Brainscape's Knowledge GenomeTM

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


See full index

Craniofacial and Tooth Biology > 14. Dentinogenesis > Flashcards

14. Dentinogenesis Flashcards

1
Q

Chemical properties of dentine

A
  • 70% inorg - calcium hydroxyapatite crystals
  • 20% org - mainly collagen fibrils
  • 10% water
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Dentine is more or less mineralised than enamel

A

less

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

What inorganic matter is in dentine?

A
  • calcium hydroxyapatite crystals (Ca10(PO4)6(OH)2)
  • HA crystals appear as uniform small plates between type 1 collagen fibrils
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

HA crystals form what shape in dentine?
Are these smaller or larger than the ones in enamel?

A

uniform small plates
smaller

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

List components of organic matrix in dentine

A
  • collagen fibrils
  • proteoglycans
  • glycoproteins
  • phosphoproteins
  • growth factors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What types of collagen are present in dentine?

A
  • mainly 1 - 90%
  • 10% 3
  • traces of 5 and 6
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Proteoglycans in dentine are similar to those in…

A

bone

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

3 types of glycoprotein in dentine

A
  • osteonectin
  • osteopontin
  • dentine sialoproteins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Where else are dentine phosphoproteins found?

A
  • nowhere
  • unique to dentine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

2 types of growth factors in dentine

A
  • transforming growth factors
  • bone morphogenic proteins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Properties of dentine

A
  • softer than enamel
  • high tensile strength than enamel
  • more resilient/elastic to support brittle enamel
  • porous
  • sensitive due to pulp innervation
  • reactive to damage - repair ability/tertiary dentine
  • pulp-dentine complex is living - changes with age
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Clinical relevance of dentine properties

A
  • dentine is less radiopaque than enamel to contrast radiolucent pulp
  • dentine is resilient/slightly elastic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Dentine formation begins at which point of tooth development?

A
  • late bell stage at cusp tip
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Dentine is formed by what cells?

A

odontoblasts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does dentine form?

A
  • mesenchymal cells
  • differentiate from dental papilla (future dental pulp)
  • differentiate when receiving molecular signals from pre-ameloblasts (derived from inner enamel epithelium IEE cells)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Odontoblasts secrete what?

A

predentine

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

Explain predentine secreted by odontoblasts

A
  • collagen fibres (type 3) forming von Korff’s fibres at 90 degrees angle to enamel-dentine junction
  • begin to secrete smaller type 1 collagen fibrils parallel to EDJ
  • secrete matrix vesicles (mv)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Define ‘predentine’

A

unmineralised area between odontoblast layer and mineralising front

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How is mineralising front formed?

A
  • odontoblasts develop cell processes
  • initiation of mineralisation with matrix vesicle
  • cystallites burst out of vesicle and form the mineralising front
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Define ‘matrix vesicles’

A
  • small membrane-covered vesicles produced by odontoblasts and secreted into dentine matrix that surrounds the odontoblasts
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Size range of matrix vesicles

A

25-250 nm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Matrix vesicles contain …

A
  • phospholipids that bind to calcium
  • alkaline phosphatase, an enzyme that increases phosphate conc by destroying inhibitor of mineralisation (pyrophosphatase)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Matrix vesicles have been observed during what? What does this mean?

A
  • mineralisation of mantle dentine
  • may or may not be involved with mineralisation of circumpulpal dentine ( only seen at mantle)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

There is lots/no mineralisation in or near collagen fibres
What does this mean?

A
  • no
  • collagen is not responsible for initiating mineralisation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Dentine is first deposited as … and it’s gradually mineralised at …

A
  • predentine
  • mineralisation front
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Explain predentine thickness

A
  • thickness remains constant as amount that calcifies is balanced by addition of new unmineralised matrix
  • during ageing, predentine diminishes in thickness
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

2 types of dentine mineralisation patterns

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

What determines whether dentine mineralisation is linear or globular?

A

speed of dentine formation

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

Where is globular calcification normally found?

A
  • mantle dentine
  • where mineralisation occurred in matrix vesicles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

In circumpulpal dentine, what kind of dentine mineralisation happens?

A
  • linear or globular
  • depends on rate of dentine deposition
  • when fast, globular calcification occurs
  • slow, mineralisation is gradual and mineralising front looks straight/linear
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What happens in globular calcification?

A
  • calcospherites (globular masses of mineralised dentine) form within collagen matrix
  • they increase in size using fuse to form a single calcified mass
  • if calcification proceeds fast, incomplete fusion of calcospherites can lead to formation of hypomineralised interglobular dentine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Where is interglobular dentine found?

A

upper third of circumpulpal dentine

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

Define ‘interglobular dentine’

A
  • leaf-like, hypomineralised areas
  • between spheres or globules of mineral
34
Q

2 adaptations of EDJ to role

A
  • crater-like depressions to increase surface area of EDJ
  • sharp edges to help attachment of enamel to dentine
35
Q

Enamel spindles are formed from an … that has intercalated between two … and extends into the …

A
  • odontoblast process
  • ameloblasts
  • enamel
36
Q

What is seen in mantle dentine?

A

branched tubules

37
Q

Mantle dentine is the … layer of …

A

outermost
crown dentine

38
Q

Hyaline layer is the outermost layer of …

A

root dentine

39
Q

Why are there S-shaped tubules in the coronal region of the crown?

A
  • due to crowding of odontoblasts
  • they are pushed apically as dentine grows inwards towards pulp
40
Q

Why are there linear shaped tubules in cervical region of crown?

A
  • beneath cusps/incisal edges/root dentine
  • little or no crowding of odontoblasts
41
Q

There are … shaped tubules in coronal region of crown but … shaped in cervical region

A

S
linear

42
Q

Define ‘secondary curvature in dentinal tubules’

A
  • slightly changes in tubule direction in dentine deposition
  • creates wavy dentinal tubules
43
Q

2 types of incremental growth lines

A
  • von Ebner lines
  • Andresen lines
44
Q

Explain von Ebner lines

A
  • dentine deposited daily, forming daily lines
  • lines 3-4 micrometres apart (less than 2 near root surface)
  • equivalent to cross striations in enamel
  • less defined with closer spacing
45
Q

Explain Andreson lines

A
  • long period growth lines
  • lines 20 micrometres apart (around 6-10 von Ebner lines)
  • equivalent to striae of Retzius in enamel
  • more sharply defined with wider spacing
46
Q

What happens when secondary curvature is pronounced and coincides in adjacent tubules?

A
  • contour line of Owen forms
  • caused by metabolic stress/disturbances during dentine formation
  • these lines are accentuated growth lines (Von Ebner) and hypomineralised
47
Q

What is the most prominent incremental growth line?

A
  • neonatal line
  • due to disturbances of dentine formation by birth process
48
Q

How is an Owen line produced and what does it represent?

A
  • bending of dentinal tubules
  • reflects a disturbance in dentine formation (like the accentuated lines in enamel)
49
Q

2 ways to classify dentine

A
  • by time of development
  • anatomical location/histology
50
Q

4 divisions of dentine under ‘time of development’ class

A
  • predentine
  • primary dentine
  • secondary dentine
  • tertiary dentine
51
Q

Predentine is an … dentine …

A
  • unmineralised
  • matrix
52
Q

Primary dentine forms when?

A

during tooth development

53
Q

Secondary dentine forms when?

A

after root completion

54
Q

Tertiary dentine forms when?

A

in response to stimulus to repair

55
Q

2 divisions of dentine within anatomical location/histology

A
  • coronal dentine
  • root dentine
56
Q

Types of coronal dentine

A
  • mantle dentine (outermost layer of crown dentine)
  • circumpulpal dentine (forms bulk of crown) split into interglobular, intetubular and intratubular dentine, sclerotic dentine
57
Q

Which forms first? Mantle/cicumpulpal dentine?

A

mantle

58
Q

When does ‘interglobular dentine’ form?

A

when dentine is mineralised rapidly

59
Q

Where does intertubular dentine form?

A

between dentinal tubules

60
Q

Alternative name for intratubular dentine

A

peritubular dentine

61
Q

Where does intratubular dentine form?

A

inside dentinal tubules

62
Q

When does sclerotic dentine form?

A
  • caused by complete obliteration of dentinal tubules
63
Q

Explain root dentine

A
  • hyaline layer is outermost of root dentine
  • granular layer of Tomes below hyaline layer
  • intertubular, intratubular and sclerotic dentine
64
Q

Primary dentine is all dentine formed until …

A

completion of the root formation

65
Q

Secondary dentine forms after …
Over time, it reduces …

A
  • completion of root formation
  • size of pulp chamber and root canals
66
Q

Tertiary dentine is produced in response to …

A

external stimuli
- attrition, caries, cavity prep etc
- for tooth repair and protection2

67
Q

2 types of tertiary dentine

A
  • reactionary
  • reparative
68
Q

Define ‘reactionary dentine’

A
  • when original odontoblasts continue to function in dentine deposition
  • contains less dentinal tubules
  • formed after weak stimuli/injury for a slow response
69
Q

Define ‘reparative dentine’

A
  • when original odontoblasts die, newly recruited odontoblast-like cells begin depositing dentine
  • these are induced from pulp stem cells
  • less structured in response to severe injury/stimuli for a fast response
70
Q

In secondary dentine, there is a visible change in what?

A
  • direction of dentinal tubules
71
Q

Secondary dentine is the normal continuation of…

A

dentine formation occurring throughout life
- by odontoblasts lining pulp and root canals

72
Q

Secondary dentine forms a regular/irregular distribution?

A
  • irregular
  • mostly on roof and floor of pulp chamber
73
Q

Explain intratubular dentine

A
  • forms within dental tubule and lines inner surface
  • hypermineralised (40% more than surrounding dentine)
74
Q

Explain intertubular dentine

A
  • between dental tubules
  • in any primary or secondary dentine
  • less mineralised than intratubular dentine
75
Q

Tubule space appears …, ringed with …

A
  • black
  • white highly-mineralised intratubular dentine with grey intertubular dentine between
76
Q

Demineralisation of tooth completely removes …
What does this mean?

A
  • intratubular dentine
  • leaves an intratubular space making tubule appear wider separated only by intertubular dentine
77
Q

Define ‘sclerotic dentine’

A
  • continued formation of intratubular dentine leading to obliteration of tubules
  • once completed, termed sclerotic
78
Q

Sclerotic dentine appears … in ground sections
Why?

A
  • transparent
  • increased mineralisation
79
Q

Sclerotic increases with … Why?

A
  • age
  • in areas of attrition and caries of enamel
  • protects pulp against invading microorganisms
79
Q

Define ‘dead tracts’

A
  • when dentinal tubules have lost their odontoblast processes following death of odontoblasts or retraction of processes
  • tubules become empty and air filled
  • appears as dark bands in ground sections termed dead tracts
80
Q

2 explanations for Tomes granular layer

A
  • extensive branching and backward looping of odontoblast processes
  • incomplete fusion of calcospherites (like interglobular dentine)

Craniofacial and Tooth Biology (25 decks)

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