Enamel Flashcards
What forms enamel?
Ameloblasts
What are 5 key features of enamel?
- Hardest biological tissue
- Abrasion resistance is high
- Low tensile strength and brittle
- Cannot be repaired or replaced
- Avascular
Where is enamel thickest on the tooth?
Over cusps and incisal edges
Where is the enamel thinnest on the tooth?
Cervical margin
What forms the mineral component of enamel?
Calcium hydroxyapatite crystals
What 2 things form the organic component of enamel?
- Amelogenins
2. Non-amelogenins
What is the basic structural unit of enamel?
Enamel rods
What forms enamel rods or interrod enamel?
Crystallites
Where do enamel rods run?
Enamel-dentin junction to the surface of the tooth
What is the main difference between rod and interrod composition?
Interrod crystals deviate 40° - 60° from crystals found in rods
What pattern are enamel rods found in?
Keyhole pattern
What is the name of the banding pattern found in enamel?
Hunter-Schraeger bands
What are 2 functions of Hunter-Schraeger bands?
- Strengthen enamel
2. Prevent cracks from propagating through tooth
How do Hunter-Schraeger bands arise?
10-13 layers of rods follow the same direction but blocks above and below follow paths in different directions
What 3 things cause incremental lines to appear?
- Changes in enamel secretory rhythm
- Chemical composition of enamel
- Position of the developing enamel front