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Enamel, Dentine and Pulp > Dentine > Flashcards

Flashcards in Dentine Deck (27)
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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


what is dentine

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


what is the diameter of the dentine tubules

3 um


what do the dentine tubules contain

odontoblasts- dentine forming cells


what is the composition of dentine

65% inorganic HAP
35% organic and water


how is HAP arranged in dentine

HAP is found on/in collagen fibrils of organic matrix


how are the collagen fibrils arranged in dentine

they run in PARALLEL to the pulpal surface


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


what is the difference between the primary and secondary curvatures

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


what is peri-tubular dentine

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


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

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


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


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


what are the different types of dentine

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


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


why does sclerotic dentine form

normal ageing process

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


why is irregular secondary dentine formed

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


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


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


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


what are calco-spherates

calcification spheres


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


which cells produce the dentine matrix



what is the mineralisation front

where the HAP is deposited.


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


what is found in un-mineralised pre-dentine

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


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