Cementum

Question 1

Substance: Dentin
Organic:
Mineral:

Answer 1

30%

65-70%

Question 2

Substance: Bone
Organic:
Mineral:

Answer 2

30-35%

60-65%

Question 3

Substance: Cementum
Organic:
Mineral:

Answer 3

50-55%

45-50%

Question 4

Organic components include: (4)

Answer 4

• Type I collagen (intrinsic and Sharpey’s fibers)
• Proteoglycans
• Glycosaminoglycans
• Phosphoproteins

Question 5

Cementum provides

Answer 5

attachment for the PDL

Question 6

Cementum may provide limited compensation for

Answer 6

occlusal wear through continuous apical apposition

Question 7

Cementum made participate in

Answer 7

rapir of root fracture

Question 8

Cementum is — in origin.

Answer 8

ectomesenchymal

Question 9

Cementum contains less mineral than both

Answer 9

bone and dentin.

Question 10

Unlike bone, cementum is

Answer 10

avascular, not
innervated, and contains no Haversian or
Volkmann’s canals.

Question 11

Cementum is thinnest at the

Answer 11

CEJ (30-50 μm)
and progressively increases in thickness to 90-
150 μm at mid-root to 150-300 μm at the apex

Question 12

CEJ

Answer 12

30-50 um

Question 13

mid root

Answer 13

90-150 um

Question 14

apical 1/3

Answer 14

150-300 um

Question 15

Cementoblasts, the cells responsible for secretion of the

organic matrix of cementum, are derived from

Answer 15

undifferentiated
mesenchymal cells that originate in the proximal (inner) zone
of the dental follicle. In turn, all cells in the dental follicle are
derived from ectomesenchyme (neural crest cells).

Question 16

Differentiation is initiated with

Answer 16

disruption of Hertwig’s
epithelial root sheath, allowing the undifferentiated
mesenchymal cells to make contact with the adjacent dentin.
Dentin matrix growth factors (e.g., BMP, FGF, DMP) then
induce the differentiation process.

Question 17

Cementum (Histologic Features) (5)

Answer 17

 Depositional lines 
 Reversal lines 
 Cementoblasts 
 Cementocytes 
 Sharpey’s fibers (PDL)

Question 18

 Cementocytes (2)

Answer 18

• Lacunae

* Canaliculi

Question 19

Depositional lines
Reversal lines
Both indicate

Answer 19

incremental
growth, and run longitudinally
within the cementum

Question 20

Lacunae

Answer 20

(space
occupied by
cell)

Question 21

Canaliculi

Answer 21

(space occupied
by cytoplasmic
projections)

Question 22

CEJ
Overlap
End-to-End
Gap

Answer 22

60%
30%
10%

Question 23

Abfraction

Answer 23

Loss of tooth surface at the cervical areas of teeth caused by
tensile and compressive forces during tooth flexure
Affects buccal/labial cervical areas of teeth
Deep, narrow V-shaped notch
Commonly affects single teeth with excursive interferences or
eccentric occlusal loads

Question 24

Abrasion

Answer 24

Loss by wear of dental tissue caused by abrasion
by foreign substance (e.g. toothbrush)
Usually located at cervical areas of teeth
Lesions are more wide than deep
Premolars and cuspids are commonly affected

Question 25

Cementicle:

Answer 25

Calcified bodies appearing on or in the cementum and in the PDL. Classified as free, attached or embedded. Cementicles are a response to local trauma or hyperactive occlusion and appear in increasing numbers with increasing age.

Question 26

Exposed cementum is hypermineralized which prevents

Answer 26

reattachment of | collagen.

Question 27

Exposed cementum facilitates | attachment of

Answer 27

plaque and | calculus

Question 28

Exposed cementum facilitates

Answer 28

endotoxin absorption

Question 29

Hypercementosis:

Answer 29

The excessive production of cellular cementum that generally involves the apical 1/3 of the root. Etiology is variable involving such factors as trauma from occlusion, periapical inflammation, or compensation for occlusal attrition.