(6) Cementum

Question 1

Is precemnetum calcified or uncalcified?

Answer 1

Uncalcified

Question 2

Is cementum more or less hard than dentin and enamel?

Answer 2

Softer than

Question 3

Is cementum more permeable than dentin?

Answer 3

Yes

More permeable

Question 4

What percent of cementum is organic, inorganic and water?

Answer 4

Inorganic - 65%
Organic - 23%
Water - 12%

Question 5

What is the structure of hydroxyapatite in cementum?

Answer 5

Thin plate like apatite crystals

Question 6

What are the non-collage ours components of cementum, which are similar to bone?

Answer 6

Sialoprotein and osteopntin

Question 7

What are the 2 types of cementum?

Answer 7

Cellular and cellular

Question 8

What are the 3 types of cementum fibres based of their origin?

Answer 8

Extrinsic fibre cementum
Intrinsic fibre cementum
Mixed fibre cementum

Question 9

What is extrinsic fibre cementum?

Answer 9

Only has fibres form outside cementum

Sharpeys fibres from outside the cementum

Question 10

What is intrinsic cementum?

Answer 10

No periodontal ligament fibres inserted into it

Question 11

What is the common type of cementum fibre?

Answer 11

Mixed fibre cementum

Question 12

What is mixed fibre cementum?

Answer 12

Collagen fibres that are deposited by cementoblasts (intrinsic fibres)

Extrinsic fibres form the periodontal ligament

Question 13

What produces intricacies fibres?

Answer 13

Collagen from cementoblasts

Question 14

How would you classify cementum which has fibres from the periodontal ligament and has no cells present?

Answer 14

Acellular extrinsic cementum

Question 15

How would you classify cementum which has cells present and fibres from the cementoblasts?

Answer 15

Cellular intrinsic cementum

Question 16

What are the 2 categories to classify cementum?

Answer 16

1. Acellular/ cellular
2. Intrinsic fibres/ extrinsic fibres/ mixed fibres

Question 17

Can you get afibrillar cementum?

Answer 17

Yes

Very rare

Question 18

Where is cementum mainly located?

Answer 18

In the picas area and inter-redicular areas overlying acellular cementum

Question 19

Where is acellular cementum normallly found?

Answer 19

Cervically

Question 20

What is primary cementum?

Answer 20

Acellular

Question 21

What is secondary cementum?

Answer 21

Cellular

Question 22

Answer 22

A = ACELLULAR
B = cellular
C = cementocyte in howships lacunae
D = cementoblasts
E = pre-cementum
F = cementoblasts lining pre-cementum
G = periodontal ligament

Question 23

What is the dark layer between the cellular and acellular cementum?

Answer 23

Afibrillar cementum

Question 24

What is the hyaline layer

Answer 24

hyaline layer of Hopewell-Smith is the most peripheral layer of initially unmineralized dentin that forms immediately subjacent to the cementodentinal junction (CDJ).

Question 25

What direcention do the canaliculi orientate?

Answer 25

Towards periodontal ligament (vascular)

Question 26

Can the cmentocytes die in the lacunae?

Answer 26

Yes, when they get too far from the periodontal ligament and there are empty lacunae left Hence why farm in the ground section

Question 27

Are cementocytes active or inactive?

Answer 27

No Minute amounts of energy and protein synthesising organelles

Question 28

What are the incremental lines in cementum called?

Answer 28

Incremental lines of Salter

Question 29

What do incremental lines of salter represent?

Answer 29

Mark differences both in mineralisation and in organic matrix composition

Question 30

Are lines of salter regular?

Answer 30

No, especially in cellular cementum

Question 31

What do these lines represent?

Answer 31

Incremental Lines of Salter

Question 32

What is the Tomes’ granular layer?

Answer 32

Results from the looping and branching of the dentino tubules as a result of the branching of the odontoblastic processes

Question 33

Where does the dark line (afibrillar) locate?

Answer 33

Between the hyaline layer and the cementum

Question 34

Answer 34

A = dentino-tubules B = granular layer of tomes’ C = dark line (afibrillar cementum) D = acellular cementum (closely packed lines of Salter) E = cellular F = hyaline layer

Question 35

What are the 2 main sources of the organic matrix?

Answer 35

Extrinsic and intrinsic fibres

Question 36

How do the Sharpey’s fibres enter the cementum?

Answer 36

Perpendicular or slightly oblique to the root surface

Question 37

How do intarsia fires run in relation to the root surface?

Answer 37

Parallel

Question 38

True or Flase, the intrinsic and extrinsic fibres run parallel to one another?

Answer 38

False, run at right angles to one another

Question 39

Answer 39

Decalcified section: A) Dentine, B) Acellular cementum, C)Periodontal ligament (Principal fibres), D) alveolar bone, E) Ginigival epithelium, White arrows pointing to Sharpey’s fibres in alveolar bone

Question 40

Where is the gingiva and the connective tissue of the gingiva?

Answer 40

Question 41

What is this a decalcified section of?

Answer 41

Apex of root

Question 42

Where is the cementum, cellular ad mixed fibre cementum?

Answer 42

Apex of root, cementum neck to the periodontal ligament

Question 43

Answer 43

A) Alveolar bone, B) periodontal ligament, C) Cellular cementum (at the root apex)

Question 44

What is larger, intrinsic or extrinsic fibres?

Answer 44

Extrinsic fibres Sharpey’s fibres

Question 45

Where is the afibrillar cementum found?

Answer 45

Thin layer between hyaline layer and acellular cementum And overlying enamel

Question 46

What type of cementum overlies enamel?

Answer 46

Afibrillar cementum

Question 47

Answer 47

A = Enamel B = dentin C = granular layer of tomes’ D = hyaline layer E = acellular cementum F = afibrillar cementum Ground section

Question 48

What is the origin of the afibrillar cementum?

Answer 48

Epithelial cementum

Question 49

Answer 49

A = dentin B = enamel C = mantle dentin D = acellular cementum E = afibrillar cementum F = hyaline layer White arrow = granular layer of Tomes

Question 50

How would you describe the interaction of cementum and enamel?

Answer 50

Cemento-enamel junction

Question 51

How would you describe the relationship of cementum and dentin?

Answer 51

Cemento-dentinal junction

Question 52

What are the three other structures which cementum interacts with?

Answer 52

Enable Dentin Periodontal ligament

Question 53

What are the 3 possible arrangements of cementum and enamel?

Answer 53

1. Cementum overlaps enamel (60%) 2. Cementum and enamel meet at butt joint (30%) 3. Cementum and enamel fail to meet and the dentin between them is exposed (10%)

Question 54

What type of cementum is formed when cementum overlaps enamel?

Answer 54

Afibrillar cementum

Question 55

What surface f eagle os more highly mineralised?

Answer 55

Aprismatic No prisms

Question 56

Answer 56

A = surface of enamel B = hunter strager bands C = enamel stria or stria of fretsius D = mantle dentin E = interglobular dentin F = dentino-tubules

Question 57

What junction is shown here?

Answer 57

Cementino-dentinal junction

Question 58

Answer 58

A = afibrillar cementum B = Tomes’ C = Dentino-tubules D = acellular cementum E = hyaline / dark line

Question 59

What does the cemento-dentinal junction allow?

Answer 59

Anchors periodontal ligament fibre into dentin

Question 60

Answer 60

Decalcified section: A)Dentine B)Acellular cementum C)Cellular cementum D)Reparative cementum at area of resorption E)Periodontal ligament

Question 61

What can odontocasts resorb?

Answer 61

Dentin Cementum

Question 62

What is a reversal line?

Answer 62

The reversal of activity from resorption to deposition (same as bone)

Question 63

Answer 63

Question 64

What does repair cementum represent?

Answer 64

Cellular cementum Less mineralised Smaller crystals