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cell metabolism > Enamel > Flashcards

Enamel Flashcards

1
Q

Enamel Composition

A

96% hydroxyapatite (crystaline calcium phosphate) 4% organic and water

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2
Q

Enamel Rods

A

Tightly packed hydroxyapatite Perpendicular to DEJ

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3
Q

Enamel Rod Characteristics

A

Look like keyholes Crystals in head align with long axis of rod Tail crystals are oriented cross axis

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4
Q

Lines of Retzius ( Enamel Striae)

A

Point Incisally from the DEJ

In transverse sections are concentric rings (like tree rings)

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5
Q

Neonatal Line

A

Found in all primary teeth

some permanent cusps of 1st molars

Represents physiological change on ameloblasts

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6
Q

Perikymata

A

Shallow grooves where lines of Retzius terminate

Usually wear

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7
Q

Hunter-Schreger Bands

A

Alternating dark and light lines due to enamel rod direction change

Mostly found in inner 2/3 of tooth

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8
Q

Enamel Tufts

A

Groups of hypomineralized enamel rods

Short, dark projections near DEJ

No know clinical significance

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9
Q

Enamel Lamellae

A

Cracks on enamel that exted from DEJ to surface

Hypocalcified enamel

May be filled with organic material

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10
Q

Enamel Spindle

A

Odontoblastic process remnants that are trapped during differentiation of ameloblasts

Extensions of dentin tubules

More pronounced beneath cusps or incisal edges (occlusal stress)

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11
Q

Aprismatic Enamel

A

Thin outer layer on newly erupted teeth

Prismless (no emale rods)

Enamel crystals are aligned perpendicular to surface

More mineralized

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12
Q

Gnarled Enamel

A

Over cusps of teeth

Rods are twisted and intertwined

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13
Q

Amelogenesis Beginning

A

Begins at early bell stage

Ameloblasts lay down enamel starting at the crown and working down the CEJ

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14
Q

Ameloblats change shape according to role

A

Secretory Ameloblasts–> Tall columnar

Pre-secretory Ameloblasts–> Short

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15
Q

Goals

Life cycle of Ameloblast

A

Morphogenetic stage (Baby!)

  • Just differentiated from an Inner Enamel epithelial cell to a ameloblast

Histodifferentiation

  • Organelles increase in #number and size

Ameloblast purpose in life is to secrete vesicle containing enamel matrix

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16
Q

The playes in Ameloblasts

A

Mitochondria, nucleus, Golgi, Vesicles, desmosomes

17
Q

Secretory Phase of Ameloblast

A

Ameloblast has a Tomes process to secrete enamel vessicles

  • Proximal portion —> Interod enamel- formed 1st
  • Distal portion—> Rod Enamel

Tomes process is like a frosting tip

18
Q

Composition of initial secretion from ameloblast

A

Initial deposit

  • Makes up 25% of total enamel mineral

Remaining 70% of mineral

  • Result of crystals growing

Last 4-5%

  • Organic and water

Enamel Matrix mineralizes soon after deposition

Deposition and mineralization occur at cusp tip first

19
Q

Ameloblast Maturative Stage

A

Enamel Mineralization increases

  • 30%–>96%
  • Crystals grow wide and long
  • Protein and H2O content lowers

Ameloblast Modulates between

  • Smooth ended ameloblast
  • Ruffled ended ameloblast
  • They work together to INC mineral content
  • Joined by tight junction
20
Q

Ruffle Ended Ameloblast

A

Transport into enamel matrix

  • Calcium
  • Phosphate
  • Bicarbonate ions
21
Q

Smooth Ended Ameloblast

A

Remove things from enamel matrix

  • Enamel matrix proteins
  • Water
22
Q

Enamel Proteins

A

Amelogenin

  • 90% of enam prot, main protein
  • Organizes rods
  • Expression stops once full thickness achieved

Enamelin

  • New crystal formation
  • Elongates crystals

Ameloblastin

  • Adheres ameloblasts to new enamel
  • Found in new enamel
23
Q

Ameloblast Protective Stage

A

After they finish mineralizing they secrete an organic layer called:

Primary cuticle or developmental cuticle

Ameloblasts attach themselves to is by desmosomes

They become short like old grandmas

24
Q

Reduced Enamel Epithelium

A

Covers the tooth when it erupts

Made up of

  • Ameloblasts
  • Papillary layer
    • Fusion of: stratum intermedium, stellate reticulum, outer enamel epi
25
Q

Amelogenesis Imperfecta

A

Group of conditions

Genes for enamel matrix proteins have defects

16+ types

cell metabolism (16 decks)

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