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I.O.E Dental anatomy and Histology > Cementum > Flashcards

Cementum Flashcards

1
Q

cementum is……………

It begins at…………

and contiunes to………..

does not contain anyblood vessels neaning it is ………

contains no nerves so it is……………

The hardness of cementum:

colour:

A

a mineralised tissue covering the root of the tooth

the cementum enamel junction

the apex

avasular

non innervated

is less than dentin

light yellow

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2
Q

Chemical composition

Inorganic:organic

inorganic is:

Trace elements such as ………… . the cementume has the highest concentration of this out of all the tissues

A

65% inorganic 23% organic 12% water

calcium (ca) and phospahte (Ph) that form the hydroxy appitite crystals

fluoride

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3
Q

Organic matrix:

contain

A

collagene and noncollagene proteins

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4
Q

collagen protein :

Most present

other types

A

type 1

3/5/6/12

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5
Q

4 Subtypes of Cementum

A
  1. Primary Acellular Extrinsic Fiber Cementum
  2. Secondary Cellular Intrinsic Fiber Cementum
  3. Acellular Afibrillar Cementum
  4. Mixed Fiber Cementum
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6
Q

Cementogenesis

A

-Ones HERS fragments, dental follicle is exposed to root surface/dentin -> causes differentiation into Cementoblasts at outer surface of root

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7
Q

Initial Cementum Layer Characterisics

A
  1. Acellular
  2. Forms slowly as tooth erupts
  3. Covers the coronal 2/3 of the root
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8
Q

After primary deposition…

A
  • Cementoblast activity slows
  • Fibroblasts of developing Perio Lig. then intertwine collagem around existing fibers protruding from primary cementum
  • Deposit mineral onto root surface -> leads to establishment of Sharpey’s Fibers that attach tooth to Perio Ligament
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9
Q

Formation of Secondary Cementum

A
  • Additional cementum produced after tooth reaches occlusion
  • More rapid deposition of less mineralized cementum along apical 1/3 of root and Interradicular areas of multirooted teeth
  • Collegen fibers in this cementoid ad Parallel to root
  • Matrix vessicles from cementoblasts then mineralize the cementoid
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10
Q

Types of Cementum

A
  1. Acellular - provides attachment to PDL
  2. Cellular - contains Cementocytes. Formed in response to minor persistant trauma and/or tooth wear
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11
Q

How Cementum is Subclassified

A
  1. Time of formation (primary vs. secondary)
  2. Presence of cementocytes (acellular vs. cellular)
  3. presence of collagen fibrils (fibrillar cementum/Afibrilliar)
  4. Origin of its collagen components (intrinsic vs. extrinsic)
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12
Q

Organic components include

A
  • type 1 collages (intrinsic and sharpeys fibers)
  • proteoglycans
  • glycosaminoglycans
  • phosphoproteins
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13
Q

Cementum contains ____ minerals than dentin and bone

A

less

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14
Q

function of cementum

A
  • attachment for the PDL (through sharpens fibers)
  • may provide limited compensation for occlusal wear through continuous apical apposition
  • may participate in repair of root fracture
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15
Q

_______ is laid down through out life

A

cementum

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16
Q

cementum is _________________ in origin

A

ectomesenchymal (neural crest origin)

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17
Q

is cementum avascular or vascular?

A

avascular

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18
Q

avascular means

A

no holes for vascular bundles to get through

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19
Q

cementum is thinnest at the _____

cementum gets more cellular and thicker in which direction of the root?

cementum is thickest at what point

thickness of cementum at
CEJ:
Mid-root:
Apex:

A

CEJ

apically

apex

CEJ: 30-50
Mid-root: 90-150
apex: 150-300

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20
Q

cementoblasts

A

cells responsible for the creation of cementum
- cells responsible for secretion of the organic matrix of cementum

21
Q

cementoblasts are derived from …

A

the inner zone of the dental follicle. come from undifferentiated mesenchymal cells that originate in proximal (inner) zone of the dental follicle.

22
Q

all cells in the dental follicle are derived from ______________

A

ectomesenchyme (neural crest cells)

23
Q

differentiation is initiated with disruption of _________ __________ tooth sheath.

A

henrtwigs epithelial

24
Q

when the disruption of henrtwigs epithelial tooth sheath happens, what happens?

A

allows the undifferentiated mesenchymal cells to make contact with the adjacent dentin.

25
Q

histologic features of cementum

A
  • depositional lines
  • reversal lines
  • cementoblasts
  • cementocytes (lacunae, canaliculi)
  • sharpey’s fibers (PDL)
26
Q

depositional and reversal lines both indicate

A

incremental growth, and run longitudinally.

Both indicated incremental growth
- Run from crown down to the apex
- Indicate growth by laying down collagen
Mineralization of ground substances

27
Q

cementocytes include

A

lacunae (space occupied by the cell)
- canaliculi (space occupied by cytoplasmic projections) can connect together to help cells coordinate reparative functions.

28
Q

sharper’s fibers (PDL)

A

Incretions of pdl into the cementum so it allows connection of bone to cementum- keep tooth in periodontal space

29
Q

Cementum CEJ overlap ___ %
end-to-end = ____ %
gap = ____ %

A

60
30
10

30
Q

abfraction

A

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 of eccentric occlusal loads
31
Q

cementicle

A

calcified bodies appearing or in the cementum and in the PDl.

32
Q

cementicle can be classified as

A

free, attached, or embedded

33
Q

cementicles are a response to

A

local trauma or hyperactive occlusion and appear in increasing numbers with increasing age

34
Q

attached cementum

embedded cementum

A

inside cellular layer of cementum

covered by layer of epithellial

35
Q

significance of cementum in periodontal disease

A

when cementum is exposed it becomes hyper mineralized which prevents reattachment of collagen

  • exposed cementum facilliates attachment of plaque and calculus
  • exposed cementum facilitates endotoxin absorption

(
But it is not so mineralized that its smooth. Still has insertion points for sharpys fibers. )

36
Q

hypercementosis

A

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

etiology is variable. could be from occlusion, periodical inflation, or compensation for occlusal attrition.

37
Q

toot resorption and repair

A

Excess ortho, occ trauma can cause root resorption

Once what is causing it is removed it can repair itself

Lateral canals inside the root. Allow for vascular and growth factors to stimulate cementoblasts on the outside to repair areas of resorption

38
Q

cementum accessory canals define

A

Allow vascular tissues to reach the apical mineralized tissues. Extra nutrients and growth factors is all it needs to stimulate cemento blasts for reapirs

39
Q

cellular, instrinsic fiber cementum ….

loctaed….

may be covered over…

A

this cementum contains cementocytes in a matrix composed almost exclusively of intrinsic fiber cementum

almost exclusively at sites of cemntum repair

by extrinsic or mixed fiber cementumb(both of which are able to provide new anchoridge)

40
Q

The ,…………………….. is the first formed cementum and forms a relatively thin covering over the whole root.

The …………….forms later, predominantly at and around the root apex. It contains entombed cells call ……….(hence the term ‘cellular’).

Unlike bone, it is not normally subject to ……..

A

acellular cementum

cellular cementum

cementocytes

resorption.

41
Q

……………….line the cementum surface. These are cementum forming cells and are traditionally considered part of the periodontal ligament rather than the cementum.

Between the cementoblast and the mineralised cementum is a pale layer of ………………….. This stays at a constant thickness since more matrix is deposited on its periodontal surface at the same rate as mineral is deposited on its inner surface.

A

Cementoblasts

unmineralised matrix (pre-cementum)

42
Q

Incremental lines can be seen in the cementum – these are the ………….

A

lines of Salter

43
Q

Fibres from the unmineralised periodontal ligament insert into cementum as ………

Such fibres can be tracked into the cementum for some distance. Because this inserted fibre was once part of the ligament it is termed an ……………. The fibre is mineralised within the cementum but unmineralised in the ligament. The mineralised matrix between the …………….. is termed ………….and is formed by the ……………. The extrinsic fibres are formed by periodontal …………..

A

Sharpey’s fibres.

‘extrinsic’ fibre x2

‘intrinsic’ cementum

cementoblasts

fibroblasts.

44
Q

As well as having ………………inserting into cementum, the periodontal ligament also forms Sharpey’s fibres in the alveolar bone. Those in the bone are larger but less numerous than those into cementum.

A

Sharpey’s fibres

45
Q

Acellular, extrinsic fiber cementum is

Plays a major role in…..

loctaed…..

A

a matrix with well defined type 1 collagen, the fibrils are part of the densly pack sharpeys fibers.

tooth anchorage

cervical two-thirds of the root

46
Q
A
47
Q

Acellular, afibrillar cementum

produced by

typically found

A

mostly comporised of a minerlised matrix, without ddetactable collagen fibrils or cementocytes

exclusively by cementoblasts

coronal cementum on human teeth

48
Q

Cellular mixed fiber cementum

found

A

the minerlised collgen fibers run a more irregular course

apical third of the root and in furcations

I.O.E Dental anatomy and Histology (7 decks)

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