The Periodontium Anatomy

Question 1

what is the periodontium comprised of?

Answer 1

gingiva
PDL
alveolar bone
cementum

Question 2

what is the function of the periodontium?

Answer 2

attachment of teeth to jaws

effective support during mastication

Question 3

what are the 2 parts the gingiva is divided into?

Answer 3

• Attached

- Free

Question 4

what is free gingiva?

Answer 4

Coronal to the epithelial attachment

Question 5

what is the attached gingiva?

Answer 5

tightly bound to the underlying bone = muco-periosteum

Question 6

function of the gingiva?

Answer 6

attachment between mucous membranes and teeth

prevents bacterial invasion of the underlying periodontal tissues

Question 7

in health where are the gingiva attached to the teeth?

Answer 7

coronal to the ACJ

Question 8

what are the gingiva comprised of?

Answer 8

fibrous CT covered by epithelium

extends from mucogingival junction to the tooth surface

Question 9

what is the basic structure of the oral epithelium?

Answer 9

Stratified squamous epithelium

Keratinocytes (90%) and Non Keratinocytes

Question 10

4 types of clear/non keratinocytes found in the oral epithelium?

Answer 10

Langherhans cells - defense
Melanocytes - pigment melanin
Lymphocytes
Merkel cells - sensory touch receptors

Question 11

4 hisotlogical layers in keratinised epithelium?

Answer 11

1 - basal cell layer
2- prickle cell layer
3- granular layer
4- keratinized layer

Question 12

where does cell division occur in the keratinized areas?

Answer 12

cell division occurs in the basal layer
cells move through the epithelium and shed
as this happens cells increase in size/flatten and keratin is produced

Question 13

what is differentiation?

Answer 13

process packing cells together in the keratinized layer

Question 14

example of non keratinized epithelium?

Answer 14

alveolar mucosa

lacks granular and keratinized layers = intermediate and surface

Question 15

what is an MCG and when are they produced?

Answer 15

mucous coating granules - formed in prickle and granular layers
contains lipids released into intercellular spaces in keratinised/non k = forms barrier to water

Question 16

3 areas of gingival epithelium?

Answer 16

• oral gingival epithelium - faces oral cavity - free/attached
• oral sulcular ep - faces tooth but not attached
  junctional ep - attached to tooth

Question 17

oral gingival epithelium structure?

Answer 17

stratified squamous ep

orthokeratinized - cells flat + no nuclei

Question 18

what is the junction like between the oral gingival epithelium and the underlying connective tissue?

Answer 18

wavy course of connective tissue papillae and rete pegs of the epithelium project into each other

Question 19

describe the sulcular epithelium?

Answer 19

lines sulcus
faces tooth
non keratinized
shallow rete peg pattern
not directly involved in attachment

Question 20

what does the junctional epithelium allow? and how does it do this?

Answer 20

forms epithelial attachment to tooth

by hemi desomosomes anchoring basal keratinocytes to the basement membrane

Question 21

how is the JE formed?

Answer 21

by fusion of the reduced enamel epithelium with the oral epithelium on eruption
moves down tooth as tooth erupts, stabilises near the ACJ

Question 22

where does the JE terminate and what is its cell arrangement like?

Answer 22

terminates coronally in the base of the gingival crevice
JE cells orientate themselves parallel to the tooth
Rapid turnover of cells

Question 23

how does cell division occur in the JE?

Answer 23

division occurs throughout, cells shed into sulcus

Question 24

is the JE permeable?

Answer 24

poorly differentiated and do not synthesize MCG’s

also has large intercellular spaces so is readily permeable

Question 25

what are the 2 main components of gingival connective tissue?

Answer 25

Collagen fibres/Extracellular matrix - produced by fibriblasts highly vascular

Question 26

cell types in gingival CT?

Answer 26

fibroblasts macrophages polymorphs/neutrophils lymphocytes/plasma cells

Question 27

how is collagen arranged?

Answer 27

``` circular fibres trans septal fibres dento gingival dento periosteal crestal ```

Question 28

where do crestsal fibres stem from?

Answer 28

alveolar bone into attached gingiva

Question 29

most common type of collagen in CT?

Answer 29

type 1

Question 30

what is the extracellular matrix in gingival CT?

Answer 30

network of polysachharides and proteins secreted by cells

Question 31

what is the periodontal ligament?

Answer 31

specialized vascular connective tissue continuous with gingiva and pulp derived from dental follicle

Question 32

what is the pdl width?

Answer 32

ranges from 0.15-0.38 thinnest in middle third decreases with age

Question 33

role of the principal fibres in the pdl?

Answer 33

attachment of cementum to bone

Question 34

groups of principal fibres?

Answer 34

``` oblique apical horizontal alveolar crest inter radicular ```

Question 35

cells found in loose connective tissue?

Answer 35

fibroblasts undifferentiated mesenchymal cells defence cells

Question 36

the extracellular matrix binds with water which is important for?

Answer 36

hydrostatic cushion | withstand mastication

Question 37

blood vessels of pdl?

Answer 37

apical vessels perforating/lamina dura gingival vessels

Question 38

what are cementoblasts?

Answer 38

line surface cementum and lay down cementum

Question 39

what are osteoblasts?

Answer 39

line endosteal and periosteal alveolar surfaces, lay down bone

Question 40

what are cementoclasts?

Answer 40

line surface cementum and break it down

Question 41

what are osteoclasts?

Answer 41

line endosteal and periosteal surfaces - breakdown

Question 42

what are oxytalin fibres?

Answer 42

``` unique to pdl elastic insert into cementum run parallel/oblique maintain potency of blood vessels during masticaiton ```

Question 43

what are the cell rests of Malassez?

Answer 43

remnants of epithelial root sheath of hertwig | forms plexus around tooth - prevents ankylosis

Question 44

what is bundle bone?

Answer 44

part of bone where tooth attaches cribiform plate - heavily perforated with vessles/nerves radiopaque lamina dura

Question 45

types of cementum?

Answer 45

cellular | acellular

Question 46

epithelial turnover affected by what hormones?

Answer 46

oestrogen adrenaline corticosteroids

Question 47

what do TIMP's do?

Answer 47

inhibit tissue damage by collagensases