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OCB02 > OCB02-1016 Dentine > Flashcards

OCB02-1016 Dentine Flashcards

1
Q

What is responsible for the yellow colour of the tooth?

A

Dentine

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2
Q

What is dentin perforated by?

A

Tubules

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3
Q

What are tubules?

A

They go from the pulp to EDJ and carry fluid from the pulp

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4
Q

What % of dentine is inorganic?

A

70%

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5
Q

What % of dentine is organic ?

A

20%

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6
Q

What % of the organic dentine is type I collagen?

A

90%

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7
Q

What % of the organic dentine is non collagenous proteins?

A

8%

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8
Q

What % of the organic dentine are lipids?

A

2%

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9
Q

What % of dentine is water?

A

10%

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10
Q

How does the hydrophobic composite filing pose a problem?

A

fluid flow creates a wet environment around the oral cavity

The outward fluid flow limits the penetration of bonding agents

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11
Q

What are the two types of dentine?

A

coronal and radicular dentine

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12
Q

What are the two types of coronal dentine?

A

Mantle dentine and circumpulpal dentine

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13
Q

What is mantle dentine?

A

The outermost layer of dentine that lies just below the enamel

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14
Q

What is circumpulpal dentine?

A

Circumpulpal dentine lies below the mantle dentine and extends round the crown and down into the root

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15
Q

What is the difference between mantle and circumpulpal dentine?

A

Mantle dentine is slightly less mineralised and more porous than circumpulpal dentine

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16
Q

What are the two types of radicular dentine?

A

Hyaline layer of Hopewell Smith

Granular layer of Tomes

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17
Q

What is the hyaline layer of Hopewell Smith?

A

Next to the cementum and has no dentinal tubules

May serve to bond the cementum to the dentine and is the last dentine layer to mineralise

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18
Q

What is the granular layer of Tomes?

A

Beneath the hyaline layer
Its less mineralised than the circumpulpal layer
Collagen fibres run parallel to the root surface

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19
Q

What pattern does the primary curvature of the tubules follow from the EDJ?

A

A sigmoidal S-shaped pattern due to overcrowding of odontoblasts

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20
Q

When is the secondary curvature of the dentinal tubules formed?

A

The tubules change direction every few micrometer

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21
Q

What layer of dentine are the branching and loops of the dentinal tubules responsible for?

A

Granular layer of Tomes in root dentine

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22
Q

What is the odontoblast process responsible for?

A

Secretion of hydroxyapatite crystals and mineralisation of the matrix

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23
Q

Where is peritubular space not present with dentinal tubules?

A

Predentine level or innermost mineralised dentine

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24
Q

What is another word for peritubular dentin?

A

Intratubular dentine

25
Q

What is the peritubular space filled with?

A

Dentinal fluid which exerts a positive outwards pressure

26
Q

What does peritubular dentin do?

A

It creates the wall of the dentinal tubules

27
Q

How does the growth of pertiubular dentine affect the diameter of the dentinal tubules?

A

As the peritubular dentine grows, it reduces the size of the dental tubules

28
Q

How does the amount of peritubular dentine change with age?

A

It increases and eventually occludes the tube

29
Q

What is the difference between peritubular and interlobular dentine?

A

Peritubular dentine is hyper calcified compared to interlobular

30
Q

Where about are the diameter and density of the tubules the greatest?

A

Near the pulp

31
Q

What is the purpose of etching?

A

To remove the smear layer of microcrystalline and organic particle debris on root canal walls to prevent bacteria entering the dentinal tubules

32
Q

What are von-ebner lines?

A

Visible as light-dark band patterns that run perpendicular to dentinal tubules

33
Q

Where are von-ebner lines present?

A

Circumpulpal dentine

34
Q

What conditions can Andersen lines be seen?

A

Under polarised light

35
Q

What slows the development of Andersen lines?

A

Birth or death

36
Q

Where is the neonatal line seen?

A

All primary teeth and permanent molars

37
Q

How does the neonatal line differ from other Retzius lines?

A

It is darker and larger

38
Q

What does the initial matrix become?

A

Mantle dentin

39
Q

What are the collagen fibres in the mantle dentin that are perpendicular to IEE called?

A

Von Korff Fibres

40
Q

What is unmineralised dentine called?

A

Predentine

41
Q

What staining appearance does predentine have?

A

Pale

42
Q

What is the area between predentine and mineralised dentine called?

A

Metadentine

43
Q

What are circular areas of mineralisation called?

A

Calcospherites

44
Q

What is interglobuar dentine?

A

Areas that haven’t been fully calcified and only primary mineralisation has occurred in the predentine
Formed by the failure of calcospherites to fuse

45
Q

Where is interlobular dentine located?

A

Below the mantle dentin the the granular layer

46
Q

When is secondary dentin formed?

A

Formed after root formation is complete, after the tooth has erupted

47
Q

What is the structure of secondary dentin?

A

Simiar to primary dentin- contain tubules
Tubular patterns are less regular
Odontoblasts become more crowded

48
Q

How does growth of secondary dentin differ to that of primary?

A

Secondary dentin grows much slower in increments

49
Q

What clinical impact does secondary dentin have?

A

It reduced the size of the pulp chamber and root canal diameter with age which can make endodontics more difficult

50
Q

When does tertiary dentine form?

A

In response to external stimulations such as cavities

51
Q

What are the two mechanisms by which tertiary dentine is formed?

A

Reactionary formation

Reparative formation

52
Q

What is reactionary formation of tertiary dentine?

A

Dentin is formed from pre-existing odontoblast

53
Q

What is reparative formation of tertiary dentine?

A

New odontoblasts are formed from pulpal progenitor cells due to death of previous odontoblasts

54
Q

How is translucent dentin formed?

A

Due to dentinal tubules being filled in response to external stimuli such as attrition or slow advancing caries

55
Q

In what way is the mineral composition of translucent dentine and peritubular dentine different?

A

Translucent is composed of crystalline and may contain salivary components due to caries

56
Q

What are dead tracts?

A

Empty tubules that are sealed at the pulpal end by tertiary dentin

57
Q

How are empty tubules formed?

A

Due to the death of odontoblasts or odontoblasts that have stopped their function

58
Q

Where are dead tracts more common

A

Secondary dentin

OCB02 (18 decks)

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