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Enamel, Dentine and Pulp > Dentine > Flashcards

Flashcards in Dentine Deck (27)
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1

dentine is not seen unless the enamel is worn away. what are the differences between dentine and enamel

dentine is yellow, enamel translucent
dentine = sensitive, enamel= not sensitive
dentine is formed throughout life, enamel isn't
dentine has a collagen protein matrix, enamel does not

2

what is dentine

a tissue made of small tubules arranged parallel within a collagen matrix

3

what is the diameter of the dentine tubules

3 um

4

what do the dentine tubules contain

odontoblasts- dentine forming cells
fluid

5

what is the composition of dentine

65% inorganic HAP
35% organic and water

6

how is HAP arranged in dentine

HAP is found on/in collagen fibrils of organic matrix

7

how are the collagen fibrils arranged in dentine

they run in PARALLEL to the pulpal surface

8

dentinal tubules run from the pulpal surface to the EDJ/CDJ. what course do they follow

a curved, sigmoid course = produces primary curvatures
and secondary curvatures
more branched at the EDJ, wider at the pulpal surface

9

what is the difference between the primary and secondary curvatures

the secondary curvatures are smaller, more frequent, wave-like tubules

10

what is peri-tubular dentine

over-time, the dentine that is deposited within the walls of the dentinal tubules= narrows lumen

11

what two things are distinct about the matrix of peri-tubular

does not have collagen fibres- rather an unidentified protein
it is hyper-mineralised

12

what are the incremental lines of dentine

1. Von Ebners- daily incremental line, diurnal rhythm, 4um spacing
2. Andresons line- superimposed on von ebner's, 20um apart, more prominent, long-period lines
3. Contour lines of Owen- congruence of secondary curvatures, seen due to optical effects
4. Schreger line- congruence of primary curvatures, seen due to optical effects

13

dentine may be classified by its region. what does this include

mantle dentine- region beneath enamel, first formed

circumpulpal dentine

primary dentine- dentine made during initial tooth development, fast forming

secondary dentine- dentine made over life, slow forming

peritubular dentine- dentine in the walls of dentinal tubules

inter-tubular dentine- dentine found in between the dentintal tubules

14

what are the different types of dentine

sclerotic dentine
dead tract
irregular secondary dentine (reactionary/ reparative)

15

how is sclerotic dentine formed

with matruation, the dentinal tubueles become filled with peritubular dentine
the intertubular dentine and dentinal tubules both have the same refractive index= region of translucency= sclerotic dentine

16

why does sclerotic dentine form

normal ageing process

defensive response to stimuli (severe attrition, slow forming caries)

17

why is irregular secondary dentine formed

when there is fast caries lesion progression, more dentine is laid down at the pulpal surface.

18

secondary dentine can be divided into...

reactionary- dentine made by the existing odontoblasts which did recover from the insult. the dentine is ordered

reparative- dentine made by odnotoblast-like cells because odontoblasts did not recover from insult. the dentine laid down is IRregular and BONE-LIKE

19

what are dead tracts

this defines the layer of dentinal tubules below a lesion that does not contain odontoblast processes, filled with air/debris= appear black

20

what is different about the mineralisation of dentine that makes it similar to bone

occurs on a mineralisation front
involves calco-spherates fusing one by one with the mineralisation front

21

what are calco-spherates

calcification spheres

22

what is inter-globular dentine

hypo-mineralised area
caused by calco-spherates fusing with one another BEFORE fusing with the mineralisation front hence do not get mineralised properly

23

which cells produce the dentine matrix

odontoblasts

24

what is the mineralisation front

where the HAP is deposited.

25

in which direction does the mineralisation front move across all the zones of dentine

mineralised dentine
un-mineralised pre-dentine
the odontoblast layer
the cell free zone- fewer cell bodies
body of the pulp

26

what is found in un-mineralised pre-dentine

calco-spherates
no mineral
lots of type 1 collagen fibres, and non-collagenous proteins

27

describe how mineralisation occurs in dentine

1. odontoblasts produce dentine matrix where dentine is deposited. the front travels in this direction
2. at the pre-dentine, the calco-spherates each fuse with the front to become subsumed within the bulk of mineralised dentine