12. Periodontal Disease Pathogen Hypothesis

Question 1

LOs

Answer 1

Question 2

Periodontal disease definition

Answer 2

Question 3

Non specific plaque theory
What?
Disadvantages?
Why is this theory still important?

Answer 3

-First theory about the pathogenesis of periodontal diseases was a non specific plaque theory (Miller, 1890; Loesche, 1976; Theilade, 1986)

• Disadvantages
  =not all patients progress from gingivitis to periodontitis and all patients progress at different rates
  = This theory cannot explain differences in pathogenesis of of periodontal diseases between different individuals
• this theory is still v important → current treatment of periodontal disease is not surgical, is still based on this theory (remove supra and sub gingival plaque

Question 4

Specific plaque theory

Answer 4

• development of the anaerobic hood in the 1970s for the first time allowed cultivation of the structure anaerobic species
• diseases are inflammations caused by specific periopathogens

Question 5

Microbiology of periodontal diseases groups

Answer 5

• all bacteria in mouth can be grouped into 5 complexes

Question 6

Differences between gram pos& gram neg bacteria

Answer 6

Question 7

Ecological plaque theory
→why was it developed
→ what

Answer 7

Question 8

Keystone pathogen theory

Answer 8

Question 9

Keystone periodontal pathogen summary diagram

(Go over slides again, 16:20??)

Answer 9

• healthy sites = symbiotic bacteria that live in harmony with host
• this symbiotic bacteria is composed of different species, some is commensal, some are incompatible with inflammation
  -some are pathobions (not pathogenic in healthy mouth BUT if introduce pathogenic bacteria, then this bacteria in low numbers can subvert and impair host immunity) (this immune response will not be able to protect us from this normal symbiotic microbiota
• this now inflammatory response which is not effective against symbiotic microbiota will…
• will lead to changes in composition of subgingival microbiota
• will lead to predominance of pathobions which are present in low v numbers in healthy sites but in the presence of keystone periodontal pathogens
• if immune response not effective, these pathobions can become predominant species and they can result in exaggerated inflammatory response

Question 10

Inflammation mediated polymicrobial emergence and dysbiotic exacerbation (IMPEDE) model

(Go over slides again, 16:20??)

Answer 10

• this theory is similar to previous theory
• highlights the importance of inflammation
• all periodontal diseases can fe explained by this theory

Question 11

Go over last two slides of lecture again?? (16:20)