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Flashcards in Dentin Deck (34)
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1

What do the tubules in dentin contain

- odontoblastic processes
- dentinal fluid
- nerve endings

2

What stage of tooth formation does dentin formation begin

Bell stage

3

What colour is dentin, is it permeable/impermeabe

Dentin = pale yellow in colour and permeable

4

Is dentin harder/softer than bone, cementum and enamel

Harder than bone and cementum but softer than enamel

5

Describe the chemical structure of dentin

Calcium hydroxyapatite crystals are found between type 1 collagen fibrils, the crystals are much smaller than those in enamel

6

What shape do the dentinal tubules make and why

S shapes
due to the crowding of odontoblasts as they get squeezed into a smaller and smaller space within the pulp cavity, known as the primary curve

7

What are the contour lines of owen and how do they form

These are the appearance of a line crossing the dentin and are caused by subtle changes in direction during dentin depositions that creates wavy dentinal tubules, these are known as the secondary curves.

8

Where are the secondary curves of dentin normally found

Usually found at the junction of primary and secondary dentin

9

How might dentinal tubules appear differently in the periphery near the DEJ

They branch profusely, many small side branches, some may unite with branches of other tubules

10

What is the purpose of the lateral branches (Canaliculi) of dentinal tubules

This is where odontoblastic processes can communicate with one another

11

What is intra/peritubular dentin and what is interlobular dentin

Peri = dentin that forms the wall of each tubule, more mineral that interlobular dentin
Inter = Dentin between tubules

12

Does peri or interlobular dentin have more collagen

Inter

13

Is peri or inter dentin more mineralised

Peri

14

How are the type 1 collagen fibres arranged in inter dentin

Arranged perpendicular to the tubule

15

What is the circumpulpal dentine and describe its structure(s)

Forms the bulk of the dentin
Uniform in structure except
- Outer surface - interlobular
- inner surface - mineralisation front

16

How might the tubules of circumpulpal dentin be modified

Modified with age by secondary dentin deposition in pulp
Modified by disease by tertiary dentin

17

Where are the hyaline and granular layers of the dentin

These are found in the periphery of the root

18

Describe the dentin and dentinal tubules found in the Hyaline and granular layers of the dentin

- Hypo-mineralised in comparison to circumpupal dentin
- Dentinal tubules branch more profusely and loop back creating air spaces

19

Where is interglobular dentin found

Found just below the mantle zone in the crown or granular layer of tomes in the root.

20

Describe the features of the interglobular dentin and dentinal tubules

It is less calcified and appears as irregularly shaped crescents
Tubules pass through but peritubular dentin is absent in these areas

21

Why is interglobular dentin less calcified

Results from uneven fusion of the mineralisation front

22

What is the prevention

• Initially laid down dentine matrix before
mineralization
• The innermost layer of the dentine
• The mineralising front-globular or linear

23

How does mineralisation occur in dentin

• Organic matrix laid down by odontoblasts
• Calcium transported through odontoblast to area of calcification
• Calcium becomes crystalline in dentine after deposition onto collagen fibrils
• As matrix deposition and mineralisation continue,
a zone of calcification will nearly always be visible

24

What is linear and globular mineralisation of dentin

• Linear – deposition by apposition onto existing calcified areas
• Globular – deposition occurs in spheres (calcospherites)

25

How does globular calcification of dentin happen

Begins in small spherical areas that become larger and fuse with one another to form a calcification front.

26

What are von Ebner lines

Incremental lines associated with matrix deposition and mineralisation
• Daily alterations in the formation of dentine
• Seen as banding along the dentinal tubules
• Perpendiculartothedentinaltubules.

27

What happens to primary dentin with age

Can become translucent with age (increased deposition of peritubular dentine occludes tubule)

28

When does secondary dentin deposition occur

begins after eruption - often as tooth comes into occlusion.

In time will reduce pulp chamber and root canal size

29

What is the structural difference between primary and secondary dentin

Structurally similar to primary dentine but with fewer tubules

30

When is tertiary dentin produced and what is its role

Produced in response to external stimuli (attrition, caries, cavity preparation, trauma).
It has a protective role