Amelogenesis Flashcards
what is the percentage of mineral, matrix and water in enamel
mineral - 96%
matrix - 1-2%
water - 2%
why is there so little matrix in enamel
no structure in enamel
tenants of developmental proteins
doesnt contain collagen
what si the % of mineral, matrix and water in dentine
mineral - 70%
matrix - 20%
water - 10%
what si the % of mineral, matrix and water in cementum
mineral - 65%
matrix - 23%
water - 12%
what is the % of mineral, matrix and water in bone
mineral - 60%
matrix - 25%
water - 15%
what is enamel predominantly composed f
96% mineral - hydroxyapatite
what is enamel
mineralised epithelial product
what does the organic matrix contain
1-2%
enamel proteins (remnant of development)
not collagen
how much water in enamel
2%
when does enamel start t form
after dentine mineralises
what ar pre ameloblatss
long columnar epi cells tight bound tight junctional complex polarised nuc going to prod enamel organelles fro synthesis
what are some organelles used in synthesis
RER
golgi
sec vesicles
mito
when does enamel formation begin
when basal lamina disintegrates
when enamel formation begins what happens to the amelobast
retreats up and out the way
what shape change occurs to the amelobalt in enamel prodction
tomes process
prism shape of enamel
what si the final cue for amelogenesis to start
dentine formation
breakdown basal lamina
what is an ameloblast secrete
organic matrix - immediate partial mineralisation
what is the mineralised enamel matured by
influx of mineral ions - CA and phosphate
breakdowns dnremoval of organic matrix
what state is the organic matrix
amorphous gel
what is the enamel matrix composed of
amelogenins 90%
enamelling 20%
tuftelin
enzymes
what does enamels do
strongly bond to mineral
where is tuftelin confined to
ADJ
what re the enzymes for in the enamel matrix
as crystals expand the proteins have to be broken down
what are amelogenisn rich in
proline and glutamine
what features amelogeneisn cause good aggregation
hydrophobic
where are amelogensins found
spread throughout the developing enamel thickness
amelogenisns are thixotropic what does that mean
flows under certain conditions but remains fairly solid under conditions
changes under gentle pressure
what si the role of enamel proteins
nucleation of hydroxyapatite - epitactic matrix template
orientate and stablise crystal growth
broken down and lost during maturation
wha si the initial secretion of enamel like
virtually immediate mineralisation
15% mineral
65% water
20% proteins
what mineralisation takes place of he enamel after the intel secretion
rapid mineralisation 30% ‘immature/young’ enamel
maturation
further mineralisation 96%
what is maturation of enamel
thin crystals grow in thickness
what does maturation of enamel require
mineral ions IN
enamel matrix OUT
what does amelogenein do in maturation
flows under pressure - thixotropic
enzymes break down amelogensin
bulk breakdown products removed
what si the enamelling origin
produced by amelobasts or product of their breakdown
the matter that flows out ——-
amelogenins
the matrix that reminds ——
enamellin
bind tight hydroxyapatite
what happens to the tomes process in maturation
once most of enamel thickness laid down the tomes process is lost
what is the last formed enamel termed to be
aprismatic
no tomes process
what is formed when maturation is complete
enamel cuticle
what si the enamel cuticle secreted by
final ameloblast sec
how thick is the enamel cuticle
1 nanometres
when is reduced enamel epi produced
from when enamel formation is complete
what is reduced enamel epi derived from
reduced ameloblasts
remnants of enamel organ OEE
what si the reduced enamleepi attached to
the cuticle
what si the function of the reduced enamel epithelia
protection enamel surface from resorp, prevent cemtnum form
provide epi lined path for eruption
forms junctional epi
what it he fate of the REE
reduced enamel epi
fusion of basal lamina
cel death
junctional epi
