Histology Of Enamel

Question 1

What is the composition of enamel

Answer 1

Mostly inorganic 96% hydroxyapatite and organic 4% collagen, water and proteins

Question 2

What are the structures of enamel

Answer 2

•Enamel rods (prisms)
•Interrods
•Crystallites (calcium hydroxyapatite)
•Link to amelogenesis
•Incremental lines
•Prismless enamel (rod-less)
•Dento-enamel junction and microscopic features

Question 3

Enamel rods

Answer 3

• Each Enamel rod is formed by 1 ameloblast during amelogenesis, pattern of amelogenesis results in incremental lines
• The enamel rods have a head and a tail
• The rods run perpendicular from the DEJ

Question 4

Enamel crystallises

Answer 4

These are hydroxyapatite packed inside the keyhole of a rod, to strengthen enamel

Question 5

Enamel lamella

Answer 5

Cracks in the enamel due to stress (temperature change) drinking hot and cold drinks (prone to cavities)
Can reach the DEJ

Question 6

Enamel spindles

Answer 6

Extension of dentine tubules in enamel, odontoblasts cells are in the spindles and can cause sensitivity sometimes, they’re much shorter than tufts

Question 7

Incremental lines

Answer 7

This is a surface characteristic, it’s a pattern of amelogenesis, marked when newly erupted and go away overtime (perkymata) in the picture

Question 8

‘Prismless’ enamel

Answer 8

There are no enamel rods (prisms) in some areas of enamel meaning It is 30 microns wide at the surface, highly radio-opaque, harder and less soluable

Question 9

What are the functions of enamel

Answer 9

Eating, protection, ion exchange, smile, inability to repair of feel injury

Question 10

What is enamel prone to

Answer 10

Tooth wear: abrasion, attrition, erosion

Question 11

What is hyperplasia

Answer 11

It’s an abnormality in enamel, defects during amelogenesis