EX1; Amelogenesis Flashcards Preview

May14 Oral Histology > EX1; Amelogenesis > Flashcards

Flashcards in EX1; Amelogenesis Deck (46):
1

True or False
Amelogenesis occurs after dentinogenesis during the crown stage of odontogenesis

True

2

True or False
Dentin must be present for enamel to be formed

True

3

True or False
Ameloblasts must be present for dentinogenesis to occur even though denim must be present for enamel to be formed

True

4

What is the term describing the relationship between the formation of enamel (epithelium) and dentin (mesenchyme)

reciprocal induction

5

*What is unique regarding enamel and its mineralization phases

it does not have an unmineralized pre-enamel phase

6

What is formed via a two step process

enamel rods, sheath, and interrod substance

7

What is the first step in amelogenesis

secretion of an immature or partially mineralized enamel

8

What is the composition of the immature or partially mineralized enamel

70% organic and water
30% inorganic

9

Once the what of immature enamel is deposited does the second step occur

width

10

What is the second step of amelogenesis

significant influx of additional mineral coincident with the removal of organic material and water

11

What is the enamel described as during the second step

having secretory and maturative phases

12

*This specialized cell is the differentiated inner cells of the enamel organ

ameloblast

13

*This is located in the stratum intermedium layer of the enamel organ

alkaline phosphatase

14

*This is located in the dental follicle part of the tooth germ

rich blood supply; dentin is blocking the blood supply from the dental papillae

15

Cells in which area of the enamel organ are the first to differentiate into the ameloblasts

coronal most area; it then spreads cervically

16

What are the three main stages of amelogenesis

presecretory phase
secretory phase
postsecretory phase

17

What are the two phases of the presecretory phase

morphogenetic phase
histodifferentiation phase

18

What are the six phases of the secretory phase

inner immediately mineralized secretion
interrod substance secretion
rod secretion
maturation phase
outer immediately mineralized secretion
final ameloblast secretion phase

19

What is the phase of the postsecretory phase

protective phase; reduced enamel epithelium

20

What is the composition of the inner immediately mineralized secretion

ultra-thin inner rodless enamel layer

21

What is the mineralization content of the interred substance secretion and rod secretion

initially immature or partially mineralized

22

What occurs during the maturation phase of amelogenesis

removal of organic substances until 1%
removal of water until 3%
influx of mineral salts until 96%

23

What is the composition of the outer immediately mineralized secretion

ultra-thin outer rodless enamel layer

24

What is the non-mineralized portion of the final ameloblast secretion phase

basal lamina

25

What is located between the inner cells of the enamel organ and the peripheral cells of the dental papilla

clear or acellular layer

26

What cells are formed during the histodifferentiation phase

odontoblasts
ameloblasts (columnar epithelial cells)

27

True or False
The inner rodless (structureless) enamel immediately mineralizes upon secretion

True

28

During interred substance phase, what happens to the distal end of the ameloblasts

it changes from a smooth configuration to Tomes' process

29

What does Tomes' process secrete

the interrod substance that encircles the Tomes' process

30

What is the mineralization state of interrod substance

partially mineralized;
70% organic and water
30% inorganic

31

Tomes' pits are made of/surrounded by what

interrod substance

32

Tomes' process move out the pit as what occurs

as the ameloblast moves toward the future enamel surface

33

As the Tome's process withdraws itself from the pit, what is secreted into the pit

partially mineralized enamel rod

34

The presence of Tomes' processes and partially mineralized enamel indicate that the ameloblasts are in which phase

rod secretory

35

When the distal edge of the ameloblast is even (smooth) what does that mean

the ameloblast is resorbing or removing organic material and water

36

When the distal edge of the ameloblast is ruffled (rough) why does that mean

the ameloblast is secreting mineral salts (inorganic)

37

Maturation is complete when what occurs

the inorganic, organic, and water composition reaches the proper composition

38

When the distal ends of the ameloblast alternates from smooth to rough what does that mean for the Tomes' process

they are no longer present

39

True or False
The outer rodless enamel is secreted by Tomes' processes

False; it is not secreted by them (that's why it does not contain enamel rods)

40

*Which is the last mineralized secretion of ameloblasts

outer rodless enamel; it is not the final secretion

41

*What is the final ameloblast secretion phase

basal lamina

42

What composes the reduced enamel epithelium

remnant of enamel organ (4 layers) giving protection of enamel until tooth enters oral cavity

43

What does the reduced enamel epithelium become during emergence of the tooth into the oral cavity

junctional epithelium

44

What is used to attach the reduced enamel epithelium to the enamel surface

basal lamina

45

When is the initial mineralization for permanent teeth

birth to 9 years

46

When is the completed mineralization for permanent teeth

5 to 14 years