tooth development 2:) Flashcards
tooth stages
initiation
morphodifferentiation
cytodifferentiation
what is cytodiffernetiation
differentiation of cells to produce specialised dental tissues
what happens during cytodifferentiation after growth of correct shaped tooth germ
IDE differentiated into ameloblasts
dental papilla differentiates into odontological blasts
how does the IDE differentiate into ameloblasts
sequentially from the tip moving down towards IDE
what do ameloblasts and odontoblasts produce
enamel
odontoblasts
where is predestine found
adjacent to odontoblast cells
what is the junction between enamel and dentine tissue
amelodentinal junction
steps of cytodifferentiation
IDE undergoes selective mitosis in the morphodifferentaition stage - ID induces dental papilla to form odontoblasts
odontoblasts secrete dentine and induce the IDE to differentiate into ameloblasts (upper parts first)
ameloblasts move outwards in the enamel organ to produce enamel tissue
dentine forms via an inwards direction
dental papilla reminas in the middle to form the pulp
where does cytodifferentaiotn occur first in incisors and molrs
incisor
- underneath what becomes incised edge
molars
- underneath what becomes cusp tips
root formation stages
induction
morphodifferentaion
cytodifferentation
- required to give number, shape length and dentine/dementum structure
when does root formation stard
as crown formation is completing
what is the situation once crown has almost completed
EO is reduced in size
two layers of EO are continuous at the cervical loop (where the cervix of the tooth is)
what happens to the two layer of the EO once it is reduced in size
two layers combine to form the epithelial root sheath
- grow down between the dental papilla and dental follicle
- maps out the shape and length of roots
what does each root sheath form and for multi rooted teeth
form a cylinder around the dental papilla
MRT
- root sheath separated into 2/3 individual root sheaths
where does the root start to divide
furcation
what does the root sheath induce
differentiation of odontoblasts from dental papilla
- cell division occurs at the growing tip to continue elongation of root sheath until root length is established
what happens to the root sheath during cell divison
root sheath extends and stretches into a network of cells
allows dental follicle to contact dentine through gaps between the cells
islets of cells are epithelial cell rests
what is dentine and dentine follicle derived from
ecotomesenchyme
what does the root sheath secrete and why
hyaline layer
- provides inductive effect on the dental follicle lying outside
what does the hyaline layer do
induces dental papilla to differentiate into
1) cementomalsts to form cementum
2) fibroblasts to form collagenous bundles of PDL
