Amelogenesis

Question 1

dentine, cementum and the alveolar bone are all mineralised connective tissue, what is enamel?

Answer 1

mineralised epithelial product

Question 2

Does enamel contain collagen?

Answer 2

No

Question 3

1-2% of enamel is organ matrix, what is this made up of?

Answer 3

enamel proteins (amelogenesis, enamelins and tuftelin)
enzymes

Question 4

when does enamel form in relation to dentine?

Answer 4

starts to form after dentine mineralises

Question 5

Enamel prism shape is governed by what?

Answer 5

tomes process and direction of migration of the ameloblast

Question 6

What is the final cue for onset of amelogenesis?

Answer 6

dentine formation
breakdown of the basal lamina

Question 7

Regions formed without a tomes process are aprimastic, where are these regions?

Answer 7

the 1st formed - innermost
last formed - outermost

Question 8

what are the roles of enamel proteins?

Answer 8

• aid nucleation of hydroxyapatite
• orientate and stabilise crystal growth

Question 9

what happens to enamel protiens during maturation?

Answer 9

they are broken down and lost

Question 10

Maturation of crystals requires what?

Answer 10

mineral ions in and enamel matrix out

Question 11

what viscosity is amelogenenin?

Answer 11

thixotropic

Question 12

what happens to amelogenin?

Answer 12

enzymes break down amelogenins and the bulk of break down products are removed

Question 13

what matrix proteins flows out and what matrix remains?

Answer 13

flows out = amelogenins
matrix that remains = enamelin

Question 14

once most of the enamel thickness is laid down, what is lost?

Answer 14

tomes process
- last formed enamel is aprismatic

Question 15

What is the final ameloblast secretion called?

Answer 15

the enamel cuticle

Question 16

What is the enamel cuticle?

Answer 16

formed when maturation is complete
it is the final ameloblast secretion
it is 1um thick - like a basal lamina
reduced enamel epithelium attaches to the enamel cuticle

Question 17

What is the reduced enamel epithelium dervived from?

Answer 17

• reduced ameloblasts
• other remnants of the enamel organ OEE

Question 18

what is the reduced enamel epithelium attached to?

Answer 18

the enamel cuticle

Question 19

What is the function of the reduced enamel epithelium?

Answer 19

• protection of enamel surface from resorption or prevention of cementum formation
• provide an epithelial lines pathway for eruption
• form initial junctional epithelium