(4) Dentino-pulpal Complex - dentin tubules Flashcards
What course do the dentin tubules follow?
Curved sigmoid course
Primary curvature
Name structures A and B
What type of section is shown here?
Cross section
Partial demineralised section
Name structures A-C
What side of the dentin is thicker and which is thinner?
The tubules are 2.5μm in diameter at the pulpal end and 1μm or less at the Enamel end.
Why do the dentin tubules become closer together at the pulpal end?
As the odontoblasts retreat inwards, they occupy a smaller area, thus the tubules become closer to each others.
What cross-sectional area occupies more dentin tubules, enamel-dentin junction or the pulps end?
PULPAL END
22% of the cross sectional area near the pulp is occupied by dentinal tubules.
* 2.5% at the enamel-dentine junction.
What does this image show?
Contour lines of Owen
Secondary curvatures, if they coincide in adjacent tubules they give rise to contour lines of Owen (arrowed).
Where do dentin tubules branch?
near enamel-dentine junction
What happens to terminal dentin-tubules branches at the root?
They loop
What forms the wall of the newly formed dentin tubule at the pulp?
Mineralised type 1 collagen
What is called intratubular dentin?
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
What is the role of the organic dentin phospho-proteins?
Only present in small amounts
Integral in the mineralisation of dentin
What are the structural building blocks of dentin?
dentine tubules
What is the structure if dentin and its matrix?
formed from parallel tubules arranged in a calcified collagen matrix
What is the amelodentinal junction
The point at which the enamel and dentin meet
A enamel
B dentin
C dentin tubules ( extend to pulp)
What is D
D is the odontoblastic processes
The processes of the cells which form dentin
Where do the most prominent contour line of owen occur?
Between primary and secondary dentin
Why are the dentine tubules branches?
The odontoblastic processes which form them are branched
Where do the terminal dentin tubules loop?
Root
Why is the terminal dentin tubule branches layer called?
Granular layer of Tommes
Where is the dentine tubules branching found?
Dentin and enamel
Or dentin and cementum
What is more mineralised intratubular or intertubular dentin?
Intratubular, 15% more mineralised/ calcified
What does intratubular dentin lack?
A collagen matrix
What is another name for intratubular dentin?
Peritubular dentin
What is the aim protein in peritubular dentin?
Phosphophoryn
What is the main inorganic component of peritubular dentin?
Mainly carbonated apatite with a different crystalline structure
Peritubular is more mineralised that intertubular dentin, but can it be less calcified?
Yes, some areas are hypocalcified
What does physiological ageing of root dentin cause?
Leads to the complete obliteration of tubules with intratubular dentin
What happens if you put an aged tooth in water?
Appear translucent when put in water
Can see dots through
what is the image showing?
Butterfly appearance of the translucent dentin in cross section
why does the cross section of the dentin appear butterfly shaped in older age?
Due to the convergence of the tubules
Occupy smaller surface area towards the pulp
what is found within the dentine tubules?
Odontoblastic processes
Afferent nerve terminals
APC processes
Extracellular dentin fluid
Peritubular dentin (lining tubules)
what does this image show?
Dentine tubule
what do you call the dentin which forms first and where is it formed?
predentin
Formed at the pulpal surface
is pre-dentin mineralised?
Yes
what is found within the dentin tubule?
Odontoblastic process
what are the arrows pointing to?
Top, dentine tubule
Bottom, odontoblastic process
where are the most organelles in the odontoblastc process found and why?
Pre-dentin area
Most protein synthesising occurring
what organelles are found at the pre-dentine rea?
Mitochondria
Protein synthesising organelles
where is the odontoblastic process widest and thinnest?
widest at the pulpal end and thinner toward the enamel
