Cementum

Question 1

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:

Answer 1

a mineralised tissue covering the root of the tooth

the cementum enamel junction

the apex

avasular

non innervated

is less than dentin

light yellow

Question 2

Chemical composition

Inorganic:organic

inorganic is:

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

Answer 2

65% inorganic 23% organic 12% water

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

fluoride

Question 3

Organic matrix:

contain

Answer 3

collagene and noncollagene proteins

Question 4

collagen protein :

Most present

other types

Answer 4

type 1

3/5/6/12

Question 5

4 Subtypes of Cementum

Answer 5

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

Question 6

Cementogenesis

Answer 6

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

Question 7

Initial Cementum Layer Characterisics

Answer 7

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

Question 8

After primary deposition…

Answer 8

• 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

Question 9

Formation of Secondary Cementum

Answer 9

• 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

Question 10

Types of Cementum

Answer 10

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

Question 11

How Cementum is Subclassified

Answer 11

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)

Question 12

Organic components include

Answer 12

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

Question 13

Cementum contains ____ minerals than dentin and bone

Answer 13

less

Question 14

function of cementum

Answer 14

• 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

Question 15

_______ is laid down through out life

Answer 15

cementum

Question 16

cementum is _________________ in origin

Answer 16

ectomesenchymal (neural crest origin)

Question 17

is cementum avascular or vascular?

Answer 17

avascular

Question 18

avascular means

Answer 18

no holes for vascular bundles to get through

Question 19

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:

Answer 19

CEJ

apically

apex

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

Question 20

cementoblasts

Answer 20

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

Question 21

cementoblasts are derived from …

Answer 21

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

Question 22

all cells in the dental follicle are derived from ______________

Answer 22

ectomesenchyme (neural crest cells)

Question 23

differentiation is initiated with disruption of _________ __________ tooth sheath.

Answer 23

henrtwigs epithelial

Question 24

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

Answer 24

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

Question 25

histologic features of cementum

Answer 25

- depositional lines - reversal lines - cementoblasts - cementocytes (lacunae, canaliculi) - sharpey's fibers (PDL)

Question 26

depositional and reversal lines both indicate

Answer 26

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

Question 27

cementocytes include

Answer 27

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

Question 28

sharper's fibers (PDL)

Answer 28

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

Question 29

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

Answer 29

60 30 10

Question 30

abfraction

Answer 30

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

Question 31

cementicle

Answer 31

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

Question 32

cementicle can be classified as

Answer 32

free, attached, or embedded

Question 33

cementicles are a response to

Answer 33

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

Question 34

attached cementum embedded cementum

Answer 34

inside cellular layer of cementum covered by layer of epithellial

Question 35

significance of cementum in periodontal disease

Answer 35

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. )

Question 36

hypercementosis

Answer 36

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.

Question 37

toot resorption and repair

Answer 37

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

Question 38

cementum accessory canals define

Answer 38

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

Question 39

cellular, instrinsic fiber cementum .... loctaed.... may be covered over...

Answer 39

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)

Question 40

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 ........

Answer 40

acellular cementum cellular cementum cementocytes resorption.

Question 41

...................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.

Answer 41

Cementoblasts unmineralised matrix (pre-cementum)

Question 42

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

Answer 42

lines of Salter

Question 43

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 ..............

Answer 43

Sharpey’s fibres. ‘extrinsic’ fibre x2 ‘intrinsic’ cementum cementoblasts fibroblasts.

Question 44

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.

Answer 44

Sharpey’s fibres

Question 45

Acellular, extrinsic fiber cementum is Plays a major role in..... loctaed.....

Answer 45

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

Question 47

Acellular, afibrillar cementum produced by typically found

Answer 47

mostly comporised of a minerlised matrix, without ddetactable collagen fibrils or cementocytes exclusively by cementoblasts coronal cementum on human teeth

Question 48

Cellular mixed fiber cementum found

Answer 48

the minerlised collgen fibers run a more irregular course apical third of the root and in furcations