Tooth Development 3: Root Development Flashcards
what is the final goal of a functioning tooth
fulfil role in oral cav
on outside need enamel
inside need vital parts
what are the major parts of tooth needed for funtionin
enamel coronal dentine root dentine cementum pulp alveolar bone PDL
what is the crown aspect
enamel and dentine
what is the formation of enamel
epi to ameloblast to enamel
what is the formation of dentine
dental papilla to odontoblasts to dentine
what does formation of the crown require
reciprocal induction
epi signal required for initiation of dentine formation
what are the constituents of the root
dentine
cementum
what is the formation of the dentine
dental papilla to odontoblasts to dentine
what is the formation of cementum
dental follicle to cementoblasts to cementum
what are the dental papilla and dental follicle tissues
ectomensenchymal so need an epi initiating signal
what is root development driven by
henrtwigs epi root sheath
what is henrtwigs epi root sheath use in development of
apical dev of cervical loop region
OEE and IEE
define root morhophlogy
how does the HERS define root morphology
inductive influence on root morphogenesis and cementogenesis indirectly
what else done HERS do
proliferates - cell div apically disintegrates cervically (cell rest)
what is dental follicle origin
ectomesenchyme
- mesodermal origin
where is dental follicle
between enamel organ and bone
what does dental follicle give rise to
cementoblasts
fibroblasts
osteoblasts
what do cementoblasts do
form cementum
what do fibroblasts do
form PDL collagen fibres
what do osteoblasts do
forms alveolar bone - make socket in situ around tooth
doe the dental follicle affect gingival tissues
no
what are the 3 layers of dental follicle
inner investing - vascular become cemntoblasts
loose CT
outer - lines alveolus with bone
what does eruption of tooth need
anchoring
growth of root
more dentine and pre-dentine
what happens as tooth erupts
enamel matrix proteins binds to dentine and predentine form hyaline layer of hopewell smith
what GF’s does HERS produce
BMP4
EGF
TGF(beta)
what si the transcription factor used by HERS
Shh
what s the first stage of HERS action
induces odontoblast formation
what si the second stage of HERS action
pre dentine then dentine form
HERS basal lamina breaks down
when the hERS basal lamina breaks down what does this mean
epi cannot attach to dentine
what si the third stage of HERS action
HERS cells secrete enamel matrix proteins (amelogenins) on predestine surface
what does the action of amelogenins mean
lay down enamel
mineralised
ameloblast attachment is prevented
hyaline layer formed
what is the fourth stage of HERS action
enamel matrix proteins mineralise to forth hyaline layer of hopewell smith
what is the fifth stage of HERS action
HERS disiitnegrates
no basal lamina
lack of ability to bind to hyaline layer
what is the sixth stage of HERS action
induction of follicle cells
- migrate to root surface and form cementoblasts
how is the induction of the follicle cells induced
GF’s
how can the follicle cells attach
mesenchymal origin so don’t need basal lamia to watch as interact with matrix
what is the seventh stage of HERS action
cementoblasts secret cementum matrix and retreat outwards
what is cementum
collagen 1 fibronectin osteocalcin osteopontin DMP1 Cementum matrix protein GF's - BMP2/4/7
what sit he eight stage of HERS action
cementum matrix mineralises
entrapping PDL fibres
what does the PDL entrapment mean for he tooth
extra strength
what are the PDL fibres
collagen
what sit he ninth stage of HERS action
remnants of HERS from cell rests to malassez in PDL - cystic potential
what si the cel fate HERS
with age num of cell rests decrease (props apoptosis) also EMT
what is thought of th cell rests action
go through mesenchymal transisiton
in the developing area of the roots what is found
cementum hyaline layer dentine predentine HERS cells odontoblasts cemntoblasts rafts epi cels
what are developing cells proliferating into
dental papilla
where is the hyaline layer
between dentine and predentine
what is the hyaline layer
highlymineralised
10uM thick sp size
what si the hyaline layer origin
matrix from
epi cells - enamel matrix protein
ectomesenchymal cells
what is the ole of the hyaline layer
induced cementoblasts formation
cements cementum to tooth
what is cementogenesis
form cementum
calcified CT cover roots
what are the two types of cementogenesis
acellular primary
cellular secondary
what are cementoblalss derived form
dental follicle
what do cememntoblasts do
depo matrix - precementum
collagen
what is acellular slow to do
increase thickness
what collagen type is most abundant in PDL
collagen 1
what si the alveolus
bone that forms around the tooth germ
what doe the alveolus come form
outerlayerof mesenchyme
when the tooth erupts what happens to the alveolus
resorption of bone to allow tooth thorugh
what do HERS cells cause osteogenically
differetiaion form bone cells
what are gubernacular canals
area between apex of deciduous and permanent tooth germ
CT though the alveolus bone
where is PDL
between cementum and alveolar bone
what does he PDL do
support the tooth
what doe thePDL comtain
sp CT that attach unrealised tissue covering root dentine to alv bone
what does PDL prod
masses of collagen fibres and hyalouronan
GF’s - TGF(beta) EGF
whataresome collagen fibres found around the tooth
horizontal alveolar crest circumferential dentine-gingival trans-septal inter-radicular oblique apical
what is theintermedivte plexus
controversy
between bone and dentine collagen fibres
what are the number of roots controlled by
controlled by DP
sub division and prolif make extra roots under FGF’s
