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Oral Bio > Cementum > Flashcards

Cementum Flashcards

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1
Q

List the types of cementum discussed in your text.

A

Intermediate

True Cementum

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2
Q

Describe each type of cementum given the criteria in your texts.

A 
Intermediate
-from HERS cells (epithelial root sheath)
-seal dentinal tubules
True Cementum
-bone like substance from cementoblasts
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3
Q

Associate each type of cementum with the tooth and with the periodontal space.

A

continuos with the PDL-adherent to the dentin

FINISH

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4
Q

What terms are used to define true cementum

(2)

A
  1. cellular

2. acellular

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5
Q

Compare cementum with the other types of mineralized tissues.

A

Cementum is mineralized periodontal support tissue-as is alveolar bone. Cementum is ~50% mineralized

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6
Q

Microscopic components of acellular cementum (2)

A
  1. no cementocytes - but still contain both fiber types

2. cementoid

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7
Q

The process of cementum formation - cementogenesis (3)

A
  1. begins at root formation
  2. continues throughout life
  3. can be a reparative process in root resorption
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8
Q

Intermediate Cementum

  • Substance?
  • Produced when?
  • Location?
  • Formed from?
  • Thickness?
  • Produced by?
  • Mineralization compared to cementum, dentin, and enamel?
  • Protein?
A

There is a mineralized substance produced during formation of the tooth root.

In the developed root, this substance is located between the granular layer of Tome’s and the true cementum.

When the microanatomy of the tooth had been first described, it was assumed (incorrectly) that the cells which form cementum also formed this substance.

Unfortunately, this substance is called intermediate cementum.

The layer of intermediate cementum is 10 nm in thickness and is formed by the same cells which produce enamel.

Intermediate cementum, like enamel, is more highly mineralized than either dentin or cementum.

Intermediate cementum, like enamel, contains the enamelin protein group.

How intermediate cementum is formed and its developmental relationship to the root of the tooth will be discussed fully during our consideration of tooth development.

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9
Q

Where is intermediate cementum found?

A

in the developed root it is located between the granular layer of Tome’s and the true cementum

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10
Q

How thick is the layer of intermediate cementum?

A

10nm in thickness

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11
Q

What two dental substances does intermediate cementum separate?

A

the granular layer of Tome’s and the true cementum

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12
Q

What dental tissue does intermediate cementum most closely resemble? How?

A

Closely resembles enamel in its mineralization, protein makeup (enamelin), and is even produced by ameloblasts

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13
Q

What terms are used to define true cementum

(2) and describe them

A
  1. cellular
  2. acellular

*Based on how fast they were formed

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14
Q

What are the microscopic components of cellular cementum?

4

A
  1. cells called cementoblasts produce and mineralize cementum
  2. cells surrounded by matrix called cementocytes whose processes are polarized toward the periodontal space.
  3. hydroxyapatite crystals
  4. an organic matrix called cementoid produced by cementoblasts consisting of ground substance and two types of collagen fibers
    (a) collagenous fibers produced by cementoblasts and are called intrinsic fibers
    (b) collagenous fibers of the periodontal ligament embedded in the matrix are called extrinsic fibers or Sharpey fibers; these are fibers which anchor the tooth in its socket
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15
Q

Cells which are surrounded by matrix and have processes which are polarized towards the PDL

A

Cementocytes

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16
Q

Where are cementocytes found on a histological slide?

A

near the PDL-Cementum

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17
Q

Cells which produce and mineralize cementum

A

Cementoblasts

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18
Q

The Cementoenamel Junction

-Four Different Arrangements

A

NUMBERS DO NOT MATTER!!

  1. Cementum overlaps enamel
    a. (12% Arambawatta 2009, not mentioned in Chiego)
  2. Cementum and enamel exactly meet
    a. (30% Chiego vs 55% Arambawatta)
  3. Cementum and enamel fail to meet Gap
    a. (5-10% Chiego vs ~30% Arambawatta)

**KNOW: gap is responsible for dentin hypersensativity, for bleaching, and for osteoclast to get into bone

b. Potential for root caries / hypersensitivity / external root resorption?

  1. Enamel overlaps cementum
    a. (~1-2% Arambawatta vs 60-65% Chiego)
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19
Q

Physical Characteristics of True Cementum
(3)

Mineralization? Vessels?

A
  1. About 50% mineralized (equal to or slightly less mineralized than bone)
  2. Avascular - making it difficult to heal
  3. Aneural - No Pain - making us unaware of inflammation
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20
Q

The Cementoenamel Junction

-Four Different Arrangements

A

NUMBERS DO NOT MATTER!!

  1. Cementum overlaps enamel
  2. Cementum and enamel exactly meet
  3. Cementum and enamel fail to meet Gap

**KNOW: gap is responsible for dentin hypersensativity, for bleaching, and for osteoclast to get into bone

  1. Enamel overlaps cementum
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21
Q

Physical Characteristics of True Cementum
(9)

Mineralization? 
Vessels (2)?
Proteins?
Color?
Resistance to P?
Lifespan
Thickness (2)
A
  1. About 50% mineralized (equal to or slightly less mineralized than bone)
  2. Avascular - making it difficult to heal
  3. Aneural - No Pain - making us unaware of inflammation
  4. Important extracellular glycoproteins (fibronectin, tenascin, vitronectin and osteopontin
  5. Same color as dentin (This poses a problem for procedures such as root planing).
  6. Cementum is MORE resistant than bone to destruction by pressure (Important for orthodontists ).
  7. Cementum is produced throughout life and is effective in repairing horizontal root fractures, but not vertical root fractures
  8. The thickness of cementum varies. Thickness at the cementoenamel junction is about 10-60 microns and increases apically to 200 microns or more at the tip of the apex
  9. Cementum thickness increases with age and may occlude the accessory and apical foramina. Apical vasculature is constricted.
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22
Q

What is the significance of the gap between cementum and enamel

A
  1. Cementum and enamel fail to meet Gap

**KNOW: gap is responsible for dentin hypersensativity, for bleaching, and for osteoclast to get into bone (root caries)

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23
Q

Composition of cementioid

A

2 types of collagen

  • intrinsic fibers
  • Extrinsic fibers
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24
Q

Describe and define the 2 types of collagen which make-up the cementoid

A

intrinsic fibers-collagenous fibers produced by cementoblasts

extrinsic fibers OR Sharpey fibers-collagenous fibers of the PDL embedded in the matrix-Anchor the tooth in its socket

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25
Q

Produces intrinsic fibers

A

cementoblasts

26
Q

Sharpeys fibers

A

Also known as extrinsic fibers collagenous fibers of the PDL embedded in the matrix-Anchor the tooth in its socket

27
Q

When does cementum formation begin

A

At root formation

28
Q

When does cementum formation end

A

goes through life

29
Q

Can root resorption be repaired by the body?

A

Cementum formation can repair root resorption

30
Q

Can root resorption be repaired by the body?

A

Cementum formation can repair root resorption

31
Q
  1. Important extracellular proteins of cementum (4)
A

Glycoproteins (4)

fibronectin
tenascin
vitronectin
osteopontin

32
Q

Color of cementum and clinical significance

A

Similar to dentin which is a problem for root planing

33
Q

Cementum resistance to Pressure and compare to bone-Significance?

A

Cementum is MORE resistant than bone to destruction by pressure (Important for orthodontists ).

34
Q

Cementum is produced throughout life and is effective in repairing what but not what

A

horizontal root fractures, but not vertical root fractures

35
Q

Thickness of cementum

A

The thickness of cementum varies. Thickness at the cementoenamel junction is about 10-60 microns and increases apically to 200 microns or more at the tip of the apex

Cementum thickness increases with age and may occlude the accessory and apical foramina. Apical vasculature is constricted.

36
Q

Cementum-Forming Cells

Cementoblasts

A
  1. Active
  2. Inactive
  3. osteoclast-like cells
37
Q

Cementum-Forming Cells

Cementoblasts

A
  1. Active
  2. Inactive
  3. osteoclast-like cells
38
Q

Cementum forms how? Makeup?

A
  1. A usual rule of thumb is that when cementum forms slowly, it is acellular.
  2. There is usually a thin layer of acellular cementum laid down as the root forms.
  3. When cementum forms more rapidly, cementoblasts are trapped in the matrix and become cementocytes.
  4. Distribution of more acellular cementum is seen near CEJ and more cellular cementum occurs at apex and in furcations.
39
Q

As the root forms what is laid down?

A

a thin layer of acellular cementum

40
Q

What happens when cementum forms more rapidly?

A

Cementoblasts are trapped in the matrix and become cementocytes

41
Q

Distribution of more acellular cementum is seen near where? (2)

A

near the CEJ and more cellular cementum occurs at the apex and in furcations

42
Q

Number of intrinsic fibers

A

few

43
Q

Intrinsic fibers are produced by what? in what?

A

intrinsic fibers are produced by cementoblasts in secretion of cementoid

44
Q

Orientation of intrinsic fibers

A

Parallel to the long axis of the tooth

45
Q

Do acellular and cellular have intrinsic fibers?

A

Yes

46
Q

Extrinsic fibers are more commonly known as

A

PDL fibers

47
Q

What produces extrinsic fibers aka PDL fibers

A

NOT cementoblast, but fibroblast

48
Q

what can be the result of hypercementosis (4)

A
  1. Abnormal O forces
  2. Cementoma
  3. Padget’s disease
  4. Cementicles (attached and free)
49
Q

Apical migration of the gingiva leads to _______

A

Cementum exposure–> will lead to death of cementum since it receives nutrients from capillaries in adjacent CT

50
Q

How does cementum receive its nourishment

A

by diffusion from the capillaries in adjacent CT

51
Q

Exposed cementum may be what?

It is considered what?

A

May be hypo-mineralized

Considered dead

52
Q

Dead, exposed cementum is coated with what

A

exotoxins and endotoxins in crevicular fluid

53
Q

In order for what to happen, dead cementum must be removed

A

soft tissue healing or reattachment-Thus use SRP

54
Q

Define cementicles

A

nodules of cementum produced by cementoblast

55
Q

Three types of cementicles

A

Attached to root

unattached to root

Forming around epithelial remnants in the PDL

56
Q

Clinical significance of cementicles (nodules of cementum)

(2)

3rd but not sure what it has to do with this??

A

Since cementum continues to grow throughout life these nodules may get large enough to cause root resorption of bone by exerting pressure on the bone lining the socket

May occlude the root foramen

Regenerating cementum may be a key to encouraging complete periodontal regeneration. Emdogain aims to accomplish this.

57
Q

What does emdogain aim to accomplish

A

Regenerating cementum by encouraging Periodontal regeneration

58
Q

Aging of Cementum

1. appearance and suceptibility

A
  1. Areas of resorption appear
  2. Occlusion of apical foramen
  3. Susceptible to cemental tears/fractures
59
Q

Tooth wear in terms of cementum

A

Compensatory super-eruption due to cementum deposition at the apex

60
Q

What happens due to cementum deposition at the apex?

A

Compensatory super-eruption

Oral Bio (9 decks)

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