Microbiology of the RC System Flashcards
Describe the RCS (as what a microorganism would think)
- warm, moist, nutritious (lots of substrate)
- variable, but largely ANAEROBIC climate
- largely protected from host defenses
Apical periodontitis is considered to be? (2 things)
- a defensive host mechanism
- a biofilm caused disease
This type of necrosis can be seen when there is presence of bacteria in the RCS.
liquefaction necrosis
Many of the pathological bacteria found in the RCS are? Who discovered this?
- black pigmented anaerobic gram- rods
- Sunquist
The most frequent pathogen in endo infections is?
Prevotella nigrescens
Some pathogens found in endo infections include?
- Porphyromonas sp.
- Peptostreptococcus
- Fusobacterium
- Eubacterium
- Actinomyces
Endodontic pathogens release what? These can cause?
- release LPS, aka endotoxins
- can cause fever, collagenolysis, osteolysis
T/F: No single microorganism is responsible for causing apical periodontitis.
true
Progression of RCS Infections
- Carious lesion or trauma opens tubules to bacterial infection.
- Bacteria inflame pulp locally.
- Inflammation may overcome pulpal defenses and localized abscesses may form in coronal pulp.
- Infection increases in pulp and necrosis begins.
- Necrosis involves entire RCS.
- Infection uses “portals of exit” (apical foramen and lateral canals) to invade periradicular tissues (cause apical periodontitis).
- Periradicular infection occurs beyond apex (apical abscess).
6 things biofilm must accomplish to cause disease within RCS
- microorganisms must adhere to host surfaces
- obtain nutrients from the host
- multiply
- invade tissue
- overcome host defenses
- induce tissue damage
Chronic infections within the RCS tend to favor what?
anaerobic bacterial flora
ALL endo infections are considered? They consist of mostly?
- mixed (polymicrobial)
- facultative and obligate anaerobes
Describe facultative anaerobes.
aerobes which can also survive in an anaerobic environment
Describe obligate anaerobes.
must have an anaerobic environment to survive; CANNOT survive in aerobic environment
What does sodium hypochlorite (NaOCl) liberate?
O2
Major weapons in destroying RCS pathogens?
- cleaning and shaping with NaOCl
- intra-canal medicaments
Typical percentage of NaOCl used in endo treatment?
8.3%
A typical case requires about how much NaOCl as irrigant per visit?
10-12 cc.
What is substance has near universal acceptance as an intracanal medication?
CaOH
What is used to seal the RCS after obturation?
gutta percha
Use of antibiotics to relieve pain in endo treatment is?
useless
Systemic antibiotics are useful only in what situations?
- ACUTE periradicular infections
- a patient who is immunologically suppressed
3 subclasses of intraradicular infections
- primary - caused by bugs that initially invade and colonize necrotic pulp tissue within the RCS
- secondary - caused by bugs not present in the primary infection but INTRODUCED into the RCS sometime following professional intervention (iatrogenic by definition)
- persistent - caused by bugs that were members of a primary/secondary infection and in some way, resisted intracanal antimicrobial procedures and were able to endure periods of nutrient deprivation within the RCS (FAILURE of RCS to HEAL)
What type of infection is usually a sequel to untreated intraradicular infection?
extraradicular (AAA or CAA)
The ability to form what has been regarded as a virulence factor.
BIO
Cellulitis with involvement of the submandibular space has the potential to be?
life-threatening
