Risk Factors: Specific Bacteria

Question 1

What are the two main microbiological differences between healthy and diseased sites?

Answer 1

1. Types of bacteria
   - More gram negative, anaerobic bacteria
2. Host immune response
   - Inflammation is uncontrolled leading to tissue destruction

Question 2

What are the 3 prerequisites for PDD?

Answer 2

1. Virulent Pathogens
   - Virulence factors: adhesins, invasion factors, co-aggregation
2. Local Environment
   - Lower oxygen tension
3. Host Susceptibility
   - Gene polymorphism, smoking, diabetes, immunosuppression

Question 3

Summarise how the dental biofilm forms

Answer 3

1. Formation of acquired pellicle formed of adhesion to saliva glycoproteins, proteoglycans onto the tooth surface
2. Adhesion of the pioneer species such as Streptococci attaching to pellice and produce extra-cellular polysaccharide
3. Bridging species allowing late colonisers to attach

Question 4

What are the main differences between the supra and sub gingival biofilm?

Answer 4

Supra:
- Nutrients from saliva and diet
- Carbohydrates are main energy source
- Firmy attached
- Higher oxygen tension: aerobes

Sub:
- Nutrients from GCF
- Motile forms
- Anaerobic bacteria
- Reduced oxygen tension

Question 5

What is the key stone theory to PDD?

Answer 5

Acquired pellicle starts on the tooth surface and ecological growth promotes the growth of key stone species. These species induce impairment of the host protective mechanisms. This leads to overgrowth of dental biofilm and exacerbated inflammation and periodontal tissue damage.

Question 6

Name some examples of virulence factors that bacteria may have

Answer 6

Adhesins to attach to tooth tissue.
Invasion factors - flagella, enzymes (collagenase, fibrinolysin).
Survival enhancement - producing different immunoglobulin proteases, cytotoxin production
Direct damage - exotoxins, enzymes, metabolic end products
Indirect damage (caused by host response) - lipopolysaccharides, lipoproteins, DNA, peptidoglycan)

Question 7

Name some examples of virulence factors that bacteria may have

Answer 7

Adhesins to attach to tooth tissue.
Invasion factors - flagella, enzymes (collagenase, fibrinolysin).
Survival enhancement - producing different immunoglobulin proteases, cytotoxin production
Direct damage - exotoxins, enzymes, metabolic end products
Indirect damage (caused by host response) - lipopolysaccharides, lipoproteins, DNA, peptidoglycan)

Question 8

How does the immune system recognise all these pathogens?

Answer 8

Toll-like receptors. Each of these recognise different bacterial antigens such as LPS, flagella, membrane types and raw components.

Question 9

P.Gingivalis:
1. Gram + or -?
2. Aerobic or anaerobic?
3. What is the main virulence factor?

Answer 9

1. -
2. Anaerobic

Question 9

P.Gingivalis:
1. Gram + or -?
2. Aerobic or anaerobic?
3. What is the main virulence factor?

Answer 9

1. -
2. Anaerobic
3. LPS (component of outer membrane in gram - bacteria)

Question 10

Once toll receptors recognise LPS in gram - bacteria, what happens inside the immune cells?

Answer 10

Production of different pro-inflammatory mediators, prostaglandins and cytokines.

Question 11

Why does our body become inflamed as a protective response?

Answer 11

To clear the damaging pathogen or any invading pathogens

Question 12

How does P.Gingivalis overcome the host inflammatory response?

Answer 12

• It uncouples inflammation from phagocytosis to promote dysbiosis
• Inhibition of phagocytic cells promotes dysbiosis in the sub-gingival dental biofilm
• Other bacteria can then grow and cause further inflammation

Question 13

What are the 3 main pro-inflammatory cytokines produced by macrophages, fibroblasts and epithelial cells?

Answer 13

IL1, IL6, IL8

Question 14

What are some of the characteristics of necrotising periodontal disease?

Answer 14

• Gingival necrosis
• Punched out papillae
• Gingival bleeding
• Pain
• Bad breath
• Pseudomembranes

Question 15

What are the families of the two bacteria present in necrotising periodontal disease?

Answer 15

1. Fusobacteria
2. Spirochaetes

Question 16

What is aggressive periodontitis and what is the difference between it being localised and generalised?

Answer 16

Rapid attachment loss and bone resorption
Familial aggregation

LOCALISED : Circumpubertial onset (around puberty), first molars and incisors affected with no more than two other teeth, robust serum response to infecting agents
GENERALISED : Affects at least three permanent teeth other than first molars and incisors, usually affects people <30, poor serum response to infecting agents, episodic nature

Question 17

For patients who have aggressive periodontitis, what do they typically tend to have?

Answer 17

Peripheral blood neutrophil impairment - the neutrophils cannot react to chemotactic stimuli.