Tooth Development 2: Late Bell & Crown stages Flashcards
when is crown formation
14th week
when does crown formation take place
late bell stage
what is present at late bell stage
tooth germ
no hard tissue matrix laid at this point
when do cervical loop cells divide
bella nd crown stages
what does the division of cervical loop cells lead to
signal DP - IEE to mature elongate and polarise
signal IEE Dp cells to mature
DP = odontoblasts
IEE = ameloblasts
what does the odontoblasts form
predestine then dentine
what does the Amelobalsts gove rise to
enamel
what is some evidence of IEE cells synthesising enamel proteins
IEE cells more columnar and nucleus toward stratum intermedium - diff begins
where si the first place for predestine to be placed
at cusp
clos to enamel knot
how does the enamel knot affect cusp
growth factors
differneiation
once the dentine is made what happens
signal amelobasts to become sec and lay down enamel
what does epi do at cervical loop
proliferate
what is cervical loop largely imp for
root development
what are the cells found at the cervucal loop
IEE and ecto mesenchyme - yet to dif
what does the ecto mesenchyme signal
induces the limited proliferation of IEE
what signals from the ecto mesenchyme
BMP
WNT
FGF
what is sequence fro cervical loop diff
DP to IEE - control div
See to DP - induce pap cells to mature
DP to IEE - induce IEE to mature
dentine to IEE - dentine signals start of enamel sec
what does IEE diff into
ameloblasts
what do ameobalsts then do
signal to condense mesenchyme and these will start to diff into odontoblasts
what causes chines in matrix
laminin
CS-PG
enamel proteins
what is the process of maturing odontoblast
ameloblast diff first ectomesenchyme diff under layer ameloblast signal to diff layer nucleus move matrix laid down
before mineralisation of matrix takes place what happens
a lag phase before
what are some diff layers of dentine
mantle
granular
hyaline
what is matrix mostly prod by
collagen
what cells can be seen in developing tooth in late bell stage
dental papilla
functioning odontoblasts
pre-ameloblasts
- predestine formed = ameloblast= enamel
what is the lifecycle outline of an ameloblast
IEE start to diff reverse polarity - nun move enamel se cells maturation regress height
what is the stages in ameloblast life
pre sec sec transition maturation post maturation
what si the pre sec stage in ameloblast life
cytodiff
morphodiff
resorption basal lamina
epitomes interctaion
what is the sec stage in ameloblast life
initial layer enamel matrix sec initiation mineralisation degrade matrix
what is the transition stage in ameloblast stage
ameloblasts shorten die
reform basal lamina
cessation of matrix form
matrix degrade
what is the maturation stage of ameloblast
final degradation and withdraw matrix
crystal growth
what si the post maturation stage of ameloblast life
enamel organ degen
enamel cover established
eruption
expo oral cav
what is developing enamel
ameloblasts sec enamel
min and laid down
what is predentine
organic matrix that makes up dentine before it has calcified
what is in the organic matrix
collagens 1,3,5,6 proteoglycans - decor glycoproteins - osteonectin phosphoproteins - octeocalcin GF lipids
what is dentine
mineralised predestine
how is predestine mineralised to get dentine
1st layers matrix unmineralised when thick are min at same rate of formation
mineral depo
form primar dentien
what depo minerals in dentine form
odontoblasts
what controls dentine form
odontoblast control all
what is basic understanding of enamel
diff proteins form dentine
what are he two groups of enamel
amelogenins
enamelins
what are amelogenisn
multiple slice variants maj
what are enamelins
make up minority
when does morphogenesis
late cap stage and early bell stage
what is morphogenesis
rapid growth
cell divIEE
tooth shape determined
how is the shape determined
switch on and off sp transcription factors
whereis Shh found
dental epi
what does Shh do
increases cell proliferation, restriction of expression
when does reduced enamel epi from
when enamel formation complete
what is reduced enamel epi derived from
reduced ameloblasts
other remnants of enamel organ - OEE, SR, SI
what is the role of reduced enamel epi
protect enamel surface (resorption, cementum form)
epi lined path fro eruption
junctional epi
what si the secondary dental lamina
secessional dental laminae for developing successional teeth
what are some abnormalities which can occur at the inanition stage
anodontia
supernumerary teeth
micr/macrodontia
what is andontia
absence of teeth
what is supernumerary test
extra teeth
what is micro/macrodontia
miro - small teeth
macro - large teeth
what are some abdnomalites that can occur at cap stage
dens in dente
fusion and germination
what is dens in dentate
enamel organ invaginate into dental papilla
slits or gaps
what is fusion and germination
fusion- 2 roots - 1
germinate 1- 2/3 roots
