Week 9- Endodontic Bacteriology Flashcards
What are the ways of a tooth infection?
- Exposure by attrition or trauma
- Caries
- Periodontal disease
What type of bacteria are present in the oral cavity?
- Highly variable mix of facultative and true anaerobe species.
- Either gram + or -
- In special biotopes (plaque, tongue, root canal, caries etc) a well-organised commensural spectrum of bacteria will develop.
How do bacteria protect themselves?
Produce biofilms
What happens during development of biofilm? Why?
Spectrum of species changes from aerobe to anaerobe (in low area of plaque there is not as much oxygen so bacteria adjust their metabolism to anaerobe conditions)
What is the primary way for bacteria to progress through dentine?
Tubules
What is the size of 1 dentinal tubule and 1 bacteria and how many bacteria can fit in one tubule?
In one dentinal tubule ( 1-2um*), 5-20 bacteria (0.1um*) can fit in.
How does bacterial propagation happen?
Adhesion and multiplication
What bacteria are present in deep dentine lesions?
Facultative and strict anaerobe species (streptococci, lactobacilli)
What does lactobacilli in salivary cultures indicate?
Presence of active dentine lesions
What is pulpitis?
As bacteria arrive in the pulp, they face a functioning system of defence through inflammatory response. A balanced state between attack and defence is created.
What are the steps of pulpitis to necrosis?
- Formation of secondary dentine
- Hyperaemia (blood vessels widen and fill with RBC)
- Acute pulpitis
- Spaces between cells filled with serum
- Blood vessels become permeable for leukocytes
- Micro abscesses
- Necrobiosis (bacteria invade pulp and some areas of pulp may still be vital)
- Necrosis (gangrene, complete destruction of pulpal tissue)
- Development of biofilms at canal walls
What are pulpal biofilms composed of?
- Filaments
- Spirochetes
- May have gram - wall
- Bacteria and yeasts
Why do bacteria create biofilms?
Difficult to get food and oxygen inside structure like pulp. Bacterial species work together by feeding on metabolic products of other species, creating a network of interactions. This helps them survive dire conditions of pulp and attacks from human body.
What is internal infection?
Bacteria from biofilm in pulp infect dentinal tubuli from inside towards outer root surface. Need to remove enough dentine otherwise the tubules will be a reservoir for bacteria and reinfection can occur.
What happens after bacteria invade the pulp?
Bacteria face full power of body’s defense system, triggering inflammation in periapical tissues.
Describe virulence and defense with chronic vs acute apical periodontitis
Chronic apical periodontitis: low virulence, good defence
Acute apical periodontitis/abscess: high virulence, low defence
What happens as pulpitis progresses toward necrosis?
Bacteria can exit out of the apical foramen and create problems in apical PDL.
What conditions arise when balance of virulence and defence is in favour of attacker?
Primary acute apical periodontitis
Secondary acute apical periodontitis
Periapical abscess
What conditions arise when balance of virulence and defence is in favour of defense?
- Chronic apical periodontitis
- Granuloma with Lymphocytes, Plasma Cells, Monocytes & Macrophages
What happens is there is equilibrium of virulence and defence?
Chronic apical abscess with or without development of sinus tract
What % of root canal bacteria can be cultured with conventional methods?
10%
What are methods used to identify root canal bacteria?
- Methods of molecular biology and genetic screening
Will there be a vaccine against endo diseases in future?
No, can’t create vaccine to high spectrum of different species. No specific species is responsible for endo diseases
In a typical root canal how many bacteria are present in canal during initial colonisation?
Mixed flora of only a few species (streptococci and obligate anaerobes)
How doe the bacterial spectrum change as tooth undergoes RCT?
Increase in Gram + cocci
Decrease in Gram - rods
What species are problematic in root canals?
Enterococcus faecalis
Candida albicans
When is E. faecalis most prevalent?
Failed RCT
What are the issues with E. faecalis and C. albicans?*
- Resistant to CaOH
- High penetration into tubuli
- Build biofilms
