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Flashcards in Amelogenesis Deck (35):
1

What is amelogenesis

Formation of enamel

2

Enamel definition

Composite biological mineral with apatite crystals oriented in a complex three-dimensional pattern

3

When does amelogenesis occur?

After dentinogenesis begins in the crown stage of odontogenesis

4

What must be present for enamel to form?

Dentin

5

What is required for odontoblast to be differentiated?

Ameloblasts

6

What makes enamel unique compared to the other 3 mineralized tissues?

It does not have an unmineralized preenamel stage

7

What does enamel formation require?

1. Specialized cells (ameloblasts)
2. Alkaline phosphatase
3. Rich blood supply

8

Where is alkaline phosphatase located?

Stratum Intermedium layer of enamel organ

9

What is the first area of the tooth to develop enamel?

The coronal-most area of the inner layer of the enamel organ
The process continues apically toward the cervical loop

10

What are the stages of enamel formation?

1) Presecratory stage
2) Secretory stage
3) Postsecratory stage

11

What are the phases of the Presecratory stage?

Morphogenetic stage
Histodifferentiation phase

12

What are the phases of the Secretory stage?

Inner mineralized phase
Interrod substance secretion phase
Rodsecretion phase
Maturation phase
Outer immediately mineralization secretion
Final Ameloblast secretion phase

13

What are the phases of the postsecretory stage?

Protective phase

14

What occurs during the Morphogenetic phase?

Clear or acellular layer is seen between the inner cells of the enamel organ and the peripheral cells of the dental papilla

15

What occurs during the Histodifferentiation phase?

Ameloblasts extend down to clear layer, touch the peripheral cells of the papilla, and then grown the other way
When the ameloblasts touch the peripheral cells, it causes them to differentiate to odontoblasts

16

Do ameloblasts or odontoblasts secrete firsts?

Odontoblasts

17

What occurs during the inner mineralized

Inner rodless enamel is secreted and immediately mineralized
It is secreted on top of the DEJ
There are no rods here, but it is still enamel - it is so the rods do not touch dentin
Distal portions of ameloblasts are smooth

18

What occurs during the Interrod substance secretion phase?

Distal portions of ameloblasts go form smooth to a Tomes' process
Tomes' processes of adjacent ameloblasts secreted the interrod substance that secretes encircles Tomes' processes

19

Tomes' pit

The space that is initially occupied by Tomes' processes until the ameloblasts move

20

What is the structure of interrod substance when it is secreted?

Partially mineralized

21

What is the content of partially mineralized substances?

70% organic and water
30% inorganic

22

What are the walls of Tomes' pits made of?

Interrod substance

23

What occurs during Rod secretory phase?

Tomes' process moves out of the pit as the ameloblast moves toward the future enamel surface
As the process withdraws, it secretes partially mineralized rods into the pits
This continues until the length of the immature interrod substance and rod is reached

24

What occurs before the maturation phase begins?

The rod and interrod enamel is partially mineralized and the distal end of the ameloblast is Tomes' process

25

What occurs during the maturation phase?

The distal end of the ameloblasts alternates between an even/smooth edge and an uneven/ruffled edge

26

What is occurring when the ameloblast distal edge is even/smooth?

The ameloblast is resorbing or removing organic material and water

27

What is occurring when the ameloblast distal edge is ruffled/uneven?

The ameloblast is secreting mineral salts (inorganic substances)

28

When is the maturation phase complete?

Inorganic material reaches 96%
Organic material reaches 1%
Water reaches 3%

29

What occurs during outer mineralized phase?

The outer rodless enamel is secreted

30

T/F - the outer rodless enamel is the final secretion of an ameloblast?

False - it is the last mineralized secretion, but not the last secretion

31

What occurs in the final ameloblast secretion phase?

The basal lamina is secreted by the ameloblasts

32

Basal lamina

Final secretion by ameloblasts
Nonmineralized
Stuck to the outer rodless enamel

33

What occurs in the Protective phase?

The four cell layers of the enamel organ come together to form the reduced enamel epithelium

34

Reduced enamel epithelium

Protective layer of the enamel that becomes the junctional epithelium during the emergence of the tooth into the oral cavity
Attached to the enamel by the basal lamina

35

How long does maturation phase take for permanent teeth?

5 years