Enamel

Question 1

What is it?

Answer 1

highly calcified, protective outer covering of the crown + is the hardest substance in the body.
its properties + microscopic structures:

Question 2

1.

Answer 2

made up of 96% mineral crystals (inorganic) arranged as prisms in an organic matrix called the inter prismatic substance
the main mineral crystals are calcium hydroxyapatite

Question 3

2.

Answer 3

The prisms lie at right angles to the junction with the next tooth layer (dentine) the junction between these two layers is called the ameldodentinal junction (ADJ)

Question 4

3.

Answer 4

Enamel is formed before tooth eruption by the ameloblast cells which lie at the ADJ

Question 5

4.

Answer 5

it contains no nerves nor blood vessels + therefore cannot experience any sensation
it is a non-living tissue which cannot grow or repair itself, so progressive damage called by injury or decay is permanent

Question 6

5.

Answer 6

It can remineralise its surface after acid attack by taking in minerals from saliva + oral health products such as toothpaste + mouthwash

Question 7

6.

Answer 7

the crystal structure can be altered without undergoing aid attack, by exchange of hydroxyl ions in the hydroxyapatite with fluoride, to form fluorapatite crystals - these make enamel surface harder + more resistant to acid attack

Question 8

7.

Answer 8

the enamel layer is thicker over the biting surface of the tooth (occlusal or incisal edge) + thinnest at neck of the tooth (cervical margin)

Question 9

8.

Answer 9

It is translucent, so the shade of a tooth is determined by the colour of the underlying dentine