Enamel Flashcards
What are the 2 main parts of the tooth
Crown and Root
What is the junction between the crown and root called
Cement-enamel margin
What are the 4 main parts of a human tooth
Enamel
Dentine
Cementum
Pulp
Where is cementum found
Surrounds the root
What is the margin between the enamel and dentine called
Enamel-dentine junction (EDJ)
Where is the enamel the thinnest
At the cervial margin
Name some properties of the enamel, including its elastic modulus
- high resistance to abrasion
- cannot repair itself
- low tensile strength
- brittle
- high modulus of elasticity (needs more force to stretch)
What cells secrete enamel
Ameloblasts
What does enamel consist of and how are these structure arranged
Hydroxyl apatite crystals arranged into prisms
What is the structural formula for calcium hydroxyapatite crystals
Ca10(PO4)6(OH)2
What shape are the crystallites of enamel in
Hexagonal
Name some of the organic materials in the enamel
Basically the enamel proteins, amelogenin, enamelin and ameloblastin
What direction do ameloblasts and odontoblasts secrete enamel and dentin in
Ameloblasts - moves outwards from the EDJ towards surface
Odontoblasts - moves inwards from the EDJ towards the pulp
What is the rough shape of an enamel prism
Keyhole, head and a tail
How many ameloblasts make on keyhole shaped prism
4
What is unique about the surface enamel
Surface enamel is aprismatic
How does each rod run relative to the DEJ
Runs perpendicular to a tangent at its origin at the DEJ as well as to its termination at the surface of the tooth
What surround prism enamel
Inter-prism enamel
How are cross striations formed
The appositional growth of enamel, one made a day
What are retzius lines (striae or retzius)
Enamel timelines that form roughly after every 8 cross striations
What are perikymata
Waves on the tooth surface formed by striae of retzius
There is one accentuated striae of retzius, what is it called and why does it form
Neonatal line
The striae are affected by environmental stimulus, birth is a pretty huge stimulus
What are hunter-schreger bands
Groups of enamel rods that cross over each other, kinda mad you’ll have to look at a pic, seen as alternating patterns of light and dark bands, these don’t relate to incremental growth
What are enamel tufts
Hypocalcified areas between prisms that resemble tufts of grass
What are enamel lamellae
Hypocalcified areas between prisms that are formed due to structural faults
What are enamel spindles
Dentinal tubule ends trapped in enamel
What can be the benefits of fluoride
When fluoride ion is incorporated into the hydroxyapatite crystals during mineralisation, the resulting enamel is more resistant to acid
What risk is associated with fluoride and enamel
High levels of fluoride can disturb or kill ameloblasts to form malformed/mottled enamel
What is enamel etching and why is it done
Removes prism/rods more than inter rods and increases the surface area for attachment of adhesive material
