histoloy of dentine and pulp e lec

Question 1

how can dentine be studied

Answer 1

in both ground sections and demineralised sections

Question 2

what are ground sections

Answer 2

where the mineral is retained and the section is unstained

Question 3

what are demineralised sections

Answer 3

where the mineral is removed and the section is stained

Question 4

how can pulp be studied

Answer 4

only in demineralised sections

Question 5

what is a characteristic feature of dentine

Answer 5

the dentinal tubules which run from the pulp to the outer dentinal surfaces

Question 6

what do the tubules contain

Answer 6

contain fluid and odontoblasts

Question 7

what shape do the dentinal tubules follow

Answer 7

they follow an S shape called the primary curvature

Question 8

what is on top of the primary curvature

Answer 8

the secondary curvature is superimposed on the top of the primary curvature

Question 9

what does the secondary curvature look like

Answer 9

more frequent and small wave like deviations

Question 10

what might happen to the tubules

Answer 10

the tubules might be branched

Question 11

where is branching more evident

Answer 11

it is evident at the ADJ especially under the enamel in the tooth crown

Question 12

why does interglobular dentine form

Answer 12

arises due to incomplete fusion of calcospherites

Question 13

what is the mineral front as

Answer 13

dentine is laid down and mineralised

Question 14

what does the fusion trap do

Answer 14

it traps areas of poorly mineralised dentine in the form of arches which reflect the spherical nature of the calcospherites

Question 15

where can calcospherites be seen visibly

Answer 15

at the mineralisation front of forming dentine

Question 16

what can dentine be divided into

Answer 16

primary or secondary dentine

Question 17

what dentine is found in circumpulpal dentine

Answer 17

primary dentine

secondary dentine

Question 18

which is the first dentine laid down adjacent to the ADJ

Answer 18

mantle dentine

Question 19

how are the collagen fibres arranged in the mantle dentine

Answer 19

they are located perpendicular to the ADJ

Question 20

where do the collagen fibres in the mantle dentine arise from

Answer 20

some people think it arises from sub odontoblastic mesenchyme origin and not odontoblasts

Question 21

where is the evidence that the collagen fibres come from sub odontoblastic mesenchyme

Answer 21

from von korff fibres which are evident when to developing tooth is stained with silver

Question 22

how do we see the von korff fibres

Answer 22

when the developing tooth is stained with silver

Question 23

what lays down the basic shape of the dentine

Answer 23

primary dentine

Question 24

what is primary dentine

Answer 24

it lays down the basic shape of the dentine

Question 25

what happens once the tooth erupts

Answer 25

a slower rate of dentine production at the pulpal surface happens and the root is completed

Question 26

what is the dentine called that is produced slowly after the tooth erupts

Answer 26

regular secondary dentine

Question 27

what is the junction between the two types of dentine shown by

Answer 27

by a change in the direction of dentinal tubules

Question 28

how do dentinal tubules pass through from the ADJ to the pulpal surface

Answer 28

by following a shape called the primary curvature

Question 29

what might happen in the ground section

Answer 29

some tubules might be black

Question 30

why might tubules be black

Answer 30

due to the fact that they are no longer filled with fluid and fill with debris

Question 31

what might the tubules look like in a carious area

Answer 31

the tubules might look black due to odontoblasts being affected and form dead tracts

Question 32

the pulp dentine interface is composed of from exterior to interior

Answer 32

mineralised dentine pre-dentine (unmineralised except for the presence of calcospherites) odontoblasts cell free zone (of Weil) cell rich zone body of the pulp (a loose, vascular and well innervated connective tissue)

Question 33

what is predentine

Answer 33

it is the collagenous matrix before mineralisation

Question 34

what lies between the mineralised layer and odontoblast layer

Answer 34

a layer of predentine

Question 35

what is the cell responsible for forming dentine

Answer 35

odontoblasts

Question 36

how is dentine formed

Answer 36

initially predentine is formed | which is then mineralised by calcospherites

Question 37

what projects into the dentinal tubule

Answer 37

a process from the distal end of the cell

Question 38

what happens to pulp size as dentine mineralises

Answer 38

becomes smaller

Question 39

why does the pulp reduce is size

Answer 39

due to the dentine pseudostratified

Question 40

what happens to the cell count as dentine production continues

Answer 40

the cell count decreases as dentine goes from primary dentine to regular secondary dentine

Question 41

what does the odontoblast layer contain

Answer 41

capillary loops | unmyelinated nerve fibres

Question 42

where do capillary loops and unmyelinated nerve fibres orginate from

Answer 42

sub odontoblastic plexus

Question 43

what are calcospherites

Answer 43

small isolated globular structures which fuse with predentine to form mineralised dentine at the mineralisation front

Question 44

where does the cell free zone lie

Answer 44

below the odontoblast layer

Question 45

what is the H&E stain

Answer 45

hematoxin and eosin stain

Question 46

is the cell free zone real

Answer 46

many people think its artefactual due to shrinkage of the pulp layer away from the odontoblast layer

Question 47

what does the cell rich zone have

Answer 47

a high amount of cell nuclei

Question 48

what does the body of the pulp contain

Answer 48

the loose connective tissues

Question 49

what is the predominant cell type

Answer 49

fibroblasts

Question 50

what other cells nmight be present

Answer 50

macrophages

Question 51

what is also located in sub odontoblastic layers

Answer 51

undifferentiated mesenchyme

Question 52

the pulp also has

Answer 52

nerves and capillary loops which also supply the odontoblast layer

Question 53

where do nerves and capillaries enter the pulp from

Answer 53

the apical foramen

Question 54

where do the nerves have endings

Answer 54

between odontoblasts and within the dentinal tubules

Question 55

what might happen to the capillaries

Answer 55

they may become fenestrated

Question 56

why does the lesion in the dentine spread wider than the enamel

Answer 56

due to the way the enamel prisms around the fissure and lie adjacent to the ADJ

Question 57

why does sclerotic dentine arise

Answer 57

due to the dentinal tubules being completely occluded by peritubular dentine by odontoblasts

Question 58

why does peritubular dentine get deposited

Answer 58

as a againg process or as a reactionary process( defensive process) in a response to the overlying carious lesion

Question 59

when does the defensive process occur

Answer 59

if the lesion develops slowly which allows the dentinal tubules to fill slowly with peritubular dentine

Question 60

what is a dead tract

Answer 60

if the dentinal tubules cannot allow for this form of defence they retract and the tubule is empty and leads to the formation of a dead tract

Question 61

why does a dead tract occur

Answer 61

if the odontoblast cannot mount a defence it will withdraw the processes and form a dead tract. the dead tract can fill with debris and air during the grinding process and appears black

Question 62

what will happen if the odontoblast cell is still alive

Answer 62

it will try to seal the pupal end of the dentinal tubule with reparative dentine

Question 63

what happens if the odontoblast cells are dead

Answer 63

cells like sub odontoblastic cells produce a bone like material

Question 64

when is reparative dentine put down

Answer 64

reparative dentine is put down when the odontoblasts make an attempt

Question 65

what else is reparative dentine called

Answer 65

irregular secondary dentine

Question 66

what is reactionary dentine

Answer 66

it is when extant odontoblast cells lie down reparative dentine

Question 67

what should reparative dentine be reserved for

Answer 67

when the odontoblast cells have died and subodontoblastic cells replace them and lie down reparative dentine

Question 68

what does reparative dentine not have

Answer 68

it does not have dentinal tubules