Microbiology of the RC System Flashcards
The — provides an
ideal environment for bacterial
colonization
root canal system
The root canal system provides an
ideal environment for bacterial
colonization
why? (4)
The RCS is warm, moist & nutritious (has lots of substrate) and
has a variable but largely anaerobic climate.
This area is now largely protected from the
host defenses
— is the basic science
most closely associated with the
practice of Endodontics
Microbiology
By using a special “anaerobic glove box” technique,
anaerobic bacteria were successfully cultured from the canal
system. He proved that many of the pathological bacteria
found in the RC system are
black pigmented anaerobic G-rods
black pigmented anaerobic G-rods: (6)
• Porphyromonas sp. ( Bacteroides previously)
• Prevotella nigrescens (Bacteroides previously) most frequent in endo
infections
• Peptostreptococcus,
• Fusobacterium
• Eubacterium
• Actinomyces
Release: Lipopolysaccharides (LPS), also known as endotoxins:
(3)
fever, collagenolysis, osteolysis
The canal walls/spaces are
conducive to formation of
Biofilm
(complex, colonized communities
of bacteria).
Once introduced, MO thrive there.
can a single microorganism cause RCT
no
skipped
Progression of RC System Infections
(7)
- Carious Lesion or Trauma opens tubules to
bacterial invasion - 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 RC System
- Infection uses “portals of exit” (apical
foramen and lateral canals) to invade periradicular tissues (apical periodontitis) - Periradicular infection occurs beyond apex
( apical abscess )
BIOFILM must
accomplish 6
things to cause
disease within
the RC System
- MO must adhere to host
surfaces - Obtain nutrients from the host
- Multiply
- Invade tissue
- Overcome host defenses
- Induce tissue damage
BIOFILM: Think
complex, variable & constantly
changing bacterial infection
BIOFILM may be defined as a
multicellular microbial
community characterized by cells that are firmly
attached to a surface and enmeshed in a self produced
matrix of extra cellular polymeric substance (EPS),
usually polysaccharide.
— bacteria appear to be the
most common microorganisms in primary
endodontic infections.
Anaerobic Gram –
Anaerobic Gram –
Common genera: (7)
-Porphyromonas
- Prevotella
- Peptostreptococcus
- Streptococcus
- Actinomyces
- Olsenella
- Propionibacterium
The longer the infection exists
within the RC System, the more
oxygen is consumed by bacterial
activity and the more anaerobic
becomes the RC System
environment.
Therefore chronic infections within
the RC System tend to favor
anaerobic bacterial flora*
As a rule — is responsible
for an Endo infection*
NO one
organism
ALL endo infections are
mixed (polymicrobial)*
Mostly (2)
facultative and
obligate anaerobes*
Facultative anaerobes
(Aerobes
which can also survive in an
anaerobic environment) May
become more numerous & virulent
with addition of oxygen.
Obligate anaerobes
(must have
anaerobic environment to survive),
and cannot survive in an AEROBIC
environment. Would it benefit our
cause to add oxygen? NaOCl
liberates O2
BIOFILM becomes more varied, complex, and
difficult to control when the tooth is further
challenged by (2)
salivary contact or operative
contamination (New BUGS or altered
environment)
SO . . .
Avoid (2)
leakage of rubber dam or temporary
iatrogenic contamination during
treatment (leaky dental dam, etc.)
HOW DO WE DESTROY THEM?
KILL DIRECTLY OR STARVE
THEM OUT
KILL DIRECTLY OR STARVE
THEM OUT (6)
• Bugs must adhere to host
surfaces
• Obtain nutrients from the
host
• Multiply
• Invade tissue
• Overcome host defenses
• Induce tissue damage
OUR MAJOR WEAPONS: CLEANING AND SHAPING with (2)
NaOCl and
INTRA-CANAL MEDICAMENTS
— Sodium Hypochlorite
(NaOCl)
8.3%
Canals have many
ramifications,
anastomoses, fins &
webs and bifurcations
which are
inaccessible
to instrumentation
where MO can hide
Such diverse shapes are resistant to
mechanical shaping; files never reach
ALL spaces in the complex pulpal
system.
Correct use of NaOCl
is extremely
important in
eliminating microorganisms in these
spaces*