Week 7 Enamel Structure and Function Flashcards
(22 cards)
What is the inorganic/mineral content percentage of mature enamel?
96%
Mainly composed of calcium phosphate and hydroxyapatite, with other elements like strontium, magnesium, lead, sodium, carbonate, and fluoride possibly incorporated.
What is the organic material percentage in mature enamel?
1%
Includes tyrosine-rich amelogenin polypeptide (TRAP) and nonamelogenin proteins.
What is the water content percentage in mature enamel?
3%
What is the hardest substance in the human body?
Enamel
What color range does mature enamel typically exhibit?
Translucent light yellow to blue-gray
The color is affected by the underlying dentine.
What are enamel rods?
Prisms of tightly packed crystals running from outer surface to DEJ
No Tomes’ processes in initial enamel formation.
What is the thickness range of enamel rods?
Microscopic at CEJ to max ~3mm
How many ameloblasts form each enamel rod?
4 ameloblasts
What is the Dentino-Enamel Junction (DEJ)?
The junction where enamel meets dentine, scalloped under incisal edges and smooth elsewhere.
What is the appearance of the DEJ under SEM?
Concave surface toward enamel, convex toward dentine.
What are Striae of Retzius?
Incremental growth lines in enamel from growth disturbances.
Where are Striae of Retzius most prominent?
In post-natal permanent enamel
What is a large neonatal line?
An observable line at birth in enamel.
What do Perikymata represent?
Surface presentation of Striae of Retzius, appearing as grooves or furrows.
What are Imbrication lines?
Raised sections on the surface of enamel.
What do Enamel Tufts resemble?
Like geological faults from abrupt rod direction changes.
What are Enamel Lamellae?
Faults from the surface toward DEJ.
What are Enamel Spindles?
Odontoblastic processes that may cross the basement membrane into the ameloblast layer.
Are Enamel Tufts and Lamellae associated with caries risk?
No demonstrated weakness/caries risk.
What is Gnarled Enamel?
Enamel rods that appear intertwined under cusp tips.
True or False: Enamel is primarily composed of organic material.
False
Fill in the blank: Mature enamel is primarily made up of _______.
inorganic/mineral content
