Tooth Development Flashcards
what are the 3 embryonic layers
ectoderm
mesoderm
endoderm
(ectomesencyme / neural crest)
what embryonic layer are tooth structures formed from
enamel = ectoderm
pulp , dentine , cementum etc = ectomesenchyme
mandibulofacial dystosis
failure of neural crest cells to migrate
sees deformities of ears, eyes , cheekbones and chin
also known as treacher collins syndrome
at what age does the primary epithelial band develop and divide
around 6 weeks
divides to form the vestibular lamina (buccal surfaces) and the dental lamina (enamel organ)
describe the morphogenesis stage of tooth development (8-11wks)
dental lamina thickens into bud stage enamel organ - ectomesenchymal condensation appears around it this is the dental papilla
enamel organ develops into cap stage over papilla , enamel organ at this stage has 2 layers IEE and EEE
describe cytodifferentiation of tooth development (approx 14 wks)
bell stage enamel organ
has 4 layers - IEE, EEE , stratum intermedium and stellate reticulum
SR = innermost and contains energy for ameloblast function e.g sugar and glycogen
does differentiation occur across the enamel organ simultaneously
no , starts at apical regions first then trickles down to cervical
describe matrix secretion (approx 18wks)
dental papilla cells differentiate into ondontoblasts which lay down unmineralised dentine (pre dentine)
dentine formation induces IEE cells to diferentiate into ameloblasts
do all dental papilla cells differentiate into odontoblasts
no some differentiate into stem cells so that if dentine = damaged or ondontoblasts die they can form tertiary dentine
describe amelogenesis
1 - dentine induces IEE cells to differentiate into ameloblasts
2 - ameloblasts synthesise and secrete enamel matrix proteins (secretory phase)
3 - matrix proteins removed and mineral content increases (maturation)
4 - ameloblasts regress to form a protective ayer that is involved in tooth eruption
does amelogenesis occur simultaneously across the enamel organ
no - apical regions first
debris of mallasez
remnants of HERS , potential to develop into a cyst (ondontogeic cyst)
hertwigs epithelial root sheath
defines root shape
has 2 layers - IEE and EEE
what cells differentiate into cementoblasts
mesenchymal cells from the dental follicle when they come into contact with dentine
placodes
embryonic structures that give rise to various structures including hair follicles and teeth
hypohidrotic ectodermal dysplasia affects placed structures