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MCQ 1.1 > Enamel And Dentine > Flashcards

Enamel And Dentine Flashcards

1
Q

List 4 mineralised tissues

A

Alveolar bone
Cementum
Dentine
Enamel

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2
Q

List 4 non mineralised tissues

A

Oral mucosae
Dental pulp
Gingivae
Periodontal ligament

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3
Q

What forms the bulk of the tooth tissue

A

Dentine

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4
Q

What covers the crown of the dentine

A

Enamel

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5
Q

What covers the root of the dentine

A

Cementum

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6
Q

What is the appearance of dentine

A

Fine parallel tubules within a collagenous matrix for permeability
Rigid elastic tissue pale yellow

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7
Q

What is the unmineralised dentine pulp junction known as

A

Predentine

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8
Q

What creates dentine

A

Odontoblasts which then stimulate ameloblasts

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9
Q

Is dentine a vital tissue

A

Yes

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10
Q

What is the function of dentine

A

To act as a shock absorber dissipating large loads and force throughout the tooth structure highly elastic

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11
Q

How hard is dentine compared to other structures of the tooth

A

Harder than bone and cementum but softer than enamel

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12
Q

What is dentine composed of

A

70% inorganic mineral salts (hydroxyapatite crystals embedded in a collagen matrix)
20% organic substance (proteins)
10% water

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13
Q

List 6 non collagenous proteins in dentine

A

Dentine sialo phosphoproteins (DSPP)
Proteoglycans
Gla proteins
Acidic proteins
Growth factors
Lipids

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14
Q

What is the define between tubules called

A

Intertubular dentine

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15
Q

What shape does dentine follow

A

A curved sigmoid route known as primary curvatures (aka schreger lines)

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16
Q

What is the major feature of dentine

A

It’s dentinal tubules

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17
Q

What are lines of Owen

A

The small changes in direction in dentine known as secondary curvatures

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18
Q

When does secondary dentine appear

A

After completion of tooth formation increased crowding of odontoblasts

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19
Q

Where are dentinal tubules mostly formed

A

By the pulpal floor

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20
Q

Where do dentinal tubules mainly branch

A

At the periphery of the enamel dentine junction

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21
Q

What is translucent dentine

A

Forms with ageing due to tubule occlusion by deposits of peritubular dentine

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22
Q

Where is translucent dentine more pronounced

A

At the root apex

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23
Q

What are the 2 tertiary dentine synonyms

A

Reactionary dentine
Reparative dentine

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24
Q

What is tertiary dentine

A

Pulp induced to form calcified material in addition to 1st and 2nd dentine by a variety of external stimuli

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25
Q

What are the 5 external stimuli for tertiary dentine

A

Caries
Attrition
Cavity preparation
Microleakage around restorations
Trauma

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26
Q

What is reactionary dentine

A

Define formed in response to injury/insult made from existing odontoblasts

27
Q

What is reparative dentine

A

Dentine formed in response to stimulus made from progenitor cells/newly formed odontoblasts

28
Q

Where is peritubular dentine found

A

In wall of tubules highly calcified

29
Q

Where is intertubular dentine found

A

Between tubules highly calcified

30
Q

where is mantle dentine found

A

Outermost layer 1st dentine formed

31
Q

Where is circumpulpal dentine found

A

Around the pulp uniform in structure except at the edges is the bulk of the dentine

32
Q

What is primary dentine

A

Formed prior to apical completion formed more rapidly and more mineralised

33
Q

What is secondary dentine

A

Formed after completion of root formation formed more slowly and is less mineralised than primary

34
Q

Where is enamel thickest

A

At the cusps/incisal regions

35
Q

What is special about the primary dentition of enamel

A

It is more opaque crystalline form therefore appears whiter

36
Q

List 4 enamel functions

A

Mastication
Aesthetic
Protection
Dissipation of forces

37
Q

How hard is enamel in knoop

A

296

38
Q

How hard is dentine in knoop

A

64

39
Q

What is enamels composition

A

96-97% mineral salts (hydroxyapatites, fluorides, carbohydrates)
3-4% organic substance (fibrillar matrix)

40
Q

How is enamel structured

A

It is organised into rods (prisms) and interrods (interprismatic substance)

41
Q

Where do ameloblasts come from

A

The inner enamel epithelium

42
Q

What does amelogenesis do

A

Secrete matrix proteins that are responsible for creating and maintaining an extra cellular environment favourable to mineral deposition

43
Q

What are the 3 main stages of amelogenesis

A

Presecretory stage
Secretory stage
Maturation stage

44
Q

What does the first step of amelogenesis produce

A

A partially mineralised enamel 30%

45
Q

what does the second step of amelogenesis involve

A

An influx of additional mineral content with the removal of material and water resulting in the 96% mineralisation

46
Q

What are the 2 parts to maturation stage of enamel

A

Transitional phase
Maturation proper

47
Q

What is maturation proper

A

The ABs become involved in the removal of water and organic material

48
Q

What is the transitional phase

A

After the enamel has formed
ABs undergo significant morphological changes preparing for maturation
Reduction of AB height and a decrease in their volume and organelle content

49
Q

What are the ABs in enamel

A

Referred to as post secretory cells although they still secrete other essential proteins

50
Q

What is the maturative stage

A

Water and organic material is selectively removed from enamel with addition of inorganic material

51
Q

What do ruffle ended ameloblasts do

A

Release of inorganic material
Proximal junctions are leaky and distal junctions are tight

52
Q

What do smooth ended ameloblasts do

A

Remove proteins and water
Distal junctions are leaky while proximal junctions are tight

53
Q

What is amelogenin

A

Accumulates during the secretory stage

54
Q

What is enamalin

A

Crystal nucleation and growth

55
Q

What is ameloblastin

A

Undergoes rapid degradation
Promotes mineral formation and crystal elongation
Highest concentration at enamel growth sites
Secreted together with amelogenins

56
Q

What is the life of sulfated glycoproteins

A

Short half life in the enamel

57
Q

Where is the tuftelin and what does it do

A

Localises at the DEJ and participates in its establishment

58
Q

What pattern does enamel have

A

Striae of retzius

59
Q

How does the pattern of enamel form

A

Because of a weekly rhythm of enamel production resulting in structural alterations of the rods

60
Q

What type of striation does enamel have

A

Cross striations forming intervals across the rods

61
Q

What is bands of hunter and schreger

A

Optical phenomenon produced by the changing orientations of adjacent groups of rods

62
Q

What is gnarled enamel

A

Enamel tufts and lamellae
Perikymata aka imbrication lines

63
Q

What contains the greatest concentration of enamel than the rest of the enamel

A

Gnarled enamel
Is projected from the DEJ for a short distance into the enamel

64
Q

How is enamel formed

A

Secreted by ameloblasts via amelogenesis

MCQ 1.1 (43 decks)

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