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*
6 FUNCTIONS OF NaOCl
in root canal systems (6)
• Disinfects over time
• Dilutes &
Inactivates toxins
• Dissolves substrate
over time
• Dissolves necrotic
tissue over time
• Flushes & Floats out
Debris
• Lubricates Canal
NaOCl degrades rapidly to NaCl (salt water) in the
canal, therefore must be
replenished @ 3-5 min.
Typical case requires about —
cc. of NaOCl
as irrigant per visit*
10-12
NaOCl must be in contact with shaped
canal a minimum of — minutes after canal
enlarged to #— or larger
30
30
A canal smaller than #30
will seldom if ever allow any irrigant to reach the
apical 1/3
of the canal
Intracanal Medications:
Medications placed within the canal system between
appointments. Intended to increase local anti- microbial action
and to further decrease the microbial challenge within the RC
system.
Historically, many — medicaments were used which were
toxic and damaging to healthy tissue. Some are now recognized
as carcinogenic. These formulations are no longer acceptable for
use (e.g. CMCP, Formocresol, Cresatin, Beachwood Creosote, etc.)
harsh
—: near universal acceptance as the
intracanal medication of choice (esp. in
necrotic cases)
CaOH
CaOH pH
11-12
CaOH
discourages
most microbial growth
CaOH
time
long lasting (effective over extended periods)
CaOH
allergy?
no reported
CaOH
application and removal
easy to apply
remove as a paste
CaOH
available in clinic as
ultracal
SYSTEMIC Antibiotics are USEFUL ONLY IN
ACUTE P-R INFECTIONS (Swelling & Fever) or for
a patient who is immunologically supressed.
Healthy patients without systemic signs and symptoms of
infection but with symptomatic (4) do
not require antibiotics. Just creating —
pulpitis, symptomatic apical
periodontitis, a draining sinus tract, or localized swelling
RESISTANCE
When do we use
antibiotics in
endodontics? (5)
-In conjunction with
definitive
procedures to
debride and drain
-Persistent or
spreading infection
-Systemic involvement
w temperature of 100+
-Medically
compromised
-Pre-med when
indicated
Drainage is accomplished by
I&D (Incision & Drainage) as indicated
(usually fluctuant swelling)
Endodontic infections may be classified according to
(4)
Location, Symptoms (Acute or Chronic), degree of Virulence
or Organization (localized or diffuse & spreading).
LOCATION:
(2)
– Intraradicular
– Extraradicular
• Intraradicular is caused by
bugs colonizing within the RCS
Extraradicular infection is usually a sequel to
untreated intraradicular
infection
extraradicular infection
Characterized by
microbial invasion of the periradicular
tissues resulting in inflammation & infection. AAA or CAA
- primary infections:
caused by bugs that initially invade and
colonize necrotic pulp tissue within the RCS.
- secondary infection caused by
bugs not present in the primary
infection but introduced into the RCS sometime following
professional intervention (secondary to professional intervention;
iatrogenic by definition)
Example of a 2ndary infection is when
symptoms arise in a
previously ASYMPTOMATIC infected tooth if operator allowed R.
Dam leakage or placed leaky temporary.
- persistent infection caused by
bugs that were members of a
primary or secondary infection and in some way , resisted intracanal
antimicrobial procedures and were able to endure periods of
nutrient deprivation within the RCS. (i.e.) FAILURE OF RCT TO HEAL
The ability to form BIO has been regarded as a
virulence factor.
Neighboring cells of different species can produce enzymes such as: (3) that are retained in the biofilm matrix
and can protect other bacteria against antibiotics and host defenses
BLactamase, Catalase and proteinases
Bacterial products contribute to —
virulence
Gram – anaerobes) can cause direct tissue damage & osseous breakdown
by releasing:
– Enzymes (collagenase, chondroitinase and hyaluronidase)
– Endotoxins toxic substances associated with the outer cell walls that are released upon
destruction of cell walls and exotoxins
– Lipo polysaccharide (LPS)-an endo toxin in cell wall of G- bugs
– Peptides/amino acids
Staphylococcus Aureus (aka) S. Pyogenes (Gram +) can
cause serious suppurative infections:
(2)
– This bug is thought to produce penicillinase, a B
lactamase that has the potential to render Penicillin
ineffective*
– Rx Augmentin = Amoxicillin + Clavulanic acid (inhibits
penicillinase)
If bacteria from the infected pulp tissue gain entry into the
periradicular tissue and the immune system is unable to suppress
the invasion, an otherwise healthy patient eventually shows signs
and symptoms of an (2) or both.
Clinically, the patient experiences (3)
acute periradicular abscess, cellulitis,
swelling, fever and mild to severe
pain.
Depending on the relationship of the apices of the involved
tooth to the muscular attachments, virulence factors and
host resistence ,the swelling may be (2)
localized to the vestibule
or may extend into a fascial space (cellulitis).
The cellulitis patient generally will also have systemic
manifestations, such as (5)
fever, chills, lymphadenopathy, headache, and nausea
Because the reaction to the infection may occur very
quickly, the involved tooth may or may not show radiographic
evidence of
a widened periodontal ligament space.
However, in most cases the tooth elicits a positive response to —, and the periradicular area is tender to —. This is a serious (critical Infection) in — plane.
percussion
palpation
fascial
— Attachments are important in relation to where the lesion
“points.”
Muscle
If lesion exits coronal to muscle attachment, it is generally on
attached gingiva or alveolar mucosa and we have a localized abscess,
which is MORE EASILY TREATED (No Systemic Involvement)
Fascial spaces are
potential anatomic areas that exist between the fascia
and underlying organs and other tissues.
Fascial spaces
During an infection, these spaces are formed as a result of
the spread of purulent exudate.
The spread of infections of odontogenic origin into the fascial spaces of
the head and neck is determined by the location of the
root end of the
involved tooth in relation to its overlying buccal or lingual cortical plate
and the relationship of the apex to the attachment of a muscle.
For example, if the source of the infection is a mandibular molar and the
apices of the molar lie closer to the lingual cortical plate and above the
attachment of the mylohyoid muscle of the floor of the mouth, the
purulent exudate
breaks through the lingual cortical plate into the
sublingual space.
If the apices lie below (or apical) to the attachment of
the mylohyoid muscle, the infection spreads into the
submandibular
space.
These infections have the potential to be — if not treated aggressively
lethal
Be especially vigilant with infections of —- when cellulitis occurs in the submandibular space with swallowing difficulty
mandibular molars (especially 2nd & 3rd
Molars)
WHY 2nd & 3rd Molars?
Access from S-M space to Sublingual and Submental spaces ; All 3 are called
(Ludwig’s Angina) and infection in these spaces can be Life Threatening*
This is a cellulitis with involvement of the submandibular space. The infection has
pointed apical to the attachment of the mylohyoid muscle and superior to the
platysma muscle.
(2) is important in controlling the infection. — is indicated.
Incision and drainage
Referral
