Enamel

Question 1

What are the 2 main parts of the tooth

Answer 1

Crown and Root

Question 2

What is the junction between the crown and root called

Answer 2

Cement-enamel margin

Question 3

What are the 4 main parts of a human tooth

Answer 3

Enamel
Dentine
Cementum
Pulp

Question 4

Where is cementum found

Answer 4

Surrounds the root

Question 5

What is the margin between the enamel and dentine called

Answer 5

Enamel-dentine junction (EDJ)

Question 6

Where is the enamel the thinnest

Answer 6

At the cervial margin

Question 7

Name some properties of the enamel, including its elastic modulus

Answer 7

• high resistance to abrasion
• cannot repair itself
• low tensile strength
• brittle
• high modulus of elasticity (needs more force to stretch)

Question 8

What cells secrete enamel

Answer 8

Ameloblasts

Question 9

What does enamel consist of and how are these structure arranged

Answer 9

Hydroxyl apatite crystals arranged into prisms

Question 10

What is the structural formula for calcium hydroxyapatite crystals

Answer 10

Ca10(PO4)6(OH)2

Question 11

What shape are the crystallites of enamel in

Answer 11

Hexagonal

Question 12

Name some of the organic materials in the enamel

Answer 12

Basically the enamel proteins, amelogenin, enamelin and ameloblastin

Question 13

What direction do ameloblasts and odontoblasts secrete enamel and dentin in

Answer 13

Ameloblasts - moves outwards from the EDJ towards surface

Odontoblasts - moves inwards from the EDJ towards the pulp

Question 14

What is the rough shape of an enamel prism

Answer 14

Keyhole, head and a tail

Question 15

How many ameloblasts make on keyhole shaped prism

Answer 15

4

Question 16

What is unique about the surface enamel

Answer 16

Surface enamel is aprismatic

Question 17

How does each rod run relative to the DEJ

Answer 17

Runs perpendicular to a tangent at its origin at the DEJ as well as to its termination at the surface of the tooth

Question 18

What surround prism enamel

Answer 18

Inter-prism enamel

Question 19

How are cross striations formed

Answer 19

The appositional growth of enamel, one made a day

Question 20

What are retzius lines (striae or retzius)

Answer 20

Enamel timelines that form roughly after every 8 cross striations

Question 21

What are perikymata

Answer 21

Waves on the tooth surface formed by striae of retzius

Question 22

There is one accentuated striae of retzius, what is it called and why does it form

Answer 22

Neonatal line

The striae are affected by environmental stimulus, birth is a pretty huge stimulus

Question 23

What are hunter-schreger bands

Answer 23

Groups of enamel rods that cross over each other, kinda mad you’ll have to look at a pic, seen as alternating patterns of light and dark bands, these don’t relate to incremental growth

Question 24

What are enamel tufts

Answer 24

Hypocalcified areas between prisms that resemble tufts of grass

Question 25

What are enamel lamellae

Answer 25

Hypocalcified areas between prisms that are formed due to structural faults

Question 26

What are enamel spindles

Answer 26

Dentinal tubule ends trapped in enamel

Question 27

What can be the benefits of fluoride

Answer 27

When fluoride ion is incorporated into the hydroxyapatite crystals during mineralisation, the resulting enamel is more resistant to acid

Question 28

What risk is associated with fluoride and enamel

Answer 28

High levels of fluoride can disturb or kill ameloblasts to form malformed/mottled enamel

Question 29

What is enamel etching and why is it done

Answer 29

Removes prism/rods more than inter rods and increases the surface area for attachment of adhesive material