20

Difference - odontoblasts produce reactionary dentine as it sees the risk for injury and wants to fill the space

If odontoblasts die stem cells can become odontoblasts and these odontoblasts form tertiary dentine (reparative)
Tertiary dentine takes much longer to form as the stem cells must be recruited