Enamel Flashcards by ava mondschein

Enamel the specialized covering over teeth
developed from _______

epithelium

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Cells that produce enamel, ________, are removed during tooth eruption

ameloblasts

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enamel is translucent, has a light yellow to grey-white color and is very thin about _______

2.5 mm

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enamel is highly mineralized with about ______ mineral, ______ water, and ______ organic material

96%, 3%, 1%

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enamel is hard and brittle where ______ is a necessary base or else enamel can fracture

dentin

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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

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The basic unit of enamel is the ________ and surrounding the _____ is the ________

enamel rod, rod, inter-rod region

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Enamel and rods contain long crystals of about ______ wide and _______ long

60 – 70 nm, >100 μm

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Hydroxyapatite crystals run in ________ in rod and interrod

different directions

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Crystals thicken as enamel matures with increasing ______ content

mineral

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As enamel grows the crystals become
_______, which is based on the _______ structure

hexagonal, calcium phosphate

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ions can be incorporated into the extracellular matrix of the enamel crystals and these ions include ______, _______, ______, and _______

fluoride, magnesium, strontium, lead

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____ can dissolve crystals

acid

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the region between the interrod region and
the rod is the _________ where more organic
material is found

rod sheath

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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

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amelogenesis is the formation of ______

enamel

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the 3 major phases of amelogenesis include the ______, ______ and ______ phases

presecretory, secretory, maturation

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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,

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in the secretory phase ameloblasts make and organize ______

enamel

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in the maturation phase the organic material is _______ and ions are transported for ______ deposition

removed, mineral

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during the secretory stage there is around _______ mineralized enamel, _____ water and _____ protein

29% , 5%, 66%

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during maturation phase there is between ______ mineralized enamel, _____ water and around _____ protein

93-95%, 1-3%, 4%

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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

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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,

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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