Midterms

Question 1

What is the most highly mineralized extracellular matrix?

Answer 1

Enamel

Question 2

What us the composition and its percentage of Enamel?

Answer 2

Inorganic - 96-98%
Organic - 2-4%

Question 3

What is the color of enamel?

Answer 3

White to grayish white or translucent

Question 4

What is the texture of enamel?

Answer 4

Smooth and glossy

Question 5

What is the specific gravity of enamel?

Answer 5

2.8 specific gravity

Question 6

What kind of inorganic mineral has enamel?

Answer 6

Hydroxyapatite : Crystalline calcium phosphate

Question 7

What are the substitued group for inorganic mineral of enamel?

Answer 7

Fluorine and chlorine

Question 8

For the organic what are the types of it in enamel?

Answer 8

Amelogenins
Ameloblastin
Enamelin

Question 9

Amelogenins have how many percent?

Answer 9

90%

Question 10

What inhibits the lateral growth of hydroxyapatite?

Answer 10

Amelogenins

Question 11

What are the hydrophobic proteins of organic amelogenins?

Answer 11

Proline, Histidine, and Glutamine

Question 12

What kind of loss function in amelogenins?

Answer 12

Thin hypoplastic enamel without enamel rods

Question 13

What are the 2 types of Non-amelogenins?

Answer 13

Ameloblastin and enamelin

Question 14

How many percent is non-amelogenins?

Answer 14

10%

Question 15

It is found mostly in newly formed enamel?

Answer 15

Ameloblastin

Question 16

Size of ameloblastin

Answer 16

2.5 larger than amelogenin

Question 17

What is the loss of function of ameloblastin?

Answer 17

Amelogenesis aborts

Question 18

It is the largest and least abundant?

Answer 18

Enamelin

Question 19

Lost of function of enamelin?

Answer 19

No defined enamel layer

Question 20

What are the structure of enamel?

Answer 20

Enamel rods
Enamel rod sheath
Interrod enamel

Question 21

It is a fundamental organizational unit of mammalian enamel?

Answer 21

Enamel rods

Question 22

What is made from and shape of enamel rods?

Answer 22

Made from long closely pack ribbon like crystals
Shape is cylindrical

Question 23

It surrounds each rod what do you call that structure of enamel?

Answer 23

Interrod enamel

Question 24

A boundary between rod and interrod enamel
Also less crystal thats why it is more acid resistance?

Answer 24

Enamel rod sheath

Question 25

What is the appearance of enamel rod sheath?

Answer 25

Fish scale appearance

Question 26

-Growth lines
-run from the DEJ in an oblique direction to the occlusal surface (horseshoe shaped over the dentinal core)
-In cross-section, appears concentric rings

Answer 26

Striae of Retzius

Question 27

-occurs near the cervical & incisal/occlusal areas
-intertwining of groups of enamel rods following a curving irregular path toward the tooth surface
- “TWISTED”

Answer 27

Gnarled enamel

Question 28

-alternating constrictions & expansions of the rods
-cross striations occurring at a rate of about 4μm/ day

Answer 28

Transversed striations

Question 29

-optical phenomenon due to the change in direction of enamel rods
-alternating light & dark bands —› appear as dark & light zones

Answer 29

Bands of hunter-shreger

Question 30

-dark band
-rods cut transversely perpendicular to their long axes

Answer 30

Diazone

Question 31

-light bands
-rods cut parallel to their long axes

Answer 31

Parazone

Question 32

looks like grass
-Hypomineralized enamel from the DEJ about 1/5 to 1/3 the thickness of enamel

Answer 32

Enamel tufts

Question 33

-visible cracks on the surface of enamel
-develop during enamel formation or during function.

Answer 33

Enamel lamellae

Question 34

-short, straight, thin, dark structures extending for short distances into enamel
-Irregular, spiral or club shaped
-Causes hypersensitivity along the DEJ
-Ends of odontoblastic processes

Answer 34

Enamel spindle

Question 35

-Scalloped in cross-section
-This type of microlinkage increases the attachment of enamel to dentin

Answer 35

Dentino-enamel junction