amelogenesis Flashcards

1
Q

describe enamel

A
  • mineralised epithelial product
  • 96% mineral - hydroxyapatite
  • 1-2% organic matrix
  • enamel proteins
  • NOT collagen etc
  • 2% water
  • starts to form after dentine mineralises
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2
Q

describe enamel spindle formation

A

nucleus of ameloblast polarises, goes to one size odontoblast process may enter enamel epithelium

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3
Q

describe enamel prisms

A

enamel prism shape governed:
- by the tomes process
- direction of migration of the ameloblast
regions formed without a tomes process are aprismatic:
- 1st formed (i.e. innermost) 5micrometres
- last formed (i.e. outmost) 30micrometres

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4
Q

what is the final cue for onset for amelogenesis?

A
  • dentine formation
  • breakdown of basal lamina
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5
Q

Ameloblast

A
  • secretes organic matrix
  • immediate partial mineralisation
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6
Q

amelogenesis maturation by?

A
  • influx of mineral ions
  • breakdown and removal of most of the organic matrix
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7
Q

describe enamel matrix (an epithelial product)

A

organic matrix: amorphous gel
enamel proteins:
- amelogenins (90%)
- enamelins - (~2%) strongly binds to mineral
- tuftelin - confined to ADJ
- enzymes

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8
Q

describe amelogenins

A
  • Rich in proline and glutamine
  • similar in different species - clinically useful
  • hydrophobic - aggregate
  • spread throughout the developing enamel thickness
  • thixotropic
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9
Q

what is the role of enamel proteins?

A
  • aid nucleation of hydroxyapatite
    epitactic matrix
  • orientate + stabilise crystal growth
  • broken down and lost during maturation
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10
Q

what is enamelins?

A
  • the matrix that flows out - amelogenins
  • the matrix that remains - enamelin
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11
Q

describe enamel cuticle

A
  • formed when maturation is complete
  • final ameloblast secretion - the enamel cuticle
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12
Q

describe reduced enamel epithelium

A
  • forms when enamel formation is complete
    derived from:
  • reduced ameloblasts
  • other remmants of the enamel organ OEE etc
  • attached to the cuticle
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13
Q

what is the function of the reduced enamel epithelium ?

A

1) protection of enamel surface from:
- resorption
- prevention of cementum formation
2) provide an epithelial lined pathway for eruption
3) forms initial junction epithelium

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14
Q
A
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15
Q
A
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