cementum

Question 1

composition

Answer 1

50-55 mineral

50-45 organic

Question 2

organic contents of cementum

Answer 2

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

Question 3

functions cementum

Answer 3

 Provides attachment for the PDL
 May provide limited compensation for occlusal wear through continuous apical apposition
 May participate in repair of root fracture

Question 4

general characteristics of cementum
origin?
mineral content?
vascular? 
thinnest and thickest where?

Answer 4

 Cementum is ectomesenchymal in origin.
 Cementum contains less mineral than both
bone and dentin.
 Unlike bone, cementum is avascular, not
innervated, and contains no Haversian or
Volkmann’s canals.
 Cementum is thinnest at the CEJ (30-50 μm)
and progressively increases in thickness to 90-
150 μm at mid-root to 150-300 μm at the apex.

Question 5

cementum thickness

where is it more cellular?

Answer 5

CEJ Mid-root
30-50 m 90-150 m

Apical 1/3/ Apex
150-300 m

more cellular towards the apex

Question 6

cementum embryogenesis

how its initiated

Answer 6

Cementoblasts, the cells responsible for secretion of the
organic matrix of cementum, are derived from 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).

Differentiation is initiated with pores 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 7

histologic features of cementum

Answer 7

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

Question 8

Depositional lines

Reversal lines

Answer 8

Both indicate incremental growth (collagen laid down then mineralized)
run longitudinally within the cementum from crown to root

Question 9

Cementocytes

Answer 9

cell secrete then mineralize the matrix, trapping themselves
• Lacunae (space occupied by cell)
• Canaliculi (space occupied by cytoplasmic projections

Question 10

Sharpey’s fibers (PDL) of cementum

Answer 10

cementum is porous allowing for PDL insertion via sharpey’s fiber
PDL fibers passing into acellular cementum

Question 11

CEJ variations

Answer 11

60%- overlap of cementum over the enamel
30%- end to end meeting of the enamel to the cementum
10%- gap between the enamel and cementum=causes dentinal sensitivity with exposed dentin

Question 12

abfraction

Answer 12

non-carious
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 13

abrasion

commonly affected teeth?

Answer 13

non-carious
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 14

cementicle

respone to?

Answer 14

Calcified bodies appearing on or in the cementum and in the PDL.

Classified as free, attached or embedded.

free: in PDL
attached: to the cementum
embedded: within the cementum

Cementicles are a response to local trauma or hyperactive occlusion and appear in increasing numbers with increasing age.

Question 15

cementum spurs

forms in response to?

Answer 15

response to trauma
stick off of the cementum, projecting outwards
can lead to complications with extractions

Question 16

cementum in perio disease

Answer 16

 Exposed cementum is hypermineralized which prevents reattachment of collagen.
cementum exposed to the oral cavity will become hyper mineralized to compensate for the hostile environment

 Exposed cementum facilitates attachment of plaque and calculus
although hypermineralized, it is still a bumpy porus surface which facilitates this attachment

 Exposed cementum facilitates endotoxin absorption

Question 17

SRP

Answer 17

done in cases of exposed cementum that has allowed plaque and biofilm to accumulate, endotoxin absorption occurring as well
Will remove all plaque and biofilm as well as any endotoxin absorbed cementum

Question 18

hypercementosis

due to?

Answer 18

due to trauma, occlusion (wear), or inflammation

results in excess cementum forming at the apical thrid of the root, can have a bulbous root appearance

Question 19

root resorption

Answer 19

root can be resorbed for may reasons, mostly unknown but accelerated ortho is one

Question 20

root repair to fracture

Answer 20

can occur due to the accessory/lateral canals
these channels allow vasculature to reach the avascular tissue (cementum) and bring nutrients and GF from the interstitial spaces for repair
in single-rooted teeth these channels are most abundant in the apical third=most successful repair occurs here
in multirooted teeth most accessory canals are located at the level of the furcation=best site of repair