Endodontics microbiology
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ENDODONTICS MICROBIOLOGY
BYPROF.MAGED NEGM
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Infection occurs if an organism damage the host & produce clinical signs & symptoms.
Pathogenicity the capacity of organisms to produce disease within the host.
Virulence Degree of pathogenicity in a host.
Stages in development of an endo-infection microbial invasion Colonization multiplication & pathogenic activity.
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Portal of entry of microorganisms:
Dentinal tubules
Pulp
exposure
Microbes invade the pulp through
Fractures & cracks
Lateral & accessory canals Blood circulation (anachoresis)
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Pulpal Reaction to Bacteria: Caries without pulp exposure
chronic pulpal response. Caries with pulp exposure acute
or chronic pulpal response. Pulp exposure Pulp abscess. Pulp
necrosis. Periradicular
inflammation. Pulp exposure without
microorganisms minimal inflammation.
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Polymicrobal infections: Normal oral flora contains more than
350 bacterial species. A relatively small group is isolated from
infected pulp cavities. Infected pulp Mainly
anaerobic bacteria
(strict). Some facultative
anaerobes.
Rarely aerobes.
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No absolute correlation between species of bacteria & endo. signs & symptoms.
Black Pigmented Bacteria( BPB) associated with endo-infections.
Most canals containing BPB associated with acute periapical abscess.
Purulent lesions are induced by strains of BPB.
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Porphyromonas gigivalis
Isolated from acute
infections.
Porphyromonas endodontalis Prevotella intermedia found in
both symptomatic & asymptomatic cases. Yeasts & viruses were also
found in pulp cavity. Even the human immunodeficiency virus
(HIV) was isolated from the pulp.
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Microbal Ecosystem in the Root Canal: Necrotic pulp cavity becomes
a reservoir for microbes. Disintegrated tissues & fluids
nutrients for microorganisms. Nutrients are polypeptides & amino
acids. Nutrients Low 02
tension + Bacterial interactions+
Determine the type of predominant
bacteria
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Growth of anaerobes able to metabolize peptides & amino acids.
Some species produce metabolic byproducts
essential nutrient for other species.
Antagonistic relationships may occur among
bacteria. Some by products (eg. Ammonia)
could be either a nutrient or toxin. Bacteriocins (antibiotic-like proteins)
inhibit growth of other species.
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Chemomechanical RC. Preparation disrupt & destroy microbial ecosystem.
Perfect obturation
eliminate the pulp cavity as a reservoir.
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Association of bacteria with periradicular disease:
Contents of infected canals are potent irritants periradicular pathosis.
Bacteria &/or bacterial by products apical periodontitis.
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Virulence Factors: Fimbrae (pili).
Capsules.
Extracellular
vesicles. Virulence factors
lipopolysaccharides (LPSs). Enzymes. Low-molecular weight
products. Short chain fatty
acids. Polyamines.
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1-Fimbrae synergistic relationship between bacteria.
2-Capsules resistance against phagocytosis.
3-Extracellular vesicles affect host cells & protect bacteria against antibodies.
4-LPSs are endotoxins induce periradicular inflammation.
5-Enzymes spreading factors + proteases that neutralize immunoglobulins.
6-Low-molecular weight products (ammonia & hydrogen sulfide) bacterial nutrients.
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7-Short chain fatty acids propionic, butyric & isobutyric acids.
These fatty acids affect phagocytosis, production of interleukin 1 & intracellular changes.
8-Polyamines putrescine, cadaverine & spermidine.
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Correlations with Pathoses & Treatment:
-Endo. infections are polymicrobial.
Excellent collateral circulation.
-Periradicular tissues posses
Lymphatic drainage.
Vast amount of undifferentiated cells.
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Periradicular pathoses develop in response of microorganisms
Microorganisms.
Microbial by product.
Microbial breakdown products.
Inflammatory mediators.
Instrument trauma. Chemicals.
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Acute periapical abscess .
Necrotic tissues.Phoenix abscess.
Contain
Bacteria.Suppurative apical
periodontitis.
Numerous PMNs
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Infection Control:All patients should be treated as if they
have transmissible disease.
Use physical barriers
Disinfect tooth surface & rubber dam with Chlorhexidine or Na OCL.
Rubber dam Safety glasses face shields Masks Gowns Gloves
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Treatment of endodontic infections:
Removal of source of irritation healing of periradicular lesion.
Source of irritation reservoir of infection (pulp cavity).
Achieved by thorough debridement of root canals.
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Debridement of the root canal system:
RC debridement instrumentation + irrigation.
Flush out
debrisIrrigants Dissolve organic
remnants Antimicrobials Lubricants
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Sodium hypochlorite ( Na OCL 0.5 to 5.25%)
irrigant of choice Na OCL dissolves organic
debris & an excellent antimicrobial agent.
Bacteria stay in fins, irregularities & cul-de-sacs of RC. walls.
Sonic and ultrasonic devices improve the irrigant effects.
Irrigant should be passively delivered with a blunt end needle.
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Smear layer amorphous layer of dentin & other debris + viscous material.
Smear layer plugs dentinal
tubules to a depth of 40mm. It affects permeability. Protects
entraped bacteria . Inhibits penetration of
irrigants & medications..Inhibits penetration of sealers. . Inhibits bacterial
colonization
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Intracanal Medication (IC):
Microorganisms inside RC. multiply between appts. Intracanal medicaments exert antimicrobial action
between appts
Intracanal medicaments (phenolic products).
. Phenolics antigenic, cytotoxic & with short durations.
The current IC. Medicament of choice Ca (oH)2.
Formocresol. CMCP & CPCP. Metacresyl acetate. Eugenol . Thymol. Cresation.
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Drainage: The key to managing an abscess or cellulitis
is drainage. Drainage through the canal & incision
decrease discomfort, toxins & pressure. Incision of indurated swelling releases
Blood.
Serous fluids.
Bacteria & their byproducts . Inflammatory mediators.
Drainage removes these irritants & improves local circulation.
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Adjunctive Antibiotic therapy
Antibiotics are not a
substitute for local treatment. The majority of endo. cases
can be treated without antibiotics. Pain & swelling of endo. origin are
managed by debridement & drainage.
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Symptomatic pulpitis Apical periodontitis
without systemic signs & symptoms Draining sinus tract Localized swelling
do not
require antibiotics
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Prophylactic Antibiotics for Medically Compromised Patients:
Distant infection are high in case of transient bacteremia.
Bacteremia puts medically compromised patients at a great risk.
Transient bacteria can result from apical extrusion of bacteria.
Procedures that may produce bleeding induce bacteremia.
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Procedures that may induce bleeding
Rubber dam
Local injections
Extirpation
Surgical procedures Overinstrumentation
Prior to surgical procedures gum & mucosa should be disinfected with:
Chlorhexidine or iodine-glycerine
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Medicaly compromised patients at great risk of bacteremia include:
i-Rheumatic & congentinal disease.
ii-Prosthetic cardiac valves.
iii-Valvular prolapse & regurgitation.
iv-Previous infective endocarditis.
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V- Systemic pulmonary shunts.
Vi- Arterio-venous shunts.
Vii -Uncontrolled diabetes.
Viii- Immunosuppressed & immunologically deficient cases.
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Medically compromised patients at risk of bacteremia must receive.
A regimen of antibiotics that follows the recommendations of
American Heart Association (AHA)
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Antibiotics used in treatment: Antibiotics are prescribed in conjunction
with endo. procedures. In the reservoir of microorganisms (RC
System) absence of circulation. Therefore antibiotics without endo.
procedures not effective. Antibiotics are prescribed when there is : systemic involvement Persistent
infection Spreading
infection
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Signs & symptoms of systemic
iInvolvement & spread infection
alone or in combination
Antibiotics should be continued for 2 to 3 days after disappearance of signs & symptoms.
Fever 38° c Malaise Trismus Diffuse swelling Cellulitis
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Selection of an Antibiotic Regimen:
Penicillin remains the antibiotic of choice.
Effective against many facultative
& strict anaerobes.
Penicillin Has low toxicity
Inexpensive
However, penicillin is allergic to approx. 10% of humans.
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Adequate blood level of penicillin must be maintained.
Initial oral dose of 1000mg followed by 500 mg/6hours.
Antibiotics + proper endo. procedure signif. improvement within 48 hours.
ALL PRESCRIBED ANTIBIOTICS
MAY BE GIVEN FOR 7 DAYS.
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Erythromycin alternative choice for patients allergic to penicillin.
Erythromycin effective against facultative bacteria.
Erythromycin ineffective against most anaerobes & serious infections.
Adverse effect GI upset ingestion of milk or yogurt gives relief.
Adverse effect transient deafnes.
Dose 1000mg followed by 500mg/6 hours.
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Clarithromycin (Klacid)
Clarithromycin a macrolide – a semisynthetic derivative of erythromycin.
Clarithromycin has greater
antibacterial
spectrum.
less GI upset.
Dose 500 mg/8-12 hours
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Cephalosporins broad spectrum but does not include anaerobes.
Cefaclor (2 nd. generation) effective against anaerobes.
Not recommended for penicillin allergic patients.
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Clindamycin effective gm +ve & -ve
bacteria.
Facultative & strict
anaerobes.
Clindamycin well distributed throughout the body & bones.
Adverse effects long use pseudomembranous colitis.
Dose 150 to 300 mg/6 hours.
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Metronidazole
effective against anaerobes
Ineffective against aerobes
Metronidazole + penicillin or other antibiotic
endo.infection. Dose 250 to 500 mg/ 6
hours.
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Culturing Required when
empirical use of antibiotics is not effective.
Procedure: Rubber dam isolation. Disinfection with Na
OCL or other disinfectant. Access opening with
sterile instruments. Microbial sampling with
sterile paper points or aspiration.
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Aspiration is done with 16 to 20 gauge needle.
In dry canals place a drop of a sterile solution before sampling.
Submucosal swellings should be sampled by aspiration before incision.
Samples are immediately placed in the media.
Antimicrobial irrigating solutions should not be used before sampling.