histo - enamel2014
TRANSCRIPT
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DR. SAMIHA J. SAMAR
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- Substantia adamantia
- Ectodermal derivative- Covers the entire
anatomical crown oftooth
- Provides contour andshape to the crown
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- Hardest tissue in thebody
- Brittle- Acellular
- Permeable
- Thickness (!microns"#$% mm&
- Color (yellowish
white"'rayish white&
- translucent
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- )* inor'anic material (hydro+yapatite)
trace minerals (strontium,magnesium, lead, fuoride)
- ,* or'anic material
water
amelogeninsenamelins
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$Enamel rods
#$-od sheath
.$/nterrodsubstance
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• Ma !ar "rom #-$%min num&er
• Has t'ree arts thebody or head0 theneck and the tail
• *ollows wavy course "rom D+J to sur"ace o"enamel
• In cross section maaear as 1sh scale,paddle shaped orma 'a!e a keyhole
pattern
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section# teeth teeth
/ncisal2occlusal !erticalo&liue same
3iddle 'oriontal same
Cervical aical 'oriontal
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- Boundary ofenamel rodand interrod
substance- 4ess calci1ed
area
- Cements or holds
to'ether the enamel rods
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- /ntertwinin' ortwistin' o"
enamel rods atincisal or cuspalre'ion
- Aids in resisting
'ig' masticatorloads wit'out"racture
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- Series o" alternatin'dark and li'htbands in t'e enamel
- Due to chan'e indirection o" t'eenamel rods
- Dar/ &ands 0
dia5ones- 1ig't &ands 0
para5ones
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- Brownish bands t'at
illustrate t'eincremental pattern o"laing down o" enamel
- 2omara&le to 'rowth
rin's o" t'e tree
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- 1ine o" boundary o" renatal andostnatal enamel(in deciduous
teet' onl)- Accentuated
incrementallines of -et5ius
- 3rominent incer!ical areas
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- 4'in, lea6ikestructures t'at
e5tends "rom enamelsur"ace towards D+Jand e!en towardsdentin
- 7r'anic in nature andhypominerali5ed
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- Aear as tufts of'rass t'at ro6ect into
t'e enamel- 7arrow ribbonlike
structure
- Hypocalci1ed enamel
rods andinterrismaticsu&stances t'atoriginates "rom D+J to
at least $8 o" t'eenamel
- 4ess minerali5ed0 wea/ened lanes
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- 89 microns t'ic/
- 3resent in all $ teet'
and :9 ; o" % teet'- 8o prism outlines
- More heavilyminerali5ed area t'an
underling enamel
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- E+ternalmanifestation o"incremental lines
o" Retius-
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- 2onca!e and !arin det' and s'ae
- Ma contri&ute toad'erence o"laue material
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- 7arrow 1ssurelikestructures w'ic' areactuall outer ed'es ofthe enamel lamellae
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- Primary enamelcuticle
- 8asmyth9smembrane
- Delicate mem&ranet'at covers theentire crown of
newly eruptedtooth
- Deri!ed "rom t'eamelo&lasts
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- 3embranapreformativa
- :unction between
dentin andenamel
- Scalloped or has apitted aearance
- Hypominerali5ed5one
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- 4'ic/ened end o"odontoblastic process t'at crosses t'e D+J and
is entraed in t'eenamel
- Pain receptors
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- a$k$a$ Enameldroplets
- HE-S t'at &ecomesdetac'ed and
di=erentiate intoameloblasts and"orms enamel in t'e&i"urcation or
tri"urcation o" teet'
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$. +namel is incapable o" reairand relacement.
%. +namel undergoes attrition0abrasion and erosion$
8. As t'e toot' ages t'ere is loss ofrod ends and 6attenin' ofperikymata.
>. +namel &ecomes darker in color.#. +namel &ecomes lesspermeable wit' ad!ancing age.
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$ The course or direction of enamelrods is an important consideration
in cavity preparation.
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#$ Enamel isbrittle and
must besupported bysound dentin$
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.$ Presence ofdeep pits and
1ssurespredispose teethto dental caries$
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,$ ;ental lamellaeand enamel tufts
are predisposin'location fordental caries$
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%$ Enamel is permeable to6uoride and other substances$
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6. Keep the cervical surface ofenamel well polished and smooth.
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