- Infection occurs when microorganisms invade tissues and produce clinical signs and symptoms of disease. - The root canal system can become infected through dentinal tubules, lateral canals, or pulp exposure providing a reservoir for microbial growth. - Root canal infections are usually polymicrobial, involving both anaerobic and facultative bacteria, and treatment aims to disrupt the microbial ecosystem through debridement and disinfection to eliminate infection and allow healing of surrounding tissues.

2. 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.

3. Portal of entry of microorganisms:
Dentinal tubules
Pulp exposure
Microbes invade the pulp through
Fractures & cracks
Lateral & accessory canals
Blood circulation (anachoresis)

4. 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.

5. 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.

6. 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.

7. 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.

10. 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

11. 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.

12. Chemomechanical RC. Preparation
disrupt & destroy microbial ecosystem.
Perfect obturation eliminate the pulp
cavity as a reservoir.

13. Association of bacteria with periradicular
disease:
Contents of infected canals are potent
irritants periradicular pathosis.
Bacteria &/or bacterial by products
apical periodontitis.

14. Virulence Factors:
Fimbrae (pili).
Capsules.
Extracellular vesicles.
Virulence factors
lipopolysaccharides (LPSs).
Enzymes.
Low-molecular weight products.
Short chain fatty acids.
Polyamines.

15. 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.

16. 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.

17. Correlations with Pathoses & Treatment:
-Endo. infections are polymicrobial.
Excellent collateral circulation.
-Periradicular tissues posses
Lymphatic drainage.
Vast amount of undifferentiated cells.

18. Periradicular pathoses
develop in response of
microorganisms
Microorganisms.
Microbial
by product.
Microbial
breakdown
products.
Inflammatory
mediators.
Instrument trauma.
Chemicals.

19. Acute periapical abscess .
Necrotic tissues.
Phoenix abscess.
Contain
Bacteria.
Suppurative apical
periodontitis.
Numerous PMNs

20. Infection Control:
All patients should be treated as if they have
transmissible disease.
Use physical barriers
Rubber dam
Safety glasses
face shields
Masks
Gowns
Gloves
Disinfect tooth surface & rubber dam with
Chlorhexidine or Na OCL.

21. 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.

22. Debridement of the root canal system:
RC debridement instrumentation +
irrigation.
Flush out debris
Irrigants Dissolve organic remnants
Antimicrobials
Lubricants

23. 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.

24. 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

26. Intracanal Medication (IC):
Microorganisms inside RC. multiply between appts.
Intracanal medicaments exert antimicrobial action
between appts
Intracanal medicaments
(phenolic products).
.
Formocresol.
CMCP & CPCP.
Metacresyl
acetate.
Eugenol .
Thymol.
Cresation.
Phenolics antigenic, cytotoxic & with short
durations.
The current IC. Medicament of choice Ca (oH)2.

27. 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.

28. 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.

29. Symptomatic pulpitis
Apical periodontitis
without systemic
signs & symptoms
Draining sinus tract
Localized swelling
do not
require
antibiotics

30. 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.

31. 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

32. 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.

33. V- Systemic pulmonary shunts.
Vi- Arterio-venous shunts.
Vii -Uncontrolled diabetes.
Viii- Immunosuppressed & immunologically
deficient cases.

34. Medically compromised patients at risk of
bacteremia must receive.
A regimen of antibiotics that follows the
recommendations of
American Heart Association (AHA)

35. 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

36. Signs & symptoms of systemic
iInvolvement & spread infection
Fever 38° c
Malaise
Trismus
Diffuse swelling
Cellulitis
alone or in combination
Antibiotics should be continued for 2 to 3 days after
disappearance of signs & symptoms.

37. 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.

38. 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.

39. 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.

40. Clarithromycin (Klacid)
Clarithromycin a macrolide – a
semisynthetic derivative of erythromycin.
Clarithromycin has
greater antibacterial
spectrum.
less GI upset.
Dose 500 mg/8-12 hours

41. Cephalosporins broad spectrum but does
not include anaerobes.
Cefaclor (2 nd. generation) effective
against anaerobes.
Not recommended for penicillin allergic
patients.

42. 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.

43. Metronidazole
effective against anaerobes
Ineffective against aerobes
Metronidazole + penicillin or other antibiotic
endo.infection.
Dose 250 to 500 mg/ 6 hours.

45. 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.

46. 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.