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
2
Q
Classifications of cementum: By location
A
- Radicular cementum ⇢ Found on root surface
- Coronal cementum ⇢ Forms on enamel covering crown
3
Q
By cellularity
A
- Cellular ⇢ cementum containing cementocytes within matrix
- Acellular ⇢ Cementum without cells in matrix
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
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
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
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
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
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
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
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