Enamel Flashcards
What is the difference between abrasion and attrition?
Abrasion is physical contact that can cause harm. Physical wear of teeth
Attrition is not a physiological wear but a pathological wear. The wear is not normal and is not part of regular behaviour
What are the qualities of enamel?
Hardest tissue of body
Resists abrasion
Supported by dentine
Brittle
Varies in thickness (Thicker at cusp or incisal edge of crown)
Translucent (light passes)
Transparency increases with mineralisation
What cell is enamel produced by?
ameloblasts
Is enamel formed outwards or inwards?
outwards from the amelo-dential junction (adj)
Where is the amelo-dentinal junction (ADJ)?
The point at which the enamel and dentine meet
How are crystallites deposited during tooth development?
at right angles to the ameloblast membrane
What is meant by the regional variations of enamel on a tooth?
Surface enamel is more mineralised and harder than deeper enamel
Hardness decreases from cusp tip/incisal edge to cervical region
therefore dental caries are more likely in the cervical region
What is the basic unit of enamel?
enamel rod/prism that runs from the ADJ to the surface of the tooth
What do enamel rods contain?
hydroxyapatite crystallites
What %’s make up enamel?
95% hydroxyapatite,
4% water
1% organic material (amelogenins, enamelins, peptides, amino acids)
What can be on the enamel surface?
pits and fissures or smooth
What are the incremental growth lines or bands seen in tooth enamel called?
striae of retzius
What are wave like ridges found on surface on enamel called?
perikymata or imbrication lines
What is the shape of an enamel rod unit?
keyhole
How does enamel differ from other calcified tissues?
no cells within it or on the surface
