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Endodontic Microbiology


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After reading this chapter, the student should be able to:
1. Understand the microbial etiology of apical
2. Describe the routes of entry of microorganisms to the
pulp and periradicular tissues.
3. Recognize the different types of endodontic infections
and the main microbial species involved in each one.
4. Understand the bacterial diversity within infected root
5. Describe the factors involved with symptomatic
endodontic infections.
6. Understand the ecology of the endodontic microbiota
and the features of the endodontic ecosystem.
7. Discuss the role of microorganisms in the outcome of
endodontic treatment.
8. Understand the development and implications of
extraradicular infections.

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Endodontic Microbiology

  2. 2. ▪ The PURPOSE OF ENDODONTIC TREATMENT is to; Eradicate the occurring infection Prevent the microbes from infecting the root canal or peri radicular tissue. ▪ Endodontic infections usually develop after pulpal necrosis or in those cases in which pulp was removed for treatment.
  3. 3. ▪ Apical periodontitis is inflammatory disease of microbial origin caused by infection of root canal. ▪ Bacteria are major microorganisms involved in etiology of apical periodontitis. ▪ APICAL PERIODONTITIS DEVELOPS WHEN FIGHT B/W HOST DEFENSE AND ROOT CANAL BACTERIA OCCURS WHICH RESULT IN INFLAMMATION OF PERIAPICAL AREA. ▪ After death of pulp, host defense is lost, then after this, bacteria in root canal form biofilms (similar to dental caries) which in result damage the periapical area.
  4. 4. ROUTES OF ROOT CANAL INFECTION ▪ Normally, dentine & pulp are sterile and is covered by enamel & cementum which prevent the entry of microorganisms. ▪ Microorganisms can reach the pulp when these protective coverings (enamel & cementum) are lost due to following reasons. ▪ Microbes which can damage the pulp and can lead to apical periodontitis comes from following sources; ▪ Oral cavity ▪ Periodontium ▪ Systemic root ▪ Bacteria reach at pulp through following routes; ▪ Dentinal tubules ▪ Lateral or apical foramina ▪ Systemic roots
  5. 5. ▪ Bacterial invasion of dentinal tubules occurs more rapidly in non – vital teeth than in vital teeth. ▪ But if the dentine thickness is very small, permeability to microbes is increased because of larger diameter of tubules near the pulp. ▪ In non-vital pulp above mentioned things does not occur & necrotic pulp is best environment for bacteria. ▪ EFFECTS OF VITALITY OF PULP; ▪ Outward movement of fluid in exposed dentinal fluid prevent the diffusion of microbes. ▪ Tubular contents also decrease the dentinal permeability to microbes; ▪ Collage ▪ Crystals ▪ Host defense molecules ▪ Antibodies ▪ Dentinal sclerosis, reparative or reactionary, smear layer also prevents the diffusion of microbes. ▪ These effects are produced only when the pulp is vital.
  6. 6. DIRECT PULP EXPOSURES It is most noticeable route of endodontic infection. Caries (most common) Trauma Restorative procedures Scaling & root planning Attrition or abrasion Naturally absent Congenital anomalies • Dens invaginates • Dens evaginatus • Palatal groove defects
  7. 7. PERIODONTAL DISEASE ▪ Microbes in subgingival biofilms reach the pulp thorough ▪ Dentinal tubules ▪ Lateral, apical or furcation canals. ▪ Pulp necrosis due to periodontal disease develop only when periodontal pocket reaches the apical foramina which damages the vessels penetrating through apical foramina.
  8. 8. ANACHORESIS ▪It is a process by which microorganisms are transmitted in the blood or lymph to an area of tissue damage. ▪There is no clear evidence that this process cause root canal infection.
  9. 9. MICROBIOTA OF ENDODONTIC INFECTION CLASSIFICATION OF ENDODONTIC INFECTION ▪ Extra radicular infection ▪ Intra radicular infection ▪ Primary infection ▪ Secondary infection ▪ Persistent infection • Asymptomatic apical periodontitis • Dialister invisnus • Bacteroids. • Symptomatic Apical Periodontitis • Treponema Denticola • Acute Apical Abscess • Porphyromonas Endodonticalis, • Treponema Denticola The different types of endodontic diseases contain different types of microbes.
  10. 10. PRIMARY INTRA RADICULAR INFECTION (VIRGIN INFECTION) ▪These are those microorganisms which initially invade & colonize the necrotic pulp tissue. ▪ These organisms may be those which initially infected the pulp and resulted in inflammation & then necrosis. OR these organisms may be late comers which arrive as soon as pulp necrosis.
  11. 11. PRIMARY INTRA RADICULAR INFECTION (VIRGIN INFECTION) ▪ Primary infection is caused by mixed group of bacteria; gram +ve, gram -ve & others. ▪ Composed of 10 – 30 bacterial species & 103 – 108 bacterial cells per canal.
  12. 12. PERSISTENT & SECONDARY ENDODONTIC INFECTIONS. ▪ Persistent endodontic infections; these are those microbes which survive in root canal after intra canal antimicrobial procedures. ▪ Secondary Endodontic Infection; these are those microbes which occupy the root canal during or after professional intervention of root canal (RCT). ▪ They can be oral or non-oral bacteria depending on source.
  13. 13. •Loss or leakage of restorative material. •Tooth fracture. •Opened teeth for drainage of abscess. SOURCE OF MICROBES BETWEEN APPOINTMENTS
  14. 14. Gram Positive Bacteria are Most Common Persistent Bacteria.
  15. 15. E. faecalis facultative anaerobic gram positive coccus (30 – 90% cases) & Candida infections (3 – 18% cases) are found more commonly in root canal treated teeth in post treatment apical periodontitis (Secondary Intra Radicular)
  16. 16. EXTRA RADICULAR INFECTIONS ▪Extra radicular infections are characterized by, microbial invasion & proliferation in the inflamed peri radicular tissue as a result of intra radicular infections. ▪The most common form of extra radicular infection is acute apical abscess.
  17. 17. EXTRA RADICULAR INFECTION CAN BE CAUSED BY INTRA RADICULAR BACTERIA OR BACTERIA FROM OUTER SIDE. ▪ Those extra radicular infections which are caused by intra radicular bacteria are treated easily by RCT. ▪Example; Sinus Tract ▪ If the extra radicular infection which are caused by outer side are treated only by Endodontic Surgery. ▪Example; Actinomycosis
  18. 18. SYMPTOMATIC INFECTIONS ▪ Occurrence and intensity of symptoms is due to interaction of following factors with each other; ▪ Difference in virulence ability among strains of same species ▪ The number of occurring species & interaction among them ▪ The number of bacterial cells (load) ▪ Environmental factors which regulate the expression of virulence factor of microbes
  19. 19. ECOLOGY OF ENDODONTIC MICROBIOTA ▪ Necrotic root canal is a fertile environment for bacterial growth. ▪ It gives bacteria a moist, warm, nutritious & anaerobic environment which is protected from host defense due to absence of microcirculation in necrotic pulp. ▪ The ecologic factors which affect the composition of microbes in necrotic root canal include; ▪ Oxygen tension & redox potential ▪ Type & amount of available nutrients ▪ Bacterial interactions
  20. 20. OXYGEN TENSION & REDOX POTENTIAL ▪ Different bacterial species dominate at different stages of the infectious process. ▪ In initial phases of pulpal infectious process; ▪ Facultative bacteria predominate ▪ During pulp necrosis & consumption by facultative bacteria, oxygen is reduced in root canal so; ▪ Obligate anaerobes predominate here
  21. 21. AVAILABLE NUTRIENTS UTILIZED BY BACTERIA IN ROOT CANAL The necrotic pulp tissue Proteins & glycol proteins from tissue fluid Components of saliva Products of metabolism of other bacteria
  22. 22. INTERACTION WITH OTHER SPECIES IN ROOT CANAL ▪Positive interaction enhances the survival capacity & quantity of interacting bacteria; ▪ Mutualism, Commensalism ▪Negative interaction decreases the quantity of bacteria; ▪ Example; Competition & Antagonism
  23. 23. APICAL PERIODONTITIS AS A BIOFILM RELATED DISEASE ▪ Bacteria in root canal may exist in one of two patterns; ▪Planktonic cells (unattached free floating cells) ▪ Easily eliminated with instrumentation & irrigation. ▪ Formation of biofilm that adheres to walls of root canal. (DOMINANT PATTERN IN APICAL PERIODONTITIS) ▪ More difficult to eradicate & require special therapeutic approaches.
  24. 24. APICAL PERIODONTITIS AS A BIOFILM RELATED DISEASE ▪ So, it means apical periodontitis is also biofilm induced oral disease like caries & marginal periodontitis. ▪ Definition of Biofilm: sessile, multicellular microbial community characterized by cells that are firmly attached to a surface and trapped in self – produce matrix. ▪ Advantages of Biofilm: ▪ Good communication among species ▪ Metabolic cooperation ▪ Protection against exogenous threats ▪ Pathogenic effect on the host