Dentine + Pulp

Question 1

Which tissue forms the bulk of the tooth?

Answer 1

Dentine

Question 2

Which tissues of the tooth is dentine harder than/softer than?

Answer 2

Dentine is harder than bone and cementum, but soften than enamel

Question 3

Dentine has greater compressive and tensile strength than enamel. What does this mean?

Answer 3

• Compressive strength: the ability to resist breaking under compression
• Tensile strength: the ability to endure tensile forces without breaking apart

Question 4

Dentine is permeable. What does this mean?

Answer 4

Substances can move through it

Question 5

What is the basic unit of dentine?

Answer 5

Dentinal tubules

Question 6

Describe the content of dentine

Answer 6

• Hydroxyapatite (70% weight, 50% volume)
• Water (10% weight, 20% volume)
• Organic matrix (20% weight, 30% volume)

Question 7

Which contains more organic matrix: enamel or dentine?

Answer 7

Dentine (20% compared to 1-2%)

Organic matrix gives dentine its compressive strength

Question 8

Which direction does mineralisation occur in dentine?

Answer 8

Inwards

Question 9

What is dentine between tubules called?

Answer 9

Intertubular dentine

Question 10

What is intratubular dentine/peritubular dentine?

Answer 10

Dentine created after original tubule becomes smaller

Question 11

What type of curvature is present in dentine?

Answer 11

Primary and secondary curvature

Question 12

What are the boundaries of dentinal tubules?

Answer 12

Tubules run from the amelo-dentine junction to the inner portion of the pulp

Question 13

Which cells form dentine?

Answer 13

Odontoblasts

Question 14

Where are odontoblasts located?

Answer 14

Inside the pulp

Question 15

What is predentine?

Answer 15

• Predentine is an organised matrix that hasn’t been mineralised yet
• Predentine is formed throughout your lifetime

Question 16

Which is formed throughout your lifetime: enamel or dentine?

Answer 16

• Odontoblasts form dentine throughout your lifetime

- Enamel is only formed during embryo stage

Question 17

Which process mineralises dentine?

Answer 17

Nucleation

Question 18

Describe the contents of dentinal tubules

Answer 18

• Odontoblast processes
• Unmyelinated nerve terminals (sensory)
• Dendritic cells (immune cells)
• Dentinal fluid from the pulp

Question 19

How does outer dentine differ from inner dentine?

Answer 19

Outer dentine contains more dentinal fluid. Mineralisation ocurs inwards.

Question 20

Where are outer dentine and inner dentine located?

Answer 20

• Outer dentine: near amelo-dentine junction

- Inner dentine: near pulp

Question 21

What is the dental pulp?

Answer 21

Connective tissue ‘core’ of the tooth

Question 22

Describe the contents of the dental pulp

Answer 22

• Cells: odontoblasts, fibroblasts, defence cells
• Extracellular components: fibres (collagen, oxytalan), matrix (proteoglycans, chondroitin SO4, dermatan SO4)
• Nerves: sensory, autonomic (sympathetic)
• Blood vessels
• Lymphatics

Question 23

What happens to the size of the pulp as we age?

Answer 23

• Less pulp presents, more dentine is formed

- Pulp chamber shrinks

Question 24

What is the ‘cell free zone’?

Answer 24

Space between richly vascularised space and presence of odontoblasts

Question 25

What do odontoblasts act as a barrier between?

Answer 25

The pulp and dentine formation

Blood vessels do not penetrate the odontoblast layer

Question 26

What are the functions of the dental pulp?

Answer 26

• Nutritive, dentine growth, dentine repair, defence (immune cells, lymphatics), neural: sensory, control of dentinogenesis

Question 27

Why doesn’t dentine bleed?

Answer 27

Blood vessels do not penetrate dentine