15 - Morphology of dental cementum Flashcards

1
Q

Cementum

A

Hard avascular CT that covers roots of tooth

CEJ ⇢ located at cervical margin

  • 30% edge - edge
  • 60% cementum overlaps enamel
  • 10% gap between enamel + teeth
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2
Q

Classifications of cementum: By location

A
  • Radicular cementum ⇢ Found on root surface
  • Coronal cementum ⇢ Forms on enamel covering crown
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3
Q

By cellularity

A
  • Cellular ⇢ cementum containing cementocytes within matrix
  • Acellular ⇢ Cementum without cells in matrix
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4
Q

By presence of collagen fibrils in matrix

A
  • Fibrillar ⇢ cementum w/2 matrix that contains well defines collagen I fibres
  • Afribrillar ⇢ Matrix without collagen fibrils but has granular consistency
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5
Q

By origin of matrix fibres

A
  • Extrinsic (role in tooth anchorage) ⇢ Cementum that contains extrinsic fibres ⇢ Sharpey’s fibres
  • Intrinsic ⇢ Cementum that contains mainly intrinsic fibres ⇢ Cementocytes
  • Mixed
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6
Q

Cementum varieties - Acellular Afibrillar cementum

A
  • Mostly mineralised matrix
  • No fibrils + No cementocytes
  • Produced by cementoblasts
  • Typically found as Coronal epithelium - close to DEJ
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7
Q

Acellular extrinsic fibre cementum

A
  • Matrix has well defined collagen I fibrils
  • Contains Sharpey’s fibres
  • Located at cervical ⅔ of root
  • anchors tooth to periodontal ligament
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8
Q

Cellular intrinsic fibre cementum

A
  • contains cementocytes in a matrix of almost only intrinsic fibres
  • Located at sites of cementum repair
  • Plays no role in tooth anchorage
  • Deposited once tooth is in occlusion:
  • As deposition progresses ⇢ cementoBLASTS trapped in matrix that they secrete ⇢ become cementoCYTES
  • They have processes that lodge in canaliculi ⇢ never extend all the way to the surface
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9
Q

Cellular mixed fibres cementum

A
  • Found on apical ⅓ of root
  • Formation of cementum more rapid here
  • Sharpey’s fibres run more irregularly + more distinguishable than in AEFC
  • Cementoblasts are trapped in lacunae ⇢ become cementocytes here
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10
Q

Intermediate cementum

A
  • thin + amorphous non-cellular layer of hard tissue
  • Deposited by follicular cells of root sheath
  • After deposition ⇢ follicular cells disintegrate + migrate into periodontal tissue
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10
Q

Intermediate cementum

A
  • thin + amorphous non-cellular layer of hard tissue
  • Deposited by follicular cells of root sheath
  • After deposition ⇢ follicular cells disintegrate + migrate into periodontal tissue
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