tooth development 1:)

Question 1

primary dentition

Answer 1

5 teeth
2 incisors
1 canine
2 motors
tooth morphology different between jaws

Question 2

permanent dentition

Answer 2

8 teeth
2 incisors 
1 canine
2 premolars
3 molars

Question 3

tooth development stages

Answer 3

initiation
morphodifferentiation
cytodifferentiation

Question 4

initiation stage

Answer 4

starts tooth formation

correct number in correct location in jaw

Question 5

morphodifferentiation stage

Answer 5

formation in correct shape

Question 6

cytodifferentiation stage

Answer 6

differentiation of cells to produce specific dental tissue

Question 7

what is the fist sign of tooth deelopment

Answer 7

primary epithelial band

thickened band of ectoderm along each dental arch

Question 8

when does the primary epithelial band appear

Answer 8

7 weeks post fertilisation after maxillary arch formed

Question 9

what gives rise to Md/Mx

Answer 9

pharyngeal arch

Question 10

what does the primary epithelial band do

Answer 10

tooth buds grow downwards into dental lamina to form buds
induces condensation of ectomesenchymal cells beneath the band
cells gather round and become denser due to signals from ecotoderm

Question 11

what happens after condensation of ectomesenchymal cells

Answer 11

epithelual band divides into dental laminar and vestibular lamina
continue to proliferate

the superficial cells of vestibular lamina degenerate to form a vestibule/sulcus

Question 12

what are signalling molcules and what are they expressed by

Answer 12

BMPs and FGFs

ectoderm

Question 13

what do the growth factors interact with

Answer 13

first arch ectomesenchyme to form the correct number of tooth buds in each quadrant

Question 14

chronological order from ectoderm formation

Answer 14

• Ectoderm thickens to give primary epithelial band
• Epithelium proliferates and grows into the lamina propria underneath
• Underneath the band are ecto-mesenchyme cells which condense (get thicker)
  originate from the neural crest
• Epithelial band divides and grows downwards into 2 sections
  Dental lamina
  Vestibular lamina:
  proliferates down, superfial cells then degenerate to form a vestibule/sulcus (gutter on lingual and buccal side)

Question 15

what does the epithelial band divide into

Answer 15

dental lamina

vestibular lamina

Question 16

where does the ectoderm originate from

Answer 16

facial processes

Question 17

what do mesenchymal cells originate from

Answer 17

neural crest

Question 18

what do the ectoderm and mesenchymal cells undergo

Answer 18

epithelial mesenchymal interactios to differentiate Into particular cells

Question 19

what does the oral ectoderm form

Answer 19

teeth in combination with first arch ectomesenchyme

Question 20

what is DLX gene coding

Answer 20

expression of homeobox genes at specific parts of the arch defines each type of tooth

Question 21

how does expression of genes affect the teeth

Answer 21

• each gene is expressed in a decreasing gradient from anterior to posterior i.e. 4 is more likely to be formed than 5

Question 22

what is it called when you introduce genes into a tissue

Answer 22

electroporation

Question 23

what is the effect of disruption to the initiation stage

Answer 23

anodontia
hyperdontia
hypodontia

Question 24

anodontia

Answer 24

no teeth are formed

Question 25

hypodontia

Answer 25

few teeth don't develop occurs at the end of expression domain commonly affects 8>5>3

Question 26

hyperdontita

Answer 26

extra teeth

Question 27

what are extra teeth known as

Answer 27

supernumerary

Question 28

what do supernumerary teeth look like

Answer 28

``` atypically shaped teeth (accessory) normal teeth (supplemental teeth) ```

Question 29

what happens after initiation

Answer 29

differentiation of oral ectodermal components into EO | ectomesenchymal components into dental papilla

Question 30

what differentiates into EO

Answer 30

oral ectoderm

Question 31

what differentiates into dental papilla

Answer 31

ectomesenchymal components

Question 32

what happens after differentiation into the EO ad DP

Answer 32

tooth bud grows into the CT Tip of EO grows around the DP now tooth germ not a bud

Question 33

how is determination of the shape of inidiviaul shape produced

Answer 33

selective division in the internal dental epithelial layer of EO

Question 34

morphodifferentation

Answer 34

internal layer of EO undergoes mitosis | leads to buckling of the future ADJ

Question 35

where do the signals for mitosis of the IDE of EO come from

Answer 35

DP and enamel knot

Question 36

what is and does the enamel knot do

Answer 36

tight group of cells refines signals from the DP controls selective mitosis of IDE

Question 37

what induces the enamel knot to form

Answer 37

BMP4

Question 38

what determines the basic tooth shape

Answer 38

dental papilla

Question 39

what separates the EO from the DP in recombination experiments

Answer 39

trypsin

Question 40

what singnals are sent from the DP and EK

Answer 40

BMPs 2 and 7 FGFs Wnt EK: SHH

Question 41

what happens after the shape of future junction of enamel and dentine is mapped out

Answer 41

EK disappears permanent tooth bud arises from side of EO of primary teeth dental follicle around whole tooth dental lamia disintegrates

Question 42

what are the layers in the EO

Answer 42

external dental epithelium stellate reticulum stratum intermedium internal dental epithelium

Question 43

stellate reticulium

Answer 43

largest area of the EO star shaped cells joined by desmosomes network, cells widley scattered

Question 44

stratum intermedium

Answer 44

sits on top of the IDE | squamous cells layered

Question 45

function of the EDE

Answer 45

regulates entry of nutrients | thin layer of cuboidal cells

Question 46

function of stellate reticulum

Answer 46

space packing with ECM nutrients to the IDE protects the tooth lots of Ca and phosphate needed for enamel

Question 47

function of stratum intermedium

Answer 47

essential for enamel formation

Question 48

function of IDE

Answer 48

differentates into amelolasts to form enamel

Question 49

what happens if morphodifferentaiton is no carried out correctly

Answer 49

bizzare shaped teeth

Question 50

permanent molar orgin

Answer 50

primary epithelial band grows posterially as jaws grow | three new buds arise