2b - RFOP specific bacteria

Question 1

What is a periodontal disease?

Answer 1

Bacteria-induced, immune mediated inflammatory diseases of the tissues supporting the teeth

(Since immune mediated - patients immune response can have an impact)

Question 2

Difference between health and diseased periodontal sites?

Answer 2

Question 3

Factors that influence periodontal disease initiation + progression

Answer 3

Answer 4

Question 5

Dental biofilm form recap (yr2)

Answer 5

Question 6

Diff between supra gingival + sub gingival dental plaque

Answer 6

Question 7

Periodontal Tissues Destruction is the cause of?

Answer 7

• Direct action of the microorganisms (20%)
• De-regulated inflammatory (immune) response to dental plaque m.o. (disruption of protective innate immunity or unresolved inflammation) 80%

Question 8

Specific pathogenic bacteria produce antigens, LPS and other virulence factors which cause host immune inflammatory response that produces cytokines and prostaglandins (PGE2) that then damage connective tissue and bone metabolism. This leads to clinical expression of disease initiation and progression. Environmental acquired and genetic risk factors can influence severity of host inflammatory response

Answer 8

Question 9

Bacterial virulent factors have different functions in infectious process
What are they

Answer 9

1) Attachment:
- adhesins

2) Invasion

3) Survival: evasion of host defences:
- exotoxins
- C3, C5, igA proteinases

4) Direct damage
- exotoxins
- enzymes eg Collagenase
- metabolic end products

5) Indirect damage - host inflammatory response:
- lipopolysaccharide
- peptidoglycan
- outer membrane proteins

Question 10

TLR
What do Toll like receptors do?
What TLR recognises:
- LPS?
flagellin?
gram negative bacteria?
Gram positive bacteria?

What happens once TLR recognises?

Answer 10

They recognise different bacterial antigens

TLR 4 recognises:
Gram negative bacteria AND LPS

TLR 5 recognises flagellin

TLR 2 recognises gram positive bacteria

Once TLR recognised it will cause inflammatory response and production of inflammatory cytokines

Question 11

Periodontal pathogens
Porphyromonas gingivalis
What complex is it a part of?
What type of bacteria is it?
What does it use as a growth factor?
Virulence factor?

Answer 11

-“Red complex” by Socransky: P.gingivalis, T.forsythia, T.denticola

Gram negative, anaerobic bacteria

Uses haem as growth factors

Virulence factor:
1) LPS
2) Gingipains - VERY IMPORTANT

P gingivalis has different isoforms that have different inflammatory potential

Question 12

LPS is recognised by :

Answer 12

TLR 4

Once TLR recognises p gingivalis LPS, they activate intracellular pathways to produce pro inflammatory mediators, cytokines, prostaglandins which lead to clinical signs of inflammation

Question 13

1 - What are gingipains?

2 - What do Gingipains do?

Answer 13

1 -

Play a role in the pathogenesis of periodontal disease

Gingipains = ENZYMES - trypsin-like cysteine proteinases produced by Porphyromonas gingivalis.

2 -

• inhibition of phagocytosis
• Uncouple inflammation from phagocytosis + promotes dysbiosis
• cleave C5 which activates c5a receptor

Question 14

Question 15

Cytokines

Proinflammatory
Anti inflammatory
What do each activate and effects?

Answer 15

Question 16

Necrotising periodontal disease

Clinical characteristics?
Predisposing factors?

Answer 16

Clinical characteristics: gingival necrosis, “punched-out” papillae, gingival bleeding, pain, fetid breath and pseudomembranes.

Predisposing factors: emotional stress, poor diet, smoking, immunodeficiencies

Question 17

Microbiology of necrotising periodontal disease

Answer 17

Fusospirochaetal infections

T denticola = red complex
F nucelatum = orange complex

Question 18

Features of necrotising disease
What did it usesd to be called

Difference between localised and generalised

Answer 18

Question 19

What bacteria are present in necrotising peridontitis?

Answer 19

Question 20

Aggregatibacter actinomycetemcomitans

1- What is it

2 - Virulence factors?

Answer 20

1 -

Gram-negative, capnophilic (CO2 loving), coccobacillus

Grow in star shaped colonies

2 -

Virulence factors:
- Several adhesins (bind to epithelial cells and collagen)
- Leukotoxin (apoptosis, degranulation, lysosome-mediated cell death)
- Cytolethal distending toxin (cell-cycle arrest)
- Penetration (epithelial cells, fibroblasts)