Microbiology of the RC System Flashcards by sophie rosen

The — provides an
ideal environment for bacterial
colonization

root canal system

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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.

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This area is now largely protected from the

host defenses

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— is the basic science
most closely associated with the
practice of Endodontics

Microbiology

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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

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black pigmented anaerobic G-rods: (6)

• Porphyromonas sp. ( Bacteroides previously)
• Prevotella nigrescens (Bacteroides previously) most frequent in endo
infections
• Peptostreptococcus,
• Fusobacterium
• Eubacterium
• Actinomyces

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Release: Lipopolysaccharides (LPS), also known as endotoxins:
(3)

fever, collagenolysis, osteolysis

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The canal walls/spaces are
conducive to formation of

Biofilm
(complex, colonized communities
of bacteria).
Once introduced, MO thrive there.

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can a single microorganism cause RCT

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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 )

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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

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BIOFILM: Think

complex, variable & constantly
changing bacterial infection

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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.

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— bacteria appear to be the
most common microorganisms in primary
endodontic infections.

Anaerobic Gram –

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Anaerobic Gram –
Common genera: (7)

-Porphyromonas
- Prevotella
- Peptostreptococcus
- Streptococcus
- Actinomyces
- Olsenella
- Propionibacterium

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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.

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Therefore chronic infections within
the RC System tend to favor

anaerobic bacterial flora*

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As a rule — is responsible
for an Endo infection*

NO one
organism

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ALL endo infections are

mixed (polymicrobial)*

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Mostly (2)

facultative and
obligate anaerobes*

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Facultative anaerobes

(Aerobes
which can also survive in an
anaerobic environment) May
become more numerous & virulent
with addition of oxygen.

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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

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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)

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SO . . .
Avoid (2)

leakage of rubber dam or temporary

iatrogenic contamination during
treatment (leaky dental dam, etc.)

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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

1. primary infections:

caused by bugs that initially invade and colonize necrotic pulp tissue within the RCS.

2. 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.

3. 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