Enamel

Question 1

What does cariogenic mean

Answer 1

Something that creates caries

Question 2

What are the functions/structure of enamel

Answer 2

-Hardest tissue in body​
-Resists abrasion​
-Brittle​
-Supported by dentine​
-Covers tooth crown​
-Varies in thickness​
-Translucent​
-Transparency increases with mineralisation​

Question 3

What is attrition

Answer 3

Attrition - the normal everyday wear of a tooth on incisal or occlusal surfaces
Erosion

Question 4

what is abrasion

Answer 4

the wear of a tooth over unusual activity, more pathological wear of tooth. Usually associated with grinding teeth

Question 5

Why must Enamel be supported

Answer 5

Never leave enamel unsupported as it will break much easier due to lack of dentine.

Question 6

Amelodentinal junction ADJ/EDJ

Answer 6

Junction where enamel and dentine meet

Question 7

Why does enamel have different thicknesses

Answer 7

-Surface enamel more mineralised and harder than deeper enamel​

-Hardness decreases from cusp tip/ incisal edge to cervical region​

-These properties have functional and clinical significance

Enamel on molars is thicker to withstand greater trauma due to chewing while incisors are primarily used for biting

Question 8

Make up of enamel

Answer 8

Hydroxyapatite (HA) ​
-95% weight (90% volume)​

Water ​
-4% weight (5-10% volume)​

Organic matrix ​
-1% weight; (1-2% volume)​
-Proteins: Amelogenins; enamelins, peptides, amino acids​
​

Question 9

What is erosion

Answer 9

The loss of tooth enamel caused by acid attack

Question 10

What are the dimensions of an enamel rod

Answer 10

5 micrometres x 2.5 mm

Question 11

How is rod structure determined (head + tail)

Answer 11

It is a result of variations in orientation of crystallites in different parts of the rod

Question 12

What regulates the nanomechanical properties of enamel

Answer 12

Minor protein component (Amelogenins; enamelins, peptides, amino acids)

Question 13

How are crytallites deposited

Answer 13

At right angles to ameloblast membrane

Question 14

When is crystallite orientation determined

Answer 14

During enamel formatiomn

Question 15

How does tooth whitening affect teeth (aside from whitening)

Answer 15

Removes organic content such as water and proteins which makes the enamel more brittle and at risk of fracture

Question 16

What are hydroxyappatite crystallites composed of

Answer 16

Calcium
Phosphate
OH

Question 17

Which material contains the largest HA crystallites

Answer 17

Enamel (greater than bon, cementum and dentine)

Question 18

What can magnesium carbonate and flouride substitute within hydroxyappatite

Answer 18

Ca - Mg
P - CO3
OH - F

Question 19

When is enamel more and less resistant to acid

Answer 19

High conc of CO3 in hydroxyappatite - Less resistant, more susceptible
High conc of Flouride in Hydroxyappatite - More resistant

Question 20

How are enamel rods arranged

Answer 20

Run in a sinusodial course (parallel)

Question 21

Where are Hunter-Schreger bands NOT present

Answer 21

Absent in outer enamel

Question 22

What is Gnarled enamel

Answer 22

Present at cusps, optical effect of intertwined enamel

Question 23

What causes neonatal lines (marks in enamel)

Answer 23

Trauma during intra-uterine life

Question 24

What are enamel tufts

Answer 24

hypomineralised regions due to residual matrix protein at prism boundaries

Question 25

What is enamel lamella

Answer 25

incomplete maturation of groups of prisms - ‘fault’ line extending through enamel thickness

Question 26

Where are enamel lamella and enamel tufts found

Answer 26

Enamel -dentine junction

Question 27

What are enamel spindles

Answer 27

Odontoblast processes extending into the enamel from the initial formation of the enamel

Question 28

How to differentiate between enamel and dentine

Answer 28

scalloping on enamel edge rods much thinner than dentine tubules

Question 29

The scalloping found on the enamel-dentine junction (EDJ) is more pronounced in the incisal and cuspal regions, compared with the side of the crown what is the advantage of this

Answer 29

The scalloped junction may provide a better mechanical union between enamel and dentine. There is increased surface of contact. Also, the interlocking shape may provide more resistance to lateral, shearing forces.

Question 30

What is the functional significance of gnarled enamel

Answer 30

The spatial arrangement of prisms may provide some resilience so that the enamel ‘gives’ very slightly during application of occlusal loads

Question 31

What are enamel spindles

Answer 31

They are thought to be formed by odontoblast processes that extend for a short distance into the internal enamel epithelium layer of the enamel organ

Question 32

What are enamel tufts

Answer 32

They represent regions of incompletely mineralised enamel matrix. They extend a short distance from the ADJ.

Question 33

What are enamel lamellae

Answer 33

They represent regions of incompletely mineralised enamel matrix. They extend through the full thickness of enamel

Question 34

What are dead tracts

Answer 34

These appear dark when viewed under transmitted light. The tubules are empty, and are sealed at the pulpal end by the deposition of tertiary dentine