WEEK 6 - DENTINE + PULP Flashcards

1
Q

what is dentine?

A

the mineralised tissue that forms the bulk of the tooth

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2
Q

What happens to dentine throughout life?

A

it increases in thickness at the expense of the pulp

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3
Q

what commences dentinogenesis

A

the formation of predentine by odontoblasts

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4
Q

what does dentine consist of?

A

a large number of small parallel tubules in a collagen matrix

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5
Q

what colour is dentine?

A

pale yellow

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6
Q

Is dentine permeable?

A

yes

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7
Q

What is the chemical composition of dentin?

A

70% inorganic, 20% organic, 10% water

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8
Q

What is the inorganic component?

A

calcium crystals that give it its hardness

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9
Q

what is the organic component of dentin?

A

collagen and ground substance

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10
Q

What is the life cycle of odontoblasts?

A

preodontoblasts, secretory odontoblasts, resting odontoblasts

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11
Q

What are the features of preodontoblasts?

A

small ovoid cells, high nucleus to cytoplasmic ratio

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12
Q

What are the features of secretory odontoblasts?

A

large plump cell, open face nucleus

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13
Q

What are the features of resting odontoblasts?

A

thin, quiescent state

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14
Q

What are the 2 steps of dentinogenesis?

A

matrix formation and maturation

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15
Q

what is matrix formation?

A

after the differentiation of odontoblasts, it secretes predentin

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16
Q

what is the initial organic matrix (predentin) composed of?

A

small collagen fibrils and characteristic ground substance

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17
Q

What is the maturation or mineralization of dentin?

A

the formation of calcium hydroxyapatite crystals in the form of globules in the predentin

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18
Q

What are the two patterns of dentin mineralization that can be observed?

A

globular and linear calcification

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19
Q

where is primary dentin located and what are its histological features?

A

it is formed before completion of apical foramen and more rapidly and mineralized than secondary dentin

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20
Q

what is secondary dentin?

A

formed after completion of apical foramen, more slowly and less mineralized than primary. change of curvature

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21
Q

what is tertiary dentin?

A

formed in response to trauma, an irregular course of tubules

22
Q

what are dentinal tubules?

A

odontoblast processes that run in canaliculi following an S shaped path

23
Q

what forms the main bulk of dentine?

A

intertubular dentin

24
Q

what is peri-tubular dentin?

A

highly calcified matrix

25
Q

what is interglobular dentin?

A

unmineralized dentin

26
Q

what is tomes granular layer?

A

seen just below the surface of dentin where the root is covered my cementum, a spotty microscopic line

27
Q

what are the incremental lines of dentin?

A

Lines of Von Ebner, counter lines of owen, and neonatal line

28
Q

what is incremental lines of von ebner?

A

long period lines associated with the five day deposition cycle.

29
Q

long period lines associated with the five day deposition cycle.

A

parallel imbrication lines

30
Q

What is the neonatal line?

A

a disturbance in mineralization from the trauma of birth

31
Q

what is serotic dentin?

A

injury or aging tooth

32
Q

What are dead tracts in dentin?

A

empty tubules from the death of primary odontoblasts

33
Q

what is the innervation of dentin?

A

in the pulp, 25% are myelinated afferents

34
Q

describe dentin hypersensitivity

A

odontoblasts act as receptors and fluid moves through tubules stimulating the receptors in the pulp

35
Q

what are the 3 theories associated with dentin hypersensitivity?

A

direct nerve stimulation, odontoblast process associated with sensation, an hydrodynamic theory

36
Q

what is pulp?

A

the soft connective tissue responsible for nourishing the dentine

37
Q

where is pulp contained?

A

pulp chamber

38
Q

what are the two main divisions of pulp?

A

coronal pulp and radicular pulp

39
Q

what is the largest and second largest group of cells in the pulp?

A

fibroblasts and odontoblasts

40
Q

what are the 4 zones of pulp?

A

odontoblastic layer, cell-free zone of Weil, cell-rich zone, pulpal core

41
Q

where is the odontoblastic zone of pulp located?

A

pulp perifery

42
Q

where is the cell free zone of weil located?

A

beneath odontoblasts, in coronal pulp

43
Q

where is the cell rich zone?

A

adjacent to cell free zone, in coronal pulp

44
Q

what is the pulp core?

A

the major vessels and nerves of the pulp

45
Q

what are the cells of the pulp?

A

odontoblast, fibroblast, macrophage, dendritic cell, lymphocyte, mast cell

46
Q

what does the extracellular component of the pulp consist of?

A

collagen fibres and ground substance

47
Q

what happens to collagen content in the pulp as you age?

A

increases

48
Q

what happens to pulp as you age?

A

gets smaller, less vascular, forms pulp stones

49
Q

what are pulp stones?

A

calcified masses of dentin

50
Q

what is dystrophic calcification?

A

originate in relation to blood vessels