Dentine Microstructure

Question 1

Dentinal tubules morphology:
Where do dentinal tubules run from and to

Answer 1

From the pulpal surface to the ADJ interface

Question 2

Dentinal tubules morphology:
What is dentine location between tubules called

Answer 2

Intertubular dentine

Question 3

Dentinal tubules morphology:
Where is peritubular dentine deposited with maturation

Answer 3

On the walls of the dentine tubules, narrowing their lumens

Question 4

Dentinal tubules morphology:
Describe primary curvatures

Answer 4

• Describe the S shaped path dentine tubules follow
• As tubules progress down the root, the curvature is much less pronounced

Question 5

Dentinal tubules morphology:
Describe secondary curvatures

Answer 5

Small, regular wave-like deviations in the path of dentine tubules

Question 6

Where is the branching of dentinal tubules most noticable

Answer 6

Near the ADJ, immediately under the enamel in the tooth crown

Question 7

Dentinal tubules morphology:
In the root, the terminal part of tubules branch and the branches loop, what may this looping be responsible for?

Answer 7

The apperance of the granular layer of Tomes beneath the CEJ in the root

Question 8

Dentinal tubules regional variation:
Where may dentinal tubules be wider

Answer 8

Wider at the pulpal end

Question 9

Dentinal tubules regional variation:
What is the relation between peritubular dentine and following a tubual from its pulpal end to its periphal end

Answer 9

More peritubual dentine in found on its walls, gradually decreasing the diameter of the tubual’s lumen

Question 10

Dentinal tubules regional variation:
Where are dentinal tubules more widely seperated and tightly packed
Why is this the case

Answer 10

• More widely seperated at their peripheries near the ADJ and more tightly packed near the pulp
• This is because the outer surface area of dentine at the ADJ is larger than the inner pulpal surface area whilst the number of tubules at the 2 positions remains the same

Question 11

Dentinal tubules regional variation:
Where do odontoblasts migrate and where do they occupy

Answer 11

• Migrate inwards
• Occupy a small surface area (become more crowded) as dentinogenesis progresses towards the pulp

Question 12

Peritubular dentine:
What is the difference between peritubular dentine and intertubular dentine?

Answer 12

Peritubular dentine lacks a collagen fibrillar matrix

Question 13

Peritubular dentine:
What does peritubular dentine consist of?

Answer 13

Consists of small crystals in a non-fibrillar matrix consisting of:
- Proteoglycans
- Glycoproteins
- Osteonectin
- Osteocalcin
- Bone sialoproteins
- Lipids

Question 14

Peritubular dentine:
What is the mineral component of peritubular dentine mainly

Answer 14

Mainly carbonated apatite

Question 15

Peritubular dentine:
In older teeth, where is peritubular dentine formation?

Answer 15

Usually found near the root apices

Question 16

Peritubular dentine:
Describe the relation between peritubular dentine formation and intertubular dentine formation

Answer 16

• Formation occurs around the same time
• By the time primary dentine formation is complete, all peripheral tubules have a lining of peritubular dentine that extends from the ADJ to the mineralisation front

Question 17

Peritubular dentine:
Where is dentine first formed

Answer 17

Near the ADJ

Question 18

Peritubular dentine:
What percentage of peritubular dentine occupies the cross-sectional area in the dentine near the ADJ

Answer 18

66% (two thirds)

Question 19

Peritubular dentine:
What percentage of peritubular dentine occupies the cross-sectional area near the predentine

Answer 19

3%

Question 20

Dentinal tubules content:
What do dentinal tubules contain

Answer 20

• Long processes of odontoblasts
• There are responsible for the formation + maintenance of dentine

Question 21

Dentinal tubules content:
Where are cell bodies of the odontoblasts found?

Answer 21

At the pulpal end of the tubules, lining the walls of the pulp

Question 22

Dentinal tubules content:
What may also be found at the inner part of dentinal tubules

Answer 22

• Antigen-presenting cell processes from peripheral pulp
• Afferent sensory nerve axons

Question 23

Dentinal tubules content:
What is the space around + beyond an odontoblast process thought to be filled with
What occurs if dentine is cut?

Answer 23

• Dentinal fluid
• Fluid is dicharged from tubules + the dentine surface remains wet

Question 24

Dentinal tubules content:
Where do the odontoblast processes occupy when dentine is in the early stages of development?

Answer 24

Occupy the full width of the dentinal tubule

Question 25

Dentinal tubules content:
What happes to the number of tubules occupied by odontoblasts seen as we move to outer dentine

Answer 25

The number of tubules occupied by odontoblasts decreases

Question 26

Dentinal tubules content:
What happens when the odontoblast process reaches a predetermined length

Answer 26

The odontoblast process moves towards the pulp, along with the odontoblast cell body, leaving behind an empty tubule in which peritubular dentine has formed