(4) Dentino-pulpal Complex - dentin tubules

Question 1

What course do the dentin tubules follow?

Answer 1

Curved sigmoid course

Primary curvature

Question 2

Name structures A and B

Answer 2

Question 3

What type of section is shown here?

Answer 3

Cross section

Partial demineralised section

Question 4

Name structures A-C

Answer 4

Question 5

What side of the dentin is thicker and which is thinner?

Answer 5

The tubules are 2.5μm in diameter at the pulpal end and 1μm or less at the Enamel end.

Question 6

Why do the dentin tubules become closer together at the pulpal end?

Answer 6

As the odontoblasts retreat inwards, they occupy a smaller area, thus the tubules become closer to each others.

Question 7

What cross-sectional area occupies more dentin tubules, enamel-dentin junction or the pulps end?

Answer 7

PULPAL END

22% of the cross sectional area near the pulp is occupied by dentinal tubules.
* 2.5% at the enamel-dentine junction.

Question 8

What does this image show?

Answer 8

Contour lines of Owen

Secondary curvatures, if they coincide in adjacent tubules they give rise to contour lines of Owen (arrowed).

Question 9

Where do dentin tubules branch?

Answer 9

near enamel-dentine junction

Question 10

What happens to terminal dentin-tubules branches at the root?

Answer 10

They loop

Question 11

What forms the wall of the newly formed dentin tubule at the pulp?

Answer 11

Mineralised type 1 collagen

Question 12

What is called intratubular dentin?

Answer 12

Maturation of dentin is associated with the deposition of another type of dentin on the walls

Reduction in the size of lumen, sometimes complete obliteration

Maturation Reduces size of lumen

Question 13

What is the role of the organic dentin phospho-proteins?

Answer 13

Only present in small amounts

Integral in the mineralisation of dentin

Question 14

What are the structural building blocks of dentin?

Answer 14

dentine tubules

Question 15

What is the structure if dentin and its matrix?

Answer 15

formed from parallel tubules arranged in a calcified collagen matrix

Question 16

What is the amelodentinal junction

Answer 16

The point at which the enamel and dentin meet

Question 17

Answer 17

A enamel
B dentin
C dentin tubules ( extend to pulp)

Question 18

What is D

Answer 18

D is the odontoblastic processes

The processes of the cells which form dentin

Question 19

Where do the most prominent contour line of owen occur?

Answer 19

Between primary and secondary dentin

Question 20

Why are the dentine tubules branches?

Answer 20

The odontoblastic processes which form them are branched

Question 21

Where do the terminal dentin tubules loop?

Answer 21

Root

Question 22

Why is the terminal dentin tubule branches layer called?

Answer 22

Granular layer of Tommes

Question 23

Where is the dentine tubules branching found?

Answer 23

Dentin and enamel
Or dentin and cementum

Question 24

What is more mineralised intratubular or intertubular dentin?

Answer 24

Intratubular, 15% more mineralised/ calcified

Question 25

What does intratubular dentin lack?

Answer 25

A collagen matrix

Question 26

What is another name for intratubular dentin?

Answer 26

Peritubular dentin

Question 27

What is the aim protein in peritubular dentin?

Answer 27

Phosphophoryn

Question 28

What is the main inorganic component of peritubular dentin?

Answer 28

Mainly carbonated apatite with a different crystalline structure

Question 29

Peritubular is more mineralised that intertubular dentin, but can it be less calcified?

Answer 29

Yes, some areas are hypocalcified

Question 30

What does physiological ageing of root dentin cause?

Answer 30

Leads to the complete obliteration of tubules with intratubular dentin

Question 31

What happens if you put an aged tooth in water?

Answer 31

Appear translucent when put in water Can see dots through

Question 32

what is the image showing?

Answer 32

Butterfly appearance of the translucent dentin in cross section

Question 33

why does the cross section of the dentin appear butterfly shaped in older age?

Answer 33

Due to the convergence of the tubules Occupy smaller surface area towards the pulp

Question 34

what is found within the dentine tubules?

Answer 34

Odontoblastic processes Afferent nerve terminals APC processes Extracellular dentin fluid Peritubular dentin (lining tubules)

Question 35

what does this image show?

Answer 35

Dentine tubule

Question 36

what do you call the dentin which forms first and where is it formed?

Answer 36

predentin Formed at the pulpal surface

Question 37

is pre-dentin mineralised?

Answer 37

Yes

Question 38

what is found within the dentin tubule?

Answer 38

Odontoblastic process

Question 39

what are the arrows pointing to?

Answer 39

Top, dentine tubule Bottom, odontoblastic process

Question 40

where are the most organelles in the odontoblastc process found and why?

Answer 40

Pre-dentin area Most protein synthesising occurring

Question 41

what organelles are found at the pre-dentine rea?

Answer 41

Mitochondria Protein synthesising organelles

Question 42

where is the odontoblastic process widest and thinnest?

Answer 42

widest at the pulpal end and thinner toward the enamel