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Histopathology > Amelogenesis And Enamel > Flashcards

Amelogenesis And Enamel Flashcards

1
Q

what are enamel rods

A

large slightly flexible, highly oritented calcium hydrozyapatite crystal

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2
Q

what is enamel composed of

A

-96% inorganic (calcium hydroxyapatite)
-3% organic compounds (TRAP)
-1% water

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3
Q

what constitues 90% of protein in enamel

A

amelogenin

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4
Q

describe amelogenin

A

thixotropic- ability to flow under pressure
-labile and exhibits both quantitative and qualitative changes

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5
Q

describe enamelin

A

phosphorylated-plays a role in crystal growth and nucleation

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6
Q

where is tuftelin located

A

in DEJ in enamel tufts

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7
Q

where is sheathlin found

A

located in rod sheathes

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8
Q

what happens in reciprocal induction

A

-pre-tooth bud stage ectoderm specifies the dental naure of the underlying mesenchyme
-neural crest cells then induce formation and proliferation of the dental lamina
-dental lamina eventually separated into the outer and inner dental epithelium
-inner enamel epithelium induces differentation of odontoblasts
-odontoblasts secrete mantle layer of dentin and ameloblast differentiation is initated and amelogenesis begins

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9
Q

where does amelogenesis occur

A

anterior -> posterior and coronal -> apical

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10
Q

what is the function of the morphogenic stage

A

cuboidal inactive cell

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11
Q

what is the function in the differentation stage

A

-cell increases in size and becomes tall and columnar
- junctional complexes occur
-induction of odontoblasts and mantle dentin

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12
Q

what is the function in the secretory stage

A

tomes processes and secretory granules

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13
Q

what is the function of the maturation stage

A

-height decreases
-ruffled border occurs

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14
Q

what is the function of the protective stage

A

hardening phase
- squishing together of the layers and form reduced enamel epithelium

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15
Q

what are tonofibrils

A

what the terminal web region in fully differentiated ameloblasts comprised

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16
Q

what do horizontal enamel rods represent

A

24 hour period of enamel production

17
Q

how often do tomes processes constrict and change the angle at which the enamel is produced

A

every 4-8 days

18
Q

what is the striae of retizius

A

angled enamel rods
-incremental lines produced by periodic constriction of tomes process associated with corresponding increase in the face forming the interrod enamel

19
Q

how big are enamel rods

A

-takes 4 ameloblasts to contribute to
- about 60 nm in width and 100 microns long

20
Q

what are perikymata

A

external manifestations of the striae of retzius

21
Q

what are hunter schreger bands

A

optical phenomenon produced by changes in direction of the enamel rods

22
Q

what is gnarled enamel and where is it found

A

found in cusp tips
- enamel rods appear to be twisted in a complex arrangement, resistant to fracture and abrasion

23
Q

what is enamel lamellae

A

hypomineralized area of enamel extending from DEJ for considerable distances into the enamel

24
Q

what are enamel tufts

A

hypomineralized areas of enamel at the DEJ that are rich in enamelin and tuftelin

25
Q

what is the enamel spindle

A

represents extensions of odontoblastic processes and tubules across the basal lamina during intitial stages of matrix formation

26
Q

what is hypomineralization caused by

A

delay in the removal of amelogenin during maturation

27
Q

what is hypomineralization characterized by

A

chalky white opaque colaration

28
Q

what is hypoplasia caused by and what is it characterized by

A

-caused by infectious diseases of childhood which leave a defect in those parts of the teeth developing at the time of infection
- characterized by pits and grooves, notches

29
Q

what is fluorosis caused by

A

too high levels of fluoride

30
Q

what happens in amelogenesis imperfecta

A

defective enamel matrix deposition which voids the possibility of enamel mineralization

31
Q

what is the inheritance pattern of amelogenesis imperfecta

A

autosomal dominant

32
Q

what are enamel pearls and cervical enamel projections

A

-defects that occur during apposition and maturation stages of tooth development due to displacement of ameloblasts to root surface

33
Q

where are enamel pearls most often found/ CEP?

A

enamel pearls in max molars
CEP in mand molars

34
Q

what is dens-in-dente

A

invagination of crown or root that is lined with enamel

35
Q

what is neonatal line

A

an exaggerated hypomineralized striae of retzius that forms at birth

36
Q

what is imbrication lines of pickerill

A

the enamel surface manifestations of the striae of retzius

37
Q

what is the enamel cuticle made of

A

primary enamel cuticle comprised of the remanence of the reduced enamel epithelium

38
Q

what is the enamel pellicle

A

the acquired pellicle comprised of glycoprotein precipitates derived from salivary and gingival crevicular fluids

39
Q

what is another name for enamel cuticel

A

Nasmyth’s membrane

Histopathology (14 decks)

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