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histopath > amelogenesis and enamel > Flashcards

amelogenesis and enamel Flashcards

1
Q

compared to other mineralized tissues, what are extremely large, highly oriented, and packed into ROD LIKE structures?

A

amelogenesis

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2
Q

known as ENAMEL ROD

A

Ca hydroxyapatite crystals

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3
Q

even though enamel rod is 96% mineral, the structure exhibits some

A

flexibility

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4
Q

composition of enamel

A

1% water
3% organic components
96% inorganic

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5
Q

organic component of enamel:

A

tyrosine-ruch amelogenin protein(s) (TRAP)

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6
Q

what constitutes 90% of the protein in enamel?
5%?

A

amelogenin 90
enamelin 5

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7
Q

what is 5x harder than dentin?

A

enamel

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8
Q

enamel is an _____ tissue

A

acellular

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9
Q

formation of enamel involves both _____ and _____ activities of ectodermally derived cells

A

secretory and resorptive

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10
Q

hardest tissue in body?

A

enamel

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11
Q

what does enamel lack in matrix

A

collagen (no collagen in matrix)

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12
Q

what are the 4 TRAP proteins?

A

amelogenin
enamelin
tuftelin
sheathlin

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13
Q

what trap protein is found in enamel tufts at DEJ

A

tuftelin

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14
Q

what is the inorganic component of enamel

A

calcium hydroxyapatite

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15
Q

amelogenin exhibits thixotropic properties which is the ability to:

A

flow under pressure

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16
Q

as the enamel crystal size increases, the amelogenin flows away from between the crystals and back towards the ameloblasts where it is degraded by

A

proteolytic enzymes (serine proteases and enamelysin)

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17
Q

unlike other hard tissue proteins, enamel organic protein is labile (can change) and exhibits both what 2 changes:

A

qualitative and quantitative

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18
Q

what is the largest os the enamel matrix proteins?

A

enamelin

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19
Q

this protein is acidic, phosphorylated, and glycosolated protein

A

enamelin

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20
Q

enamelin is restricted to the

A

enamel rod area

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21
Q

what plays a role in crystal growth and nucleation

A

enamelin

22
Q

what protein is restricted to the DEJ in enamel tufts

A

tuftelin

23
Q

this protein plays a role in induction, the initiation of mineralization, and possibly functions as a junctional protein linking enamel and dentin

A

tuftelin

24
Q

this protein is initially found throughout the rod and interrod enamel, but preferentially in rod sheaths

A

sheathlin

25
Q

RECIPROCAL INDUCTION=

  1. pre-tooth bud stage ectoderm specifies the “dental nature” of the underlying:
  2. neuron crest cells (ectomesenchyme) then induce formation and proliferation of the:
  3. the dental lamina eventually separates into an outer and inner:
A

mesenchyme (neuronal crest cells)

dental lamina

dental epithelium

26
Q

RECPIROCAL INDUCTION=
1. inner enamel epithelium induces differentiation of:

  1. odontoblasts secrete the mantle layer of:
  2. once the mantle layer of dentine is formed, ameloblast differentiation is initiated and this begins shortly after
A

odontoblasts

dentin

amelogenesis

27
Q

the gradient of cellular differentiation, matrix secretion, and mineralization during tooth development is:

A

anterior to posterior (dentition)

and

coronal (crown) to apical (apex) (individual teeth)

28
Q

stages of ameloblast function:

A
  1. morphogenic stage
  2. differentiation stage (tall columnar, induction of odontoblasts)
  3. secretory stage (tome’s processes)
  4. maturation stage (smaller, removing proteins to harden up)
  5. protective stage (squishing together of all lays= reduced enamel epithelium)
29
Q

what is the angle of the enamel rod’s forming face during secretory phase?

A

tome’s process
- angle of forming face/tome’s process will determine what angle enamel rods are produced

30
Q

how many individual ameloblasts contribute to the composition of one enamel rod?

A

4

31
Q

structural feature of enamel.

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

represents 4-8 days of rhythmic enamel matrix

A

striae of retzius

32
Q

structural feature of enamel.

on each rod represent 24 hours of enamel matrix production, about 4/day

A

cross striations

33
Q

external (surface) manifestations of the striae of retzius

A

perikymata

34
Q

an optical phenomenon produced by changes in direction of the enamel rods. seen only in ground histologic sections viewed by reflected light

A

hunter-schreger bands

35
Q

most commonly found in cusp tips. enamel rods appear to be twisted in a complex arrangement.
very resistant to fracture and abrasion

A

gnarled enamel

36
Q

hypomineralized areas of enamel extending from the DEJ for considerable distances into the enamel. May be envolved with smooth surface caries

A

enamel lamellae

37
Q

cracks extend from the enamel surface for variable distances into the enamel. may extend into the dentin

A

enamel crack

38
Q

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

A

enamel tufts

39
Q

represent extensions of odontoblastic processes and tubules across the basal lamina during initial stages of matrix formation

A

enamel spindles

40
Q

this of enamel is primarily related to a delay in the removal of amelogenin during maturation. birthing difficulties and nutritional deficiencies also commonly disturb development

A

hypomineralization

41
Q

this of enamel is generally induced by infectious diseases of childhood (measle, rheumatic fever, mumps) which leave a defect in those parts of the teeth actively developing at the time of the infection

A

hypoplasia

42
Q

this occurs to enamel as a result of a diet containing high levels of fluoride. severe enamel fluorosis may manifest as opaque areas, light-brown mottling, and surface pitting

A

mottle enamel

43
Q

defective enamel matrix deposition which voids the possibility of enamel mineralization.

although there are multiple types of amelogenesis imperfect, the more common types are AUTOSOMAL DOMINANT inherited

A

amelogenesis imperfecta

44
Q

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

most often involve maxillary molars and CEPs most often involve the mandibular molars

A

enamel pearls and cervical enamel projections (CEP)

45
Q

a deep invagination of the crown or root that is lined with enamel
-most commonly involves the maxillary incisor
-prevalence rate of .4% to 10% of all patients

A

dens-in-dente

46
Q

enamel thickness ranges from what measurment over the cusps

A

2-2.5 mm

47
Q

what represents an exaggerated hypomineralized striae of Retzius that forms at birth

A

neonatal line

48
Q

the perikymata (enamel surface manifestations of the striate of retzius) are also known as the

A

imbrication lines of pickerill

49
Q

what is comprised of the remnants of the reduced enamel epithelium (aka primary enamel cuticle or Masmyth’s membrane)

A

enamel cuticle

50
Q

(aka acquired pellicle or salivary pellicle) is comprised of glycoprotein precipitates derived from saliva and/or gingival crevicular fluids

A

enamel pellicle

51
Q
A

histopath (13 decks)

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