Cementum

Question 1

What is the percentage of organic and mineral components of cementum?

Answer 1

50-50

Question 2

What are the organic components of cementum?

Answer 2

-type I collagen
-proteoglycans
-glycosaminoglycans
-phosphoproteins

Question 3

What are the functions of cementum?

Answer 3

-provide attachment for PDL
-provide limited compensation for occlusal wear through continuous apical apposition
-may participate in repair of root fracture

Question 4

What is the origin of cementum?

Answer 4

neural crest cells

Question 4

Is cementum vascular?

Answer 4

nope

Question 5

Where is cementum the thinnest?

Answer 5

at the CEJ
-increases in thickness as it goes down the root
(90-150 microns at mid root )
(150-300 microns at the apex)

Question 6

What are cementoblasts?

Answer 6

cells responsible for secreting the organic matrix of cementum

Question 7

What zone of dental follicle do cementoblasts come form?

Answer 7

inner

Question 8

When does differentiation of cementoblasts start?

Answer 8

when there is disruption in hertwigs root sheath
-allow the cells to make contact with the dentin
-dentin matrix growth factors induce the differentation (BMP, FGF, DMP)

Question 9

How do all the mesenchymal cells become cementoblasts?

Answer 9

the growth factors leak out of the pores and activate the cells into the cementoblasts

Question 10

What are depositional and reversal lines?

Answer 10

growth lines in cementum
-indicate incremental growth
-run longitudinally within the cementum

Question 11

What are cementocytes?

Answer 11

cementoblasts that have been mineralized

Question 12

What are lacunae?

Answer 12

space occupied by acell

Question 13

What are canaliculi?

Answer 13

space occupied by cytoplasmic projections

Question 14

What are sharpey’s fibers?

Answer 14

extensions of PDL into the cementum

Question 15

Is cementum poruous?

Answer 15

yes very

Question 16

What is the most common type of CEJ?

Answer 16

overlaping
-there is some overlap between the cementum and enamel

Question 17

Is there is a gap between the cementum and dentin waht can happen? q

Answer 17

the dentin is exposed
-this can cause sensitivty to the tooth

Question 18

What is abfraction?:

Answer 18

loss of tooth surface at cervical areas of teeth causes by tensile or compressive forces during tooth flexure
deep & narrow
non-carious

Question 19

Is abfraction carious?

Answer 19

no

Question 20

What are the charactertistics of abfraction?

Answer 20

deep
V shaped
narrow

Question 21

What is abrasion?

Answer 21

loss of dental tissue by foreign object (brushing teeth too hard)
wide & shallow

Question 22

What are characteristics of abrasion?

Answer 22

located at cervical areas
-wide and diffuse
-canines and premolars most commonly affected

Question 23

What are cementicles?

Answer 23

calcified bodies on or in the cementum and in the PDL
-can be free, attached, or embedded

Question 24

What causes the formation of cementicles?

Answer 24

local trauma or hyperactive occlusion and increase with age

Question 25

What are cemental spurs?

Answer 25

projections fo the cementum into PDL in response to trauma -makes it hard to extract the tooth

Question 26

Is it okay if cementum is exposed to the oral cavity?

Answer 26

no not really

Question 27

What happens to exposed cementum?

Answer 27

becomes hypermineralized which prevents the reattachment of collagen and PDL -will also allow for build up of plaque and calculus -facilitates endotoxin absorption -becomes less porous

Question 28

What is a treatment for exposed cementum?

Answer 28

scaling and root planing -will remove the built up plaque and calculus -can also remove the top layer and may allow for new tissue to grow in

Question 29

What is hypercementosis?

Answer 29

excess production of cellular cementum that generally involves the apical 1/3 of the root

Question 30

What causes hypercementosis?

Answer 30

trauma from occlusion, periapical inflammation, or compensation for occlusal attrition

Question 31

What are accessory canals in the cementum>

Answer 31

lateral canals that allow for vasculature to supply the entire tooth -the number of canals increase as you move toward the apex of the root