-
________ is the hardest calcified tissue in the human body
Mature enamel
-
Enamel is _____ and _______
- avascular with no blood supply and no innervation
- nonvital and is incapable of renewing itself
-
Mature enamel is composed of
96% mineralized or inorganic material, 1% organic material and 3% water
-
The crystalline formation of mature enamel consists mainly of
- calcium hydroxyapatite,
- Ca10(PO4)6(OH)2
-
This calcium hydroxyapatite is similar to that found in lesser percentages in
bone, dentin and cementum
-
attrition
wearing away of tooth structure due to mastication
-
erosion
loss of tooth structure due to chemical action
-
Amelogenesis is the process of
enamel matrix formation that occurs during the apposition stage of tooth development
-
Enamel matrix is produced by
ameloblast cells
-
The enamel matrix is secreted from each ameloblast from its
Tomes’ process
-
Tomes’ process
is responsible for the way the enamel matrix is laid down
-
Enamel matrix is initially composed of
proteins and carbohydrates and only a small amount of calcium hydroxyapatite crystals
-
Enamel matrix is first formed in the
incisal or occlusal portion of the future crown near the forming DEJ
-
The ameloblast is specifically responsible for
maturation of enamel matrix into mature enamel
-
After the ameloblasts are finished with both enamel apposition and maturation, they become part of the _____ along with ______
- reduced enamel epithelium (REE),
- the other portions of the compressed enamel organ
-
posteruption maturation of enamel is due to
depositing of minerals such as fluoride and calcium from saliva into hypomineralized areas of enamel
-
_______ are the crystalline structure of enamel
Enamel rods or enamel prisms
-
Each enamel rod extends the width of the enamel from the
DEJ to the outer enamel surface
-
The enamel rods near the cusp tips or incisal edges, where the enamel is thickest, _______ compared with those near _______
-
The specific shape of each enamel rod is dictated by the
Tomes’ process of the ameloblast
-
Generally, each enamel rod is ________ and about 4 micrometers in diameter with a ________ in cross section which is divided into _______ portions
- cylindrical in shape
- keyhole or fish scale shape
- head and tail
-
Each enamel rod is actually produced by ___ ameloblasts
4
-
The dentinoenamel junction appears _______ on a cross section. The convex side of the DEJ is toward the ______ and the concave side is toward the _______
-
The DEJ allows
increased adherence between them, adding to the strength of the junction when the teeth function during mastication
-
The ______ appear as incremental lines
lines of Retzius
-
On transverse (cross sections)sections of enamel, the lines of Retzius appear as
concentric rings similar to the growth rings in a tree
-
The neonatal line is an __________ line of Retzius
accentuated incremental
-
The neonatal line marks the ________ and marks the __________
- stress or trauma experienced by the ameloblasts during birth
- border between the enamel matrix formed before and after birth
-
The neonatal line is found on all
primary teeth and in the larger cusps of the permanent first molars
-
Enamel spindles represents _______ and are due to ________
- short dentinal tubules near the DEJ
- odontoblasts that crossed the basement membrane before it mineralized into the DEJ
-
deepened pits and grooves are created when ameloblasts __________ causing _________
- “back into each other” during the apposition stage, cutting off each other’s source of nutrition
- incomplete maturation of enamel matrix making it weak or even absent in these areas
-
Remineralization is the
deposition of minerals into enamel from salivary minerals and fluoride
|
|
