Enamel Flashcards
Enamel the specialized covering over teeth
developed from _______
epithelium
Cells that produce enamel, ________, are removed during tooth eruption
ameloblasts
enamel is translucent, has a light yellow to grey-white color and is very thin about _______
2.5 mm
enamel is highly mineralized with about ______ mineral, ______ water, and ______ organic material
96%, 3%, 1%
enamel is hard and brittle where ______ is a necessary base or else enamel can fracture
dentin
enamel is made of inorganic material which includes ________ or ________ and organic material which includes ______ and ______
crystalline calcium, carbonated phosphate (hydroxyapatite), tyrosine-rich amelogenin polypeptide (TRAP), nonamelogenin proteins
The basic unit of enamel is the ________ and surrounding the _____ is the ________
enamel rod, rod, inter-rod region
Enamel and rods contain long crystals of about ______ wide and _______ long
60 – 70 nm, >100 μm
Hydroxyapatite crystals run in ________ in rod and interrod
different directions
Crystals thicken as enamel matures with increasing ______ content
mineral
As enamel grows the crystals become
_______, which is based on the _______ structure
hexagonal, calcium phosphate
ions can be incorporated into the extracellular matrix of the enamel crystals and these ions include ______, _______, ______, and _______
fluoride, magnesium, strontium, lead
____ can dissolve crystals
acid
the region between the interrod region and
the rod is the _________ where more organic
material is found
rod sheath
Organic matrix remains in the _______ as enamel matures aka as enamel matures the organic material is removed and most remains only in the ________
rod sheath, rod sheath
amelogenesis is the formation of ______
enamel
the 3 major phases of amelogenesis include the ______, ______ and ______ phases
presecretory, secretory, maturation
the presecretory phase begins in _______ when cells differentiate and become protein secreting cells called ________ which undergo changes in morphology with development
inner enamel epithelium, ameloblasts,
in the secretory phase ameloblasts make and organize ______
enamel
in the maturation phase the organic material is _______ and ions are transported for ______ deposition
removed, mineral
during the secretory stage there is around _______ mineralized enamel, _____ water and _____ protein
29% , 5%, 66%
during maturation phase there is between ______ mineralized enamel, _____ water and around _____ protein
93-95%, 1-3%, 4%
Internal enamel epithelium induces the
underlying dental papilla cells to become
_______, where the ________ then form dentin that in turn induces the internal enamel epithelium (presecretory ameloblasts) to become secretory ameloblasts that form ______
ondotoblasts, Odontoblasts, enamel
the 7 stages of Ameloblast differentiation
and morphogenesis:
1. Morphogenetic stage (_______)
2. Histodifferentiation stage (________)
3. Initial secretory stage
4. Secretory stage (__________)
5. Early Maturation stage (________)
6. Late Maturation stage (_________) During 5-6 enamel water and organic content decreases
7. Protective stage (lasts until
tooth eruption when cells are
shed)
cuboid, columnar nuclear migration, Tome’s
process present for secretion, ruffle -
ended, smooth ended,
tome’s processes contribute to _____ formation
rod
During amelogenesis the outer enamel epithelium, stellate reticulum and stratum
intermedium fuse to form the _________
papillary layer
the papillary layer has _______, as the ameloblast layer is avascular, and supply nutrients to ameloblasts for _______
formation
blood vessels, enamel
as you move toward the crown of the tooth the cells will become more _______
differentiated
during the histodifferentiation phase the nuclei shift toward ________, _______ prominent and in center of cell, abundant ______ formed, junctional complexes form around cell at ________ and a ________ can be seen
stratum intermedium, golgi, RER, both ends, terminal web
during the differentiation stage the ameloblasts with secrete _______ and initially there is a ________ between ameloblasts and odontoblasts
enamel proteins, basal lamina (BL)
in tome’s processes the _______ holds cells tightly together as enamel is made
terminal web
during the initial secretory stage the production of ________ begins, _________ commences and ______ are not yet formed,
just crystals
enamel proteins, mineralization, rods
during the secretory stage extensive ________ is formed and it is surrounded by RER
golgi complex
________ are hydrophobic heterogeneous enamel proteins found on _________, contain seven exons where alternative splicing may play a role
amelogenins, both X and Y
chromosomes
amelogenins regulate growth in crystal
_______ and ______
thickness, width
self-assembly of amelogenin protein into _______ has been recognized as a key factor
in controlling the oriented and elongated growth of ________ during dental enamel biomineralization..
nanospheres, hydroxyapatite crystals
two amelogenins include _______ and _______
TRAP (tyrosine-rich amelogenin polypeptide), LRAP (leucine-rich amelogenin polypeptide)
the nonamelogenins includes ________ which promotes mineralization, ______ which helps with crystal nucleation and growth and _______ that is not specific to enamel and its function is unclear
ameloblastin, enamelin, tuftelin
ameloblastin and amelogenin are found in the same _______
secretory vesicles
Initially when enamel is laid down there is
only the _______ portion of Tome’s process which leads to the formation of initial enamel without clear ______
proximal, rods
the dental enamel junction is the close intermingling of _______ collagen, scaffold for ______, and _____
dentin, mineral, enamel
As ameloblasts move away from dentin the _______ Tomes’ processes form and secrete _______ and the _______ Tome’s process secrete _______
distal, rod enamel, proximal, interrod enamel
the two sites if enamel secretion happens by the cell junctions of tome’s processes where _______ enamel formed and the the tip of Tomes’ process where _____ enamel is formed
interrod, rod
The proximal region of secretory ameloblasts where the _______ enamel forms are areas that have very highly folded _______
interrod, membranes
Structureless/initial enamel forms first at the _________, then the _______ enamel is formed, tome’s process then secretes _______ enamel and each ameloblast gives rise to a rod
dentinoenamel junction, proximal, rod
Secretion of enamel at the proximal site close to junctional process forms _____ into which Tomes’ processes fit.
pits
the pit where the tome’s process fits is then filled in with matrix….pit enamel becomes the enamel ______ and wall enamel becomes the
_______ enamel.
rod, interrod
Enamel in the outer third has a different
_______ due to changes in the morphology of Tomes’ processes and the cells begin to develop ______ borders
orientation, ruffled
Initial and final enamel as well as interrod enamel is similar, produced by ______
surface of Tomes’ process, thus _____ are
sandwiched between two layers of initial
and final enamel
proximal, rods
during the maturation stage, ameloblasts get _______ and ameloblasts then have two morphologies: _______ cell border: adding _______ material and a ______ ended border: removal of ______ and ______
material
shorter, ruffled, inorganic, smooth, water, organic
the transition to ruffled ameloblasts occurs when _______ begins and proceeds for a
prolonged time period
apoptosis
_______ of ameloblasts will die through apoptosis
50%
the maturation phase starts the process of removing ______ and ______ proteins and the enamel crystals get larger
fluids, matrix
During maturation ameloblasts undergo _______ which is the process of ruffled border to smooth border
modulation
ruffled ameloblasts produce _______ ions, _______ the enamel fluid to prevent
reverse demineralization and maintains _____ for degrading matrix
bicarbonate, alkalizes, pH
in smooth ameloblasts molecules withdrawn
from the enamel pass between ameloblasts
and through the lateral borders of the cell and the decreased ________ allow for
fluid and its contents to move between the
cells
tight junctions
In the maturation phase a ________ is formed and the cells are beginning to separate from the ______
basement membrane, enamel
in the “Protective” Stage the basal lamina is _______ and _______ are formed between ameloblasts
secreted, hemidesmosomes
stage 1 of mineralization is the formation of _______ mineralized enamel (30%)
partially
stage 2 of mineralization is the secondary increase in mineralization from ______ to ______ layer (deeper layers more mineralized)
surface, deeper
the 3rd stage of mineralization is from innermost layer outward, the mineralization continues until the surface layer is seen mineralizing _______
more slowly
the 4th stage of mineralization is the heavy mineralization of ______ layer
outer
some organization and features of
enamel include rods run _______ to surface of dentin, they run circumferentially around long axis of tooth but rods are not formed in a ________ and the inner part of enamel the rods ______
perpendicular, straight line, intertwine
the striae of retzius are _________ due to 6-11 day cycles of enamel formation by ameloblasts
incremental lines of growth
the stria of Retzius ends at the surface
are referred to as _______
perikymata
Enamel is laid down at about ______ per day
~4μm
Hunter-Schrager Bands are optical pattern of gray and white areas, resulting from changes in ______ direction
rod
Gnarled enamel is the cuspal region of the
crown where the enamel rods ______ and
become _______
twist, irregular
the dentinoenamel junction is ____ shaped
scalloped
Enamel tufts are abrupt changes in enamel rods at the __________, they are less _______ in this region and have a different ______ of rod to interrod enamel
dentinoenamel junction, mineralization, ratio
Enamel lamellae run from the enamel surface and are filled with enamel ______ or ______
protein, organic debris
Enamel Spindles are ________ processes caught between ________ formed by adjacent
ameloblasts and they are similar to tufts
but much _____
ondontoblast, enamel, shorter
during aging enamel wears, erodes, discolors and has reduced _______
permeability
Excess acid in oral cavity, ______ and excessive acidic drink intake (coke/pepsi
pH 2.5; coffee ~ 4.5 pH) all affect the enamel
bulimia
tetracyclin usage in utero or in infants can cause _______
enamel discoloration
Excess fluoride treatment can also _____
enamel
stain
