EX1; Amelogenesis

Question 1

True or False

Amelogenesis occurs after dentinogenesis during the crown stage of odontogenesis

Answer 1

True

Question 2

True or False

Dentin must be present for enamel to be formed

Answer 2

True

Question 3

True or False

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

Answer 3

True

Question 4

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

Answer 4

reciprocal induction

Question 5

*What is unique regarding enamel and its mineralization phases

Answer 5

it does not have an unmineralized pre-enamel phase

Question 6

What is formed via a two step process

Answer 6

enamel rods, sheath, and interrod substance

Question 7

What is the first step in amelogenesis

Answer 7

secretion of an immature or partially mineralized enamel

Question 8

What is the composition of the immature or partially mineralized enamel

Answer 8

70% organic and water

30% inorganic

Question 9

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

Answer 9

width

Question 10

What is the second step of amelogenesis

Answer 10

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

Question 11

What is the enamel described as during the second step

Answer 11

having secretory and maturative phases

Question 12

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

Answer 12

ameloblast

Question 13

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

Answer 13

alkaline phosphatase

Question 14

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

Answer 14

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

Question 15

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

Answer 15

coronal most area; it then spreads cervically

Question 16

What are the three main stages of amelogenesis

Answer 16

presecretory phase
secretory phase
postsecretory phase

Question 17

What are the two phases of the presecretory phase

Answer 17

morphogenetic phase

histodifferentiation phase

Question 18

What are the six phases of the secretory phase

Answer 18

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

Question 19

What is the phase of the postsecretory phase

Answer 19

protective phase; reduced enamel epithelium

Question 20

What is the composition of the inner immediately mineralized secretion

Answer 20

ultra-thin inner rodless enamel layer

Question 21

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

Answer 21

initially immature or partially mineralized

Question 22

What occurs during the maturation phase of amelogenesis

Answer 22

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

Question 23

What is the composition of the outer immediately mineralized secretion

Answer 23

ultra-thin outer rodless enamel layer

Question 24

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

Answer 24

basal lamina

Question 25

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

Answer 25

clear or acellular layer

Question 26

What cells are formed during the histodifferentiation phase

Answer 26

``` odontoblasts ameloblasts (columnar epithelial cells) ```

Question 27

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

Answer 27

True

Question 28

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

Answer 28

it changes from a smooth configuration to Tomes' process

Question 29

What does Tomes' process secrete

Answer 29

the interrod substance that encircles the Tomes' process

Question 30

What is the mineralization state of interrod substance

Answer 30

partially mineralized; 70% organic and water 30% inorganic

Question 31

Tomes' pits are made of/surrounded by what

Answer 31

interrod substance

Question 32

Tomes' process move out the pit as what occurs

Answer 32

as the ameloblast moves toward the future enamel surface

Question 33

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

Answer 33

partially mineralized enamel rod

Question 34

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

Answer 34

rod secretory

Question 35

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

Answer 35

the ameloblast is resorbing or removing organic material and water

Question 36

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

Answer 36

the ameloblast is secreting mineral salts (inorganic)

Question 37

Maturation is complete when what occurs

Answer 37

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

Question 38

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

Answer 38

they are no longer present

Question 39

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

Answer 39

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

Question 40

*Which is the last mineralized secretion of ameloblasts

Answer 40

outer rodless enamel; it is not the final secretion

Question 41

*What is the final ameloblast secretion phase

Answer 41

basal lamina

Question 42

What composes the reduced enamel epithelium

Answer 42

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

Question 43

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

Answer 43

junctional epithelium

Question 44

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

Answer 44

basal lamina

Question 45

When is the initial mineralization for permanent teeth

Answer 45

birth to 9 years

Question 46

When is the completed mineralization for permanent teeth

Answer 46

5 to 14 years