(4) Dentinal-pulpal complex - dentine variations in structure Flashcards
What is the first layer of dentin to form and the most peripheral?
Mantle dentin
what are the 7 structures in dentin?
What is the width of mantle dentine?
20-150um
what direction does dentin form?
Inwards
does mantle dentin form throughout life?
Yes
Towards the pulp
what is mantle dentin adjacent to?
Enamel
what is the circumpulpal dentin?
All the dentin form the mantle dentin
what is the most mineralised part of dentin?
The circumpulpal dentin
What is more mineralised; mantle or circumpulpal dentine?
Circumpulpal dentine by 5%
what is the direction of the collagen fibres in the mantle dentin?
Perpendicular on the amelo-dentinal junction
Does the mantle dentin have a lot of looping of tubules?
Yes
Because of the branching of the odontoblastic processes at the beginning of the dentine formation
How is mantle dentin mineralised?
Through small vesicles with crystals inside them
what type of section is this?
Ground section
A = enamel
B = mantle dentin
C = circumpulpal dentine (primary curvature)
Arrows = interglobular dentin
what is interglobular dentin?
Area which is hypomineralised and jut under the mantle dentin
Minerals deposited as globules (calcospheres)
how does mineralisation occur in dentin?
globules which fuse together
Fuse to form a uniform calcified tissue
When does interglobular dentin form?
If globules fail to fuse together to form dentin
How does interglobular dentin compare to the rest of the dentin with regard to mineralisation?
just like normal dentin but is not as highly mineralised as threat of the dentin
What passes through the interglobular dentin?
Tubules
why do the interglobular dentin appear dark in a section?
The light passes through them
Interglobular dentin
Where is there lots f branching of the dentinal tubules and what occurs?
In the roots
So much branching creates loops
What happens when loops are formed in the roots? (Section)
Air gets trapped in ground sections and reflect the light and they appear dark
What are the dentinal tubule loops called in the roots?
Granular layer of Tome
Is the granular layer of Tomes hyper or hypomineralised?
hypomineralised
A = acellular cementum
B = granular layer of tomes
C = cementum (granular layer of Tomes)
A = dentin
B = granular layer of tomes
C = hyaline layer
D = acellular cementum
What is the width of the hyaline layer?
Up to 20um
Where do you find the hyaline layer in the tooth?
The root
The crown has mantle dentin
What is the role of the hyaline later?
Helps bonding dentin to cementum
what does the hyaline layer lie outside of?
Granular layer of tomes
What is the structure of circumpulpal dentin?
Uniform in structure except at peripherals
What is predentine?
initially laid dentin matrix prior to mineralisation
how does mineralisation of predentin occur in predentin?
In globules or a linear appearance
What is the width of predentine?
10-40um in width
is predentine thicker in young or older teeth?
Younger
What does the predentin always lie next to?
The pulp
What is mantle dentin always net to?
The enamel
What is the mineralisation front?
The interface between the fully mineralised dentin and newly formed dentin
