PDL

Question 1

how to tell diff between ppl and cementum fibres

Answer 1

pdl fibres thicker and widely spread

Question 2

how is pdl inserted into bone

Answer 2

osteoclasts enable remodelling

Question 3

is pdl mineralised

Answer 3

no

Question 4

what is pdl

Answer 4

non mineralised connective tissue between AV and cementum

Question 5

5 cells in pdl

Answer 5

1. fibroblasts
2. non collagenous proteins
3. cementblasts and osteoclasts
4. ERM
5. macrophages
6. osteoclast and odontoblast

Question 6

location of non collagenous proteins

Answer 6

between principal collagen fibres

Question 7

2 non collagenous proteins that form ground space

Answer 7

glycoproteins and proteoglycans

Question 8

fibroblasts role

Answer 8

synthesise and degrade collagen fibres
–fibroblasts have lot of rough end reticulum for transport of proteins
-repsonsible for high rate of protein turnover

Question 9

how do fibroblasts degrade collagen fibres

Answer 9

-lysosomes fuse with phagosomes containing collagen fibrils
-phago-lysosomes degrade collagen fibrils

Question 10

why does fibroblasts have a lot of rough end ret

Answer 10

production and exportation of proteins

Question 11

role of rests of malasezz/ epithelial cell rests

Answer 11

remnants of HERS, have no particular role, may divide to form cysts
-hey may have important functions in the homeostasis of the periodontal ligament and may help to maintain the integrity of the PDL space.

Question 12

role for macrophage

Answer 12

monocyte deritivative, act as defence system

Question 13

4 fibres that make up pdl

Answer 13

collagen
oxytalan
elastin
eluanin

Question 14

what is collagen type 3 called

Answer 14

reticulin fibres

Question 15

collagen type 1 role

Answer 15

70%
assembles into principal fibres
contains non collagenous proteins
assembles and controls orientation of fibres

Question 16

principle collagen fibres

Answer 16

fibres group that show diff orientations at Dif regions of ligament

Question 17

5 variations of principle fibres

Answer 17

1. dento-alveolar crest fibres
2. horizontal fibres
3. oblique fibres
4. apical fibres
5. interradicular fibres

Question 18

role of reticulin (Coll type 3) fibres

Answer 18

cross link to aid tissue support
-for rapid turnover

Question 19

2 fibres that associate with blood vessels

Answer 19

1. elastin- walls of blood vessels
2. elanuanin- around blood vessels to provide mechanical protection

Question 20

3 functions of PDL

Answer 20

-protects dental tissue from excessive occlusal loads
-resists displacing forces
-contains essential cells to form, maintain and repair AV bone

Question 21

pdl tooth support mechanism

Answer 21

-biphasic response to axial loading
-load dissipated through oblique fibre system
-uses compression and fluid flow to resist forces

Question 22

what is biphasic phase

Answer 22

visco-elastic

Question 23

4 tissues of periodontium

Answer 23

-AV bone
-pdl
-lamina propria
-cementum

Question 24

what is lamina propria

Answer 24

connective fibrous tissue that forms bundles to support free gingiva
-forms fibres that link gingiva to AV bone and teeth

Question 25

what is gingival cuff

Answer 25

region of attatchment of gingiva to tooth

Question 26

junctional epithelium

Answer 26

non keratinised epithelium that attaches gingiva to tooth -forms an epithelial collar that surrounds the cervical part of the crown and extends from the base of the gingival crevice to the cementum-enamel junction or CEJ.

Question 27

structure of junctional epithelium

Answer 27

2 basal lamina, one on each side- face the tooth and lamina propria -connect to enamel and lamina propria via hemidesmosomes

Question 28

why are sharpens fibres partly mineralised

Answer 28

mineralised within the cementum but not within the PDL

Question 29

which aspect of sharpeys fibres are larger

Answer 29

AV bone

Question 30

which aspect of sharpens fibre numerous

Answer 30

cementum

Question 31

blood supply to pdl

Answer 31

arteries from AV, pulp and gingiva supply ligament with nutrition capillary volume is high

Question 32

how are capillaries specialised

Answer 32

fenestrations

Question 33

how capillaries between av bone and cementum communicate

Answer 33

volksmann canals

Question 34

average width of periodontal space

Answer 34

0.25mm

Question 35

junctional epithelium function

Answer 35

It has some unique features including: 1. a rapid rate of turnover and 2. is permeable to both gingival crevicular fluid (GCF) and host defence cells. It therefore facilitates defence of the underlying tissue against bacterial invasion.

Question 36

compare pdl and lamina propria

Answer 36

Compared to the periodontal ligament, lamina propria extracellular matrix has less ground substance and less type III collage. It also has a lower turnover rate.

Question 37

Periodontal ligament nerves:

Answer 37

The nerve fibres supplying the PDL are of two types: sensory and autonomic

Question 38

sensory pdl nerves

Answer 38

1. The sensory fibres are associated with nociception and mechanoreception.

Question 39

autonomic pdl nerves

Answer 39

2. The autonomic fibres are associated with the supply of the periodontal blood vessels

Question 40

PDL mechanoreceptors

Answer 40

play an important role in the transmission of touch and textural information during mastication. They also provide afferent feedback essential in the control of salivation, mastication and swallowing.

Question 41

Periodontal blood supply:

Answer 41

The periodontium has a very rich blood supply derived from the superior or inferior alveolar arteries. The majority of capillaries within the ligament have their origin in the intra-bony spaces within the alveolus. The capillaries and arterioles within the ligament form a plexus around the tooth which is primarily situated towards the socket wall, between the principal fibre bundles, and may occupy up to 50% of the periodontal space. This is an extremely high percentage volume compared to other adult connective tissues.

Question 42

how much oxytalan

Answer 42

3%

Question 43

what is oxytalan?

Answer 43

extracellular fibre composition

Question 44

how is oxytalan arranged on outer pdl

Answer 44

on the outer part of the ligament these fibres run obliquely down from the cementum to terminate in the vicinity of the periodontal capillaries.

Question 45

how is oxytalan arranged inner pdl

Answer 45

Within the periodontal ligament proper they tend to be more longitudinally oriented, crossing the oblique fibre bundles more or less perpendicularly.

Question 46

oxytalan function

Answer 46

There is no clear idea as to their function although it has been suggested that these fibres might aid fibroblast migration in the periodontal ligament.

Question 47

oxytalan composition

Answer 47

that they are immature elastin fibres or 'pre-elastin' in that, unlike mature elastin, there is no central amorphous core.

Question 48

foetal like properties

Answer 48

-like foetal -Unlike other adult connective tissues, the PDL has a high rate of turnover of the extracellular matrix -high proportion of type III collagen. -Its high cellularity and the presence of oxytalan fibres are also unusual.