Periodontal pathogens (Oral Microbiology)

Question 1

Periodontal disease definition

Answer 1

Chronic inflammatory disease occurring as a result of infection by accumulating subgingival plaque

Question 2

Gingival environment properties?

Answer 2

• Constantly bathed in gingival crevicular fluid (GCF)
• Contain enzymes, antibodies, proteins, etc.
• Near neutral pH: turns BASIC in diseased state (pH 7.8)
• GCF increase in disease state.

Question 3

Describe microbial involvement in periodontal disease:

Answer 3

• Plaque accumulation causes inflammation
• Removal of plaque restores health
• Certain bacteria show up more commonly in disease sites than healthy
• Bacteria from human periodontal pockets cause inflammation in animal

Question 4

What is the ‘ecological plaque hypothesis’

Answer 4

• A healthy microbiota shifts to a diseased-associated microbiota with environment changes.
• Important to brush teeth to reset the ecological shift to healthy bacteria

Question 5

What is the ‘red complex’ and what bacteria is it composed of?

Answer 5

Cluster of bacteria responsible for gingivitis; found in deep pockets.

• P. gingivalis
• T. forsythia
• T. denticola

Question 6

Describe ‘P. gingivalis’ properties

Answer 6

Keystone bacteria in Red Complex.
- Only small numbers needed to shift microflora into disease-associated.

Virulence factors:
- lipopolysaccharides -> Endotoxin on bacteria cell membrane which causes toxic effects (e.g. cell lysis, fever, septic shock) and Fimbriae.

Proteolytic enzymes: Critical to breakdown proteins for nutrients, destroy host immune proteins, destroy host tissue.
- Gingipains = unique protease for P. gingivalis to break down protein substrate.

Acquires Iron (needed for growth).

Question 7

What are the periodontal disease’s virulence factors?

Answer 7

• Colonize host
• Overcome host defences
• Initiate disease process (i.e. damage host tissue)

Question 8

Define ‘necrotizing periodontal disease’

Answer 8

Associated with spirochaetes and fusiforms bacteria which for fuso-spirochaetal complex

Question 9

Define ‘aggressive periodontal disease’

Answer 9

Rapid bone loss affecting adolescent and young adults; associated with aggregatibacteractinomycetemcomitans; commonly found