Tooth Development Flashcards

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1
Q

what are the 3 embryonic layers

A

ectoderm
mesoderm
endoderm
(ectomesencyme / neural crest)

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2
Q

what embryonic layer are tooth structures formed from

A

enamel = ectoderm

pulp , dentine , cementum etc = ectomesenchyme

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3
Q

mandibulofacial dystosis

A

failure of neural crest cells to migrate
sees deformities of ears, eyes , cheekbones and chin
also known as treacher collins syndrome

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4
Q

at what age does the primary epithelial band develop and divide

A

around 6 weeks

divides to form the vestibular lamina (buccal surfaces) and the dental lamina (enamel organ)

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5
Q

describe the morphogenesis stage of tooth development (8-11wks)

A

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

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6
Q

describe cytodifferentiation of tooth development (approx 14 wks)

A

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

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7
Q

does differentiation occur across the enamel organ simultaneously

A

no , starts at apical regions first then trickles down to cervical

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8
Q

describe matrix secretion (approx 18wks)

A

dental papilla cells differentiate into ondontoblasts which lay down unmineralised dentine (pre dentine)
dentine formation induces IEE cells to diferentiate into ameloblasts

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9
Q

do all dental papilla cells differentiate into odontoblasts

A

no some differentiate into stem cells so that if dentine = damaged or ondontoblasts die they can form tertiary dentine

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10
Q

describe amelogenesis

A

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

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11
Q

does amelogenesis occur simultaneously across the enamel organ

A

no - apical regions first

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12
Q

debris of mallasez

A

remnants of HERS , potential to develop into a cyst (ondontogeic cyst)

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13
Q

hertwigs epithelial root sheath

A

defines root shape

has 2 layers - IEE and EEE

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14
Q

what cells differentiate into cementoblasts

A

mesenchymal cells from the dental follicle when they come into contact with dentine

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15
Q

placodes

A

embryonic structures that give rise to various structures including hair follicles and teeth
hypohidrotic ectodermal dysplasia affects placed structures

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16
Q

amelogenesis imperfecta

A

teeth = yellow/brown , small and very prone to damage
caused by a gene mutation that gives instructions for making enamelysin
hard to differentiate between enamel and dentine on radiographs due to low mineral content

17
Q

dentinogenesis imperfecta

A

dentine not developed or under mineralised
difficult to distinguish dentine and pulp on radiographs
teeth = blue/grey or yellow/brown and translucent

18
Q

gemination

A

tooth germ broken into 2

looks like 2 teeth in one

19
Q

fusion

A

teeth fuse together during development

20
Q

concrescence

A

2 teeth joined together at cementum

21
Q

tomes process

A

defines position of crystallites in enamel rod , one per rod

22
Q

mantle dentine

A

thin dentine layer closest to enamel that is formed first, has no tubules

23
Q

calcospherites

A

centres of dentine mineralisation

24
Q

meckels cartilage

A

cartilage from which the mandible is formed

25
Q

what do the palatal shelves form

A

secondary palate - part of the hard palate