2/9/17 Colombo TEST #2 Enamel I

Question 1

T/F The underlying dentin support is critical for function of enamel

Answer 1

True

Question 2

Enamel is cellular or acellular?

Answer 2

-Acellular

Question 3

T/F Enamel is a brittle material

Answer 3

True

Question 4

What is the purpose of teeth?

Answer 4

-Survive repeated cyclical loading

Question 5

If your whole tooth was enamel would it break?

Answer 5

-Yes because enamel is brittle

Question 6

T/F Mature enamel is translucent with a range of colors

Answer 6

True

Question 7

Where is enamel the thickest at?

Answer 7

-The crown

Question 8

How thick is the enamel in mm?

Answer 8

2.5 mm

Question 9

What is enamel composed primarily of?

Answer 9

-Hydroxyapatite crystals

Question 10

What direction does enamel grow?

Answer 10

-Outwards

Question 11

What is another name for the protein component of enamel?

Answer 11

-The organic material at 1 %

Question 12

T/F Enamel has collagen

Answer 12

False

-It has not collagen

Question 13

What are four major enamel proteins?

Answer 13

• amelogenins
• ameloblastins
• enamelin
• tuftelin

Question 14

T/F Enamel crystals are closely packed, long, and ribbon like

Answer 14

True

Question 15

What are the two components of the crystals in enamel organization?

Answer 15

• Enamel rods

- Interrod enamel

Question 16

What is the formula for hydroxyapatite?

Answer 16

Ca5(PO4)3(OH)

Question 17

What two minerals that hydroxyapatite might incorporate are more vulnerable to acid attack?

Answer 17

• Carbonate

- Magnesium

Question 18

What mineral that hydroxyapatite might incorporate is less vulnerable to acid attack?

Answer 18

-Fluoride

Question 19

The inner enamel crystals are usually what instead of hydroxyapatite

Answer 19

-carbonatopatite

Question 20

What two components of hydroxyapatite an (CO3)2 replace?

Answer 20

• (PO4)3

- OH

Question 21

Where on the enamel do you typically find fluoride?

Answer 21

-Outer enamel

Question 22

What shape is each enamel crystal?

Answer 22

-Hexagonal

Question 23

What is an enamel rod?

Answer 23

-Cylindrical accumulation of enamel crystals, lined up along the long axis of the rod

Question 24

What direction do rods generally run?

Answer 24

-Perpendicular to the DEJ (pulp)

Question 25

T/F | A Rod contains multiple ameloblasts

Answer 25

False | -1 Ameloblasts = 1 Rod

Question 26

What is the rod sheath?

Answer 26

-A protein rich area of enamel that surrounds the rods

Question 27

How far around each rod do the rod sheaths run?

Answer 27

-3/4

Question 28

What do the rod sheaths separate?

Answer 28

-Rod and inter-rod enamel

Question 29

What are two rod sheath proteins?

Answer 29

- Ameloblastins | - Amelogenins

Question 30

If there are gaps of the rod sheath what are the enamel crystals continuous with?

Answer 30

-Interrod enamel

Question 31

T/F Interrod enamel has the same basic composition as rods, but are simply different in enamel crystal orientation

Answer 31

True

Question 32

What is the most vulnerable part of enamel to caries?

Answer 32

-Rod sheaths

Question 33

What are the three general phases of ameloblast maturation?

Answer 33

- Presecretory - Secretory - Mautration

Question 34

As the inner enamel epithelium develops what do they form?

Answer 34

-Ameloblasts

Question 35

What stimulates the ameloblasts to move?

Answer 35

-Pre-dentin formation by odontoblasts

Question 36

T/F AS enamel matures, organic component is reduce and mineralization increases

Answer 36

True

Question 37

What happens in the pre-secretory phase?

Answer 37

-Mature from pre-ameloblasts to ameloblasts

Question 38

What happens in the secretory phase?

Answer 38

-Deposition of enamel

Question 39

What happens in the maturation phase?

Answer 39

-Reduction of organic matrix, increase mineralization via ion transport

Question 40

How does the pre-dentin get exposed to the ameloblasts to initiate the ameloblast to lay down enamel?

Answer 40

-The basal lamina gets penetrated by cell projections to break it down

Question 41

Tome's process projects into the developing enamel and is the site of what?

Answer 41

-Secretory activity

Question 42

What effectively forms the Enamel Rod structure

Answer 42

-Tomes' Process

Question 43

Does the rod or interrod enamel form first?

Answer 43

-Inter-rod

Question 44

T/F The interrod forms a groove (pit) into which rods are formed

Answer 44

True

Question 45

What type of enamel cell do you get when you have infiltration and incorporation of calcium ions into crystals, get a lowered pH perhaps favors mineralization. Secretion of proteolytic enzymes?

Answer 45

Ruffled cells

Question 46

What type of enamel cell allows diffusion out of protein fragments out of enamel, which leak in between cells and laterally defuse through cell layer?

Answer 46

-Smooth cells

Question 47

What is the fate of the Enamel organ?

Answer 47

-Fusion of the IEE and OEE to form the reduced enamel epithelium

Question 48

What does the Reduced Enamel Epithelium fuse with to form a covering over the tooth?

Answer 48

-Oral epithelium

Question 49

What is the last secretory product of the ameloblasts?

Answer 49

-Primary enamel cuticle

Question 50

What is formed from remains of the REE merged with the oral epithelium and is removed due to mechanical forces?

Answer 50

-Secondary enamel cuticle