Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

1 - IOE - Dental Anatomy > Dentine > Flashcards

Dentine Flashcards

1
Q

Why is the dentine that covers the bulk of the crown not visible

A

It is covered by the enamel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What does the deep surface of dentine form?

A

Forms the walls of the pulp chamber

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Which tissue has a thicker crown: dentine or enamel

A

Dentine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What’s the advantage of dentine being thick

A
  • Helps protect the pulp tissue at the core of the tooth
  • Provides room for replacement
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

When can dentine be exposed

A

When cementum and enamel fail to meet at the CEJ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What can expose dentine

A
  • Gingival recession
  • Significant tooth surface loss
  • Caries
  • Crown fracture
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What can exposed coronal and root dentine cause

A

Can cause clinical symptoms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What colour is dentine

A

Dentine is pale yellow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is dentine

A

Mineralised connective tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are dentinal tubules

A

Channels running from the pulp to the outer dentine at the ADJ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How hard is dentine in relation to other mineralised coinnective tissue

A

Dentine is harder than bone and cementum but softer than enamel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Where does dentine obtain its rigidity from and why is this useful

A
  • Mineral content
  • Support enamel
  • Maintain the shape of the tooth
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Explain the relationship between dentine and mastication

A

Exposed dentine cannot withstand abrasive forces of mastication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What provides dentine with greater compressive, tensile and flexural strength than enamel
Why is this important

A
  • The organic matrix and tubular architecture
  • This provides dentine flexible support needed by the overlying brittle enamel
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What does dentine’s permability depend on

A
  • Size and patency of tubules
  • Age change
  • Pathalogical processes affecting the tooth
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why is the mineral in dentine more soluable in acid than in enamel

A

Dentine contains hydroxyapatite crystallites, however there are more impurities than in enamel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the structural difference between hydroxyapatite crystallites in dentine and enamel

A

In dentine:
- Much smaller in cross section
- Shorter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How are the hydroxyapatite crystals arranged

A
  • Along and in-between collagen fibrils
  • Fibrils form a meshwork
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the principal collagen fibril

A

Type 1 collagen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How do most collagen fibrils run in relation to the ADJ

A

Parallel to the ADJ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Why is the mineral content in dentine lower than in enamel

A
  • Dentine tubules and collagen meshwork take up a significant proportion of the tissue volume
  • Hydroxyapatite crystals aren’t as tightly packed together as in enamel
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What do non-collagenous proteins include

A
  • Phosphoproteins
  • Proteoglycans
  • Glycoproteins
  • Growth factors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the main non-colagenous proteins

A
  • Dentine phosphoprotein (DPP)
  • Dentine matrix proteins 1 (DMP-1)
  • They have different actions during mineralisation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What role do proteoglycans have in collagen fibril assembly

A
  • Cell adhesion
  • Migration
  • Proliferation
  • Differentiation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Where are lipids detected?

A

Detected at the mineralising front and are thought to play a role in mineralisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What are lipids in the form of

A
  • Phospholipids
  • Cholesterol
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Where are phospholipids found

A

The spaces between collagen fibrils along with the proteoglycans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

How quickly is the peritubular dentine laid down

A

Slowly throughout life

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Why does dentine become transluscent

A
  • As groups of tubules become totally filled, reigons become transluscent
  • Tubules and the intertubular dentine have approx the same refractive index
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What happens when a ground section of a root is placed in water

A

Reigons blocked by peritubular dentine will appear translucent, while reigons with patent tubules will fill with water and appear opaque

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Where do dentinal tubules first come occluded
What happens during physiological ageing

A
  • Tubules first become occluded at the root apex
  • Transluscent areas gradually extend cervically and towards the root canal with physiological ageing
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Describe how secondary dentine can be used to determine the age of a person from their teeth

A

The extent of transluscent dentine is related to chronological ageing so the feature is used in forensic age

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What does sclerotic dentine produce and how does it differ from transluscent dentine?

A
  • Produces transparent reigons
  • Differs from transluscent dentine as it isn’t related to chronological age
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What type of dentine is sensitive

A

Exposed dentine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What are the proposed mechanisms of dentine sensitivity

A
  1. Direct innervation
  2. Odontoblasts act as sensory endings
  3. Hydrodynamics (fluid flow)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Which nerves may suggest simple direct simulation of the nerves

A

Nerves within dentinal tubules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What are the 3 theories of dentine sensitivity

A
  • Direct stimulation on nerves theory
  • Odontoblasts acting as receptors theory
  • Hydrodynamic theory
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Explain the ‘direct stimulation on nerves’ theory

A
  • Stimulus trigers direct response in nerve
  • Impulse passing down to the nerve and onto central nervous system via Raschkow’s plexus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Explain the ‘odontoblasts acting as receptors’ theory

A
  • Response is triggered in the odontoblast process
  • There’s synapses between odontoblast cell bodies and adjacent nerves
  • Impulse travels down to cell body where it triggers a synapse + onto nerve plexus
40
Q

Explain the hydrodynamic theory

A
  • Stimulus applied to dentine triggers a flow of fluid within tubules
  • Movement is sufficient to depolarise nerve endings
41
Q

Why is it generally accepted that hydrodynamics is the most likely mechanism

A
  • It would act regardless of precise position or number of nerve endings
  • As tubules are narrower, the further away from the pulp one goes, any given volume of fluid would flow at a faster rate, hence a greater stimulus and greater sensitivity in that reigon
  • Dentine sensitivity can be reduced or removed by occluding the tubules as evidenced by anti-sensitivity toothpastes
42
Q

What are the arguments against the ‘stimulation on nerves’ theory

A
  • Nerve axons appear to be absent in the outer parts of dentine - most sensitive reigon in dentine
  • Application of local anaesthetics to the surface of dentine doesn’t remove the sensitivity
43
Q

What are the arguments against ‘odontoblasts acting as receptors’ theory

A
  • Odontoblast processes may not extend to the ADJ
  • Odontoblasts have not been shown to have synaptic junctions with nerve fibres
44
Q

How does dentine maintain is vitality

A
  • Through odontoblasts
  • The cell bodies which lie at the periphary of the dental pulp
  • Their processes extending into the dentinal tubules
45
Q

What do the odontoblast cells do

A
  • Lay down + mineralise dentine matrix
  • Help maintain its integrity when dentine structure is damaged through disease or trauma
46
Q

Where is the extracellular dentinal fluid that passes along the dentinal tubules derived from
Why may this be important

A
  • The vasculature of the dental pulp
  • May be important in maintaining the health of the cellular and hard tissue environment in dentine
47
Q

How does odontoblasts acting as a selective barrier help

A
  • Allow tissue fluid to enter dentinal tubules
  • May slow the inward movement of toxins during the progression of dental caries
48
Q

What is the relationship between odontoblasts and the formation of tertiary dentine

A

The responsiveness of dentine to external stimuli resulting in the formation of tertiary dentine is mediated by odontoblasts

49
Q

What are odontoblasts capable of producing

A

Pro-inflammatory mediators in response to bacterial toxins such as lipopolysaccharides

50
Q

Where do dentinal tubules commonly fill in as a response to an external stimulus

A
  • Under slowly advancing caries
  • Beneath areas of severe attrition
51
Q

How can occlusion of groups of dentinal tubules by deposition of sclerotic dentine offer protection

A

By slowing down progression of lesion towards the pulp

52
Q

What is the mineral in sclerotic dentine

A

The mineral is crystalline and possibly an apatite, although plate-like crystals of octocalcium phosphate have also been reported

53
Q

Whats the difference in mineral concentration in sclerotic dentine and young dentine

A

Sclerotic dentine has a significantly higher mineral concentration

54
Q

Whats the difference between sclerotic dentine and normal dentine

A

Sclerotic dentine exhibits almost no yielding before failure

55
Q

What happens when primary odontoblasts are killed by an external stimulus

A
  • Empty dentinal tubules are left
  • Tubules may be sealed at their pulpal end by tertiary dentine
56
Q

What happens when the mounting medium dont enter the sealsed-off tubules when ground sections are prepared and mounted?

A

The tubules remain air-filled, so they will appear dark under a microscope and are histologically termed dead tracts

57
Q

What is tertiary dentine used to describe

A

All hard tissue deposited on the pulpal surface in response to an external stimulus:
Stimuli may include caries, tooth surface loss and damage to dentine

58
Q

What is tertiary dentine: a response tissue or an age change

A
  • Response tissue
  • Deposited at specific sites, providing a barrier to the progress of caries and toxins
59
Q

Where can tertiary dentine be found in older teeth

A

On the pulpal aspect of secondary dentine

60
Q

Where is tertiary dentine restricted to

A

The reigon behind the irriatation

61
Q

What does the appearance and composition of tertiary dentine depend on

A

The types and severity of the stimulus applied to dentine

62
Q

How might tertiary dentine resemble secondary dentine

A

Having a regular tubular structure

63
Q

How might tertiary dentine resemble bone

A

May have a few/irregularly arranged tubules or be atubular

64
Q

What does the term ‘reactionary dentine’ refer to

A

The dentine forming in response to an insult in which existing odontoblasts recover and continue to form dentine, although dentine will have an irregular apperance with fewer tubules

65
Q

What does the term ‘reparative dentine’ relate to

A

Dentine forming after a stimulus in which the original odontoblasts in the associated reigon have been destroyed and new calcified tissue has been formed by newly differentiated ‘odontoblast-like’ cells

66
Q

How do you form reparative dentine

A

Odontoblast-like cells differentiate from a stem cell population

67
Q

Whats allows for the divison of dentine into different reigons

A

The properties and composition of mineralised dentine between the predentine adjacent to the pulp and the ADJ

68
Q

What is the bulk of dentine in the crown and root called

A

Circumpulpal dentine

69
Q

What is circumpulpal dentine’s structure like?

A

Uniform, except at its periphery where interglobular dentine may be found. Where interglobular dentine is absent, mantle dentine forms its peripheral boundary

70
Q

Where is the granular layer of Tomes found

A

At the peripheral reigon in root dentine

71
Q

What are the 2 explanations for the existance of the granular layer

A
  1. Dentinal tubules in the area branch more profousely and loop back on themselves creating air spaces in ground sections, resulting in internal reflection of transmitted light
  2. Due to the incomplete fusion of calcospherites (much smaller than those found in the crown
72
Q

Describe the hyaline layer

A

Sits outside of the granular layer & appears as a narrow structureless band - may have a role in bonding cementume to dentine

73
Q

What is predentine

A

Unmineralised intermost layer in the crown and root - represents the initially laid down dentine matrix before its mineralisation

74
Q

What colour is predentine in demineralised sections stained with haematoxylin and eosin
Why is it this colour

A

Distinct pale-staining apperance due to a difference in the composition of its matrix

75
Q

Where is secondary dentine found

A
  • In older teeth
  • Inner, pulpal part of the circumpulpal dentine
76
Q

How different is the structure of primary and secondary dentine

A

They have a very similar structure

77
Q

What is secondary dentine laid down by

A

Original odontoblasts as an age-related change in the rate of dentine formation

78
Q

As dentine deposition continues, what happens to pulp volume

A

Decreases

79
Q

What percentage of odontoblasts die over a 4-year period

A

50%

80
Q

What does the death of odontoblasts likely lead to in relation to the contour line

A

There is a change in the direction of the tubules

81
Q

What does a slower rate of deposition of dentine do to the tubular pattern

A

Makes the pattern a little less regular than that of primary dentine

82
Q

What may the continuing deposition of secondary dentine throughout life contribute to

A

May contribute to the barrier function of the tissue

83
Q

What is mantle dentine

A
  • First-formed layer of dentine
  • Most peripheral layer of dentine
  • Found beneath the enamel
84
Q

What is the width of mantle enamel

A

Varies from 20-150 microns

85
Q

How does mantle dentine differ from the bulk of curcumpulpal dentine

A
  • Mantle dentine is lightly less mineralised
  • Mantle dentine displays branching of dentinal tubules
  • Mantle dentine has collagen fibrils orientated perpendicular to the ADJ
86
Q

What do the speical properties of mantle dentine help to prevent

A

Small cracks developing in the enamel near the ADJ from speading into the dentine

87
Q

Where is interglobular dentine found

A

Beneath the mantle layer in the crown and beneath the granular layer in root areas where dentine mineralisation is incomplete

88
Q

How do uncalcified, interglobular areas appear when ground sections are viewed in transmitted light

A

They appear dark due to the internal reflection of light

89
Q

What are Schrenger lines

A

Lines associated with the primary curvatures of the dentinal tubules - where peaks of the sigmoid primary curvatures concide, they form broad bands known as Schrenger lines

90
Q

What are Contour lines of Owen

A

Lines associated with the secondary curvatures of the dentinal tubules - They give rise to an optical effect resulting in the apperance of lines known as the Contour lines of Owen

91
Q

Why are lines seen at the junction of primary and secondary dentine

A

There is a coincident change in tubule direction

92
Q

What are the daily incremental lines

A

Where dentine is laid down at about 4µm per day in a diurnal rhythm

93
Q

Describe von Ebner’s lines

A

Short-period markings may be seen as alternating dark and light bands, each pair reflecting the diurnal rhythm of dentine formation

94
Q

What are Andresen lines

A

Lines which are superimposed on von Ebner’s lines and are more prominent

95
Q

What is between each long-period line

A

6-10 paids of short period lines with an average 1 week periodicity similar to the long-period striae of Retzius in enamel

1 - IOE - Dental Anatomy (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions