Enamel Flashcards
Describe enamel?
Hardest tissue in the body. Resists normal wear. Brittle so easy to fracture in a certain way. Covers tooth crown and varies in thickness (thickest at incised third).
Where does enamel develop from?
Tooth buds formed from epithelial tissue.
What do odontoblasts produce?
Dentine
What do ameloblasts produce?
Enamel
What establishes the shape of the enamel crystals?
Tomes process
How is enamel laid down?
From the amelo-dentinal junction outwards. Rods run from ADJ to surface.
What is the basic unit of enamel?
Enamel rod or prism.
Where is enamel the most mineralised in a tooth?
At the surface rather than deeper enamel as impurities are removed over time.
How are enamel rod’s arranged?
In a lock and key arrangement
What is the hydroxyapatite content of enamel?
95% weight (90% volume)
What is the water content of enamel?
4% weight (5-10% volume)
What is the organic matrix content of enamel?
1% weight (1-2% volume)
Name some molecules in the organic matrix?
Proteins, amelogenins, enamelins, peptides
Describe the surface of enamel?
It has a smooth surface but can have pits and fissures.
Describe the step-by-step formation of enamel?
Inner enamel epithelium cells differentiate into ameloblasts. Odontoblasts secrete the first layer of dentine which then causes ameloblasts to produce distal extension called the Tomes process. Initial enamel layer is mineralised immediately and doesn’t contain enamel rods as the times process develops but then rods are laid down.
