Enamel I & II Flashcards
responsible for origin of enamel and has ectodermal origin
enamel organ
Tooth bud undergoes _______ to establish enamel organ in the cap stage
morphogenesis
1st place of mineralization is in the
cusps
we determine shape of the crown in what stage
bell stage
thickening in SR can produce an
enamel cord
enamel formation is induced by onset of
dentinogenesis
simultaneous deposition of enamel/dentin is the ______ stage
appositional
in a mature state, enamel is ____ mineral in the form of hydroxyapatite crystals
96%
enamel does not have ____ or _____
collagen or keratin
only called an ameloblast if it’s secreting
enamel
what are the stages of the life cycle of an ameloblast
- Morphogenetic
- Organizing - histodifferentiation
- initial secretion (no Tp)
- secretory (Tp)
5-6. maturative - protective
what are the % of the ruffle border and smooth border
80% ruffle border
20% smooth border
You lose _____% of cells between the secretory and maturative stage
25%
the _____ border increases the mineralized component of the enamel
ruffle
if cells are cuboidal in the SR, what does that mean and what stage is that?
cuboidal stage means nothing is happening so this is the morphogenetic (resting) stage
IEE cells are not cuboidal and they’re ______
polarized
in the late organizing stage, the cells are
large & polarized
what is happening to basal laminate in the late organizing stage? what about to the cells of the ODP?
the BL is kind of breaking down
the cells of the ODP are beginning to differentiate and clump together
junctional complexes are present at _____ and _____ locations
distal & proximal
ameloblasts are distinguished by a
Tome’s process
proximal Tome’s process has what kind of enamel
interrod
distal Tome’s process has what kind of enamel
rod enamel
no Tome’s process has what kind of enamel
rodless enamel
Tome’s process is responsible for the structure of
enamel
interrod enamel is produced in the ____ of the keyhole
tail
rod enamel is produced in the ____ of the keyhole
body
secretory granules are released from Tome’s process which contain the following organic compounds
Amelogenins (90%)
Ameloblastin
Enamelin (10%)
immature enamel has a much higher ____ content
organic
can you follow rod enamel all the way to the DEJ? why or why not?
No, because rodless enamel is at the DEJ
at the end of the secretory stage, there is a portion of what kind of enamel
rodless
when ameloblasts are about to stop, there is no more
Tome’s process
When the thickness of enamel is achieved, the ameloblasts enter the ______ stage
maturation
in the maturation stage there is modulation between the
ruffle and smooth borders
the ruffle border adds ____ and deposits into the
Ca2+ ion ; enamel
the proximal area of the ruffle border is ____ for _____
open ; influx
the smooth border adds
proteinases to break down the organic component and pinocytosis of fluids
the distal area in the smooth border are ____ for _____
open ; pinocytosis of proteins to break down
maturation means
more mineralized
in maturation, how do we become more mineralized?
by secreting more crystals or making them larger
immature enamel = no more _____ so you can’t secrete more _____ aka why you can’t fix _____
Tome’s process ; crystals ; enamel
Fully mature enamel is ___ mineral
96%
the final stage (protective stage) is the
REE
the final stage (protective stage) is when the REE separates the enamel from the tissues in the ____
pulp
REE also plays a role in breaking down the ___ and ___ , helping the _____ of the teeth
bone and tissues ; eruption
REE produces odontoclasts which breaks down
dental bone and roots
What happens to REE? Nasymth’s Membrane
it merges with the oral epithelium
it comes out with the teeth
Enamel is secreted by
Tome’s process
there is no more secretion of ameloblasts in the ____ stage so no more ____ secretion is possible
REE ; enamel
rods run an irregular course from ____ to ____
DEJ to surface
The ____ defines the convex, outer surface of the organ
OEE
The _____ lines the concave, inner surface of the organ. Its
cuboidal cells will differentiate into ______
IEE ; ameloblasts
High levels of _______ are present in the SI adjoining the ameloblasts
alkaline phosphatase
Enamel formation is induced by the onset of
dentinogenesis
_____ is the hardest tissue of the body
Enamel
The hardness of enamel makes it a _____ substance
brittle
In the secretory stage, as migration occurs, a conical process, known as ___________, forms at the _______ end
Tome’s process ; distal
amelogensis proceeds at the rate of ___ micrometers per day
4
Once the full thickness of enamel is achieved, the ameloblasts enter the ________ stage
maturation
Histodifferentiation of ameloblasts is
graded
Enamel _________ form the bulk of enamel
rods (prisms)
matrix constituting the interrod region is formed in association with the base, or _____ end of Tome’s process
proximal
_______ are a series of dark bands seen in both cross sections and longitudinal sections of a ground tooth
Lines of Retzius
____________ are seen as alternating dark and light bands extending from the DEJ to the enamel surface in longitudinal ground sections which are produced by changes in __________
Bands of Hunter-Schreger ; rod direction
_________ appear as linear cracks, or defects, extending through the thickness of enamel
Enamel lamellae
________ appear as tufts of grass extending from the DEJ part way into enamel
Enamel tufts
__________ are seen as stubby, dark-appearing projections at the DEJ.
They result from the cytoplasmic processes of
odontoblasts which penetrate the IEE as dentinogenesis begins
Enamel spindles
________ are furrows on the surface of enamel. They are regarded as the surface manifestations of the
lines of ____
Perikymata ; Retzius
Differing path of enamel rods,
with intertwining, is prominent in inner 2/3’s of enamel
Hunter-Schreger Bands
Rods are arranged ________ in horizontal planes, becoming more vertically inclined toward _____
radially ; cusps
The first and last
formed enamel is _____
_______ is not present
Rodless ; Tome’s process
_________ are seen as dark lines from DEJ to surface, reflecting incremental synthesis of enamel
Lines (Striae) of Retzius
______ reflects change of physiology on enamel formation as a consequence of birth
Neonatal line
Tufts are locations of
_________ showing a twisting course
hypomineralized rods
Spindles reflect an overgrowth of ______ processes at the start of ______
odontoblast ; apposition
Mottling of teeth
too much fluoride in a natural source of water while teeth were developing
dental fluorosis
fluoride binds to ______
making them more ______ to
acid demineralization
hydroxyapatite crystals ; resistant
Fluoride in a carious lesion,
promotes _______ of enamel
remineralization
Fluoride in plaque, produces a ______ in the activity of bacterial enzymes that synthesize ____
reduction ; acid
wear on occluding surfaces,
abrasives in tooth paste
Abrasion/Attrition
loss by chemical exposure (not from bacteria)
ex: stomach acid
erosion
loss by exposure to organic acids from cariogenic bacteria
caries
Formation of a carious lesion is a dynamic process with
stages of ____________,
without cavitation (initially).
______ and ______ ions
from saliva maintain a surface covering. Overtime,
demineralization will prevail, creating a cavity
demineralization/remineralization ; Calcium and phosphate ions
