ENDODONTIC MICROBIOLOGY types of bacteria powerpoint

endodontic microbiology powerpoint

1. ENDODONTIC
MICROBIOLOGY
DR SONAL BANSAL

2. INTRODUCTION
•Most of the pathologies of pulp and periapical
tissues are directly or indirectly related to the
microorganisms
•Endodontic infections is the infection of the
root canal system and is the major etiological
factor of apical periodontitis
•The root canal infection usually develops
after pulpal necrosis, which can occur as a
sequel to caries, trauma and periodontal
diseases or operative procedures

3. HISTORY
•In 17
th
century Leeuwenhoek was first to describe
the oral microflora
•Later on in 1890, it was W.D Miller Father of
oral microbiology authorized a book
“microorganisms of human mouth”
•Then in 1904, F.Billings described the theory of
focal infections as a circumscribed area of tissue
with pathognomic microorganisms
•In 1909 EC Rosenow described the theory of
focal infections as localised or generalised
infections caused by bacteria travelling through
the blood stream from a distinct focus of infection

4. •Then later on in 1939 Fish described 4 zones of
infection:
•1) Zone of Infection – Bacteria get confined by
PMNs.
•2) Zone of Contamination – Inflammatory cells
mostly but no bacteria
•3) Zone of Irritation – Histiocytes and Osteoclasts
and small amount of repair is seen
•4) Zone of Stimulation – Fibroblast and osteoblast
seen, new bone formed in irregular fashion

5. •Fish stated that removal of this nidus of
infection would lead to resolution of
infection. (This became the basis of
successful endodontic therapy)
•1965 - Kakeshi et al Significance of
Bacteria in pulpal disease.

6. Portals of entry for microorganisms
•ROUTES OF MICROBIAL INGRESS TO
THE PULP:
•Through the open cavity.
•Through the dentinal tubules.
•Through the gingival sulcus or PDL.
•Through the bloodstream
•Broken / Faulty / Seal / Restoration
•Through extension of a periapical infection
from adjacent infected teeth.

7. Endodontic Microflora
•With time it has become clear that endodontic flora consists
primarily of anaerobes. This has been inferred from newly
developed culturing techniques which are able to culture
anaerobes. Most of the bacteria are now known to be strict
anaerobes. They grow in the absence of oxygen but vary in
their sensitivity to oxygen:
•Some function at low oxidation reduction potential and
generally lack the enzymes superoxide dismutase and
catalase – Strict anaerobes.
•Some bacteria grow in the presence or absence of oxygen –
Facultative anaerobes. They have the enzymes superoxide
dismutase and catalase.
• Some grow only in the absence of oxygen – Obligate
anaerobes.
 

8. Classification of bacterial genera
prevalent in endodontic infections
Anaerobic gram-negetive baacteria:
a)Prophyromonas
b)Fusobacterium
c)Prevotella
d)Veillonella
Facultative gram negetive bacteria
a)Neisseria
b)Haemophilus
c)Capnocytophaga
Anaerobic gram positive bacteria
a)Actinomyces
b)Eubacterium
c)Peptostreptococcus
Facultative gram positive bacteria
a)Streptococcus
b)Lactobacillus
c)Enterococcus

9. Microbial ecosystem of the root
canal
•Various papers have been published
regarding the microbial flora of the root
canals
•Over past few years(5-10 years)
difference in the flora has been reported
due because of improoved technology in
sampling and culturing techniques

10. •Most commonly gram positive organisms are
found in the root canals but gram negative and
obligate anaerobes have also been found in the
root canal
•Usually the microorganisms which can survive in
low oxygen supply can survive in the root canal
•In necrotic pulp a mix of bacterial species is found
•In necrotic pulp as there is lack of circulation with
compromised defense mechanism this makes it
more prone to infection

11. •In necrotic pulp, tissue fluids and
disintegrated cells, low oxygen tension and
bacterial interaction are main factors which
will decide which bacteria will predominate
•As the growth of one bacterial species may
be dependent on the other bacterial
species which supplies the essential
nutrients

12. BACTERIA IN PERIAPICAL TISSUE
•Earlier beliefs were that bacteria remained
housed in the dental root canal system i.e.
the main canals, lateral canals and dentinal
canals. Studies now have indicated that in
chronic lesions, the host defense can
effectively inhibit bacterial invasion and
spread of infection by production of a fibrotic
demarcation zone. Only in acute stages of
exacerbation and formation of an acute
abscess, can microbes invade periapical
tissue.

13. PRESENCE OF A SINUS INDICATES A
PERMANENT PRESENCE OF BACTERIA OF
BACTERIA IN PERI RADICULAR TISSUE
•Since after chemo mechanical
debridement, the fistulas and sinus close
down, the cause bacterial survival in the
extra radicular area is dependent on the
depot of infection in the root canal.

14. BACTERIA ASSOCIATED WITH
INSTRUMENTATION AND BACTEREMIA
•Instrumentation eliminates bacteria from root canal and but
may induce a transient bacteremia.
• Periapically bacteria may reach the region due to:
- growing and advancing bacteria from the roots can now
- Seeding of bacteria periapically due to over-instrumentation or
trauma
 
- But maximum cases of bacteria are seen in connection with
trauma, extraction and scaling procedures.
 
•Species recovered after over-instrumentation are
fusaobacterium, Prevotella Intermedia, peptostreptococcus,
propionibacteria, actinomyces, streptococcus
•Gradually the bacteria overcome this and more of a gram
positive species are found [propionibacteria and actinomyces]
that this after about ten to fifteen minutes from instrumentation.

15. Types of endodontic infections
•Endodontic infections are classified
according to their anatomical location that is
intraradicular and extraradicular infections
•Intraradicular infections are characterized by
the presence of microorganisms within the
root canal system
•They are further classified as
•Primary
•Secondary
•Persistent

16. •Primary intraradicular infections caused by
microorganisms that initially invade and colonize
necrotic pulp tissue
Characterized by mixed consortium dominated by
anaerobic bacteria , particularly gram negative like
prophyromonas, prevotella, fusobacterium,
campylobactor and gram positive genera
peptostreptococcus, eubacterium, actinomyces
In prevotella especially prevotella intermedia is
commonly found in primary endodontic infections.

17. •Secondary intraradicular infection
•Are introduced during treatment between
appointments or after the treatment
• Psudomonas and Staphylococcus species,
E.coli, candida sp and E.faecalis are
commonly found in such infections
•Can penetrate even after the completion of
root fillings
•These infections are characterized by the
organisms that were not prevalent during
primary infection

18. •Persistant intraradicular infections
•Caused by the microorganisms that
resisted the intracanal antimicrobial
procedures
•Higher frequencies of fungi are present
than in primary infections
•E.faecalis is predominant in such cases

19. •E.faecalis is the persistant organism that
despite making up a small proportion of the
flora in the root canal space plays a major
role in causing persistant periradicular
lesions after the treatment
•Able to survive as a single organism or as a
major component in the flora
•Commonly associated with asymptomatic
cases than symptomatic

20. •Persistent and secondary infections are
responsible for persistent exudation,
persistent symptoms, intraappointment
exacerbations, and faliure of endodontic
treatment characterized by persistent
apical periodontitis.

21. Persistent/Secondary
Endodontic Infections
•Persistent or secondary intraradicular infections are
the major causes of endodontic treatment failure
•This statement is supported by two strong evidence-
•First, it has been demonstrated that there is an
increased risk of adverse treatment outcome when
bacteria are present in the canal at the time of filling.
•Second, most (if not all) root canal–treated teeth
evincing persistent apical periodontitis lesions have
been demonstrated to harbor an intraradicular
infection.

22. Bacteria at the Root Canal–
Filling Stage
•Effective antimicrobial treatment may still fail to completely
eliminate bacteria from the infected root canal system. This is
because persisting bacteria are either resistant or inaccessible to
treatment procedures.
•Gram-negative bacteria, which are common members of primary
infections, are usually eliminated. Exceptions include some
anaerobic rods, such as F. nucleatum, Prevotella species, and
Campylobacter rectus, which are among the species found in post
instrumentation or post medication samples.
• Most studies have revealed that when bacteria resist treatment
procedures, gram-positive bacteria are more frequently present.
• Gram-positive facultatives or anaerobes often detected in these
samples include streptococci, Actinomyces species,
Propionibacterium species, lactobacilli, E. faecalis

23. •This gives support that gram-positive
bacteria can be more resistant to
antimicrobial treatment measures and have
the ability to adapt to the harsh environmental
conditions in instrumented and medicated
root canals.
•Bacteria persisting in the root canal after
chemomechanical procedures or intracanal
medication will not always maintain an
infectious process.

24. •This statement is supported by evidence that some
apical periodontitis lesions healed even after bacteria
were found in the canal at the filling stage and the
evidence supporting it are:
Residual bacteria may die after filling because of toxic
effects of the filling material, access denied to
nutrients, or disruption of bacterial ecology
 Residual bacteria may be present in quantities and
virulence subcritical to sustaining periradicular
inflammation.
• Residual bacteria remain in locations where access
to periradicular tissues is denied.

25. •Bacteria that resist intracanal procedures and are present in the canal at the time of
filling can influence the outcome of the endodontic treatment by:
 Have the ability to withstand periods of nutrient scarcity, scavenging for low traces of
nutrients and/or assuming a dormant state or a state of low metabolic activity, to
prosper again when the nutrient source is reestablished
 Resist treatment-induced disturbances in the ecology of the bacterial community
Reach a critical population density (load) necessary to inflict damage to the host
 Have unrestrained access to the periradicular tissues through apical/lateral foramina
or iatrogenic root perforations
 Possess virulence attributes that are expressed in the modified environment and
reach concentrations adequate to directly or indirectly induce damage to the
periradicular tissues

26. Microbiota in Root Canal–
Treated Teeth
•Several culture and molecular biology studies have revealed that E. faecalis
is the most frequent species in root canal–treated teeth, with prevalence
values reaching up to 90% of cases root canal–treated teeth are about nine
times more likely to harbor E. faecalis than cases of primary infections
•The fact that E. faecalis has been commonly recovered from cases treated
in multiple visits and/or in teeth left open for drainage

suggests that this
species may be a secondary invader that succeeds in colonizing the canal,
resists treatment, and causes a secondary infection that then becomes
persistent.
•The ability of E. faecalis to penetrate dentinal tubules, sometimes to a deep
extent

, can enable it to escape the action of endodontic instruments and
irrigants used during chemomechanical preparation.
• Moreover, its ability to form biofilms in root canals can be important for its
resistance to and persistence after intracanal antimicrobial procedures
•Enterococcus faecalis is also resistant to calcium hydroxide

27. •Other bacteria found in root canal–treated teeth with
apical periodontitis include streptococci ,anaerobic
bacterial species:, Propionibacterium propionicum,
Filifactor alocis, Dialister pneumosintes, Prevotella
intermedia, and Treponema denticola
•Fungi are only occasionally found in primary
infections, but Candida species have been detected in
root canal–treated teeth in up to 18% of the cases.
•Candida albicans is by far the most commonly
detected fungal species in root canal–treated teeth.
This species has several properties that can be
involved in persistence following treatment, including
its ability to colonize and invade dentin and resistance
to calcium hydroxide.

28. Extraradicular Infections
•Apical periodontitis lesions are formed in response to
intraradicular infection.
•The most common form of extraradicular infection is the acute
apical abscess, characterized by purulent inflammation in the
periradicular tissues in response to a massive egress of
virulent bacteria from the root canal. There is, however,
another form of extraradicular infection which, unlike the acute
abscess, is usually characterized by absence of overt
symptoms.
•This condition entails the establishment of microorganisms in
the periradicular tissues, either by adherence to the apical
external root surface in the form of biofilm structures

or by
formation of cohesive actinomycotic colonies within the body
of the inflammatory lesion.

29. •Situations permit intraradicular bacteria to reach the periradicular
tissues and establish an extraradicular infection are:
A result of direct advance of some bacterial species that overcome
host defenses concentrated near or beyond the apical foramen, an
extension of the intraradicular infectious process
Due to bacterial persistence in the apical periodontitis lesion after
remission of acute apical abscesses. The acute apical abscess is
for the most part clearly dependent on the intraradicular infection;
once the intraradicular infection is properly controlled by root canal
treatment or tooth extraction and drainage of pus is achieved, the
extraradicular infection is handled by the host defenses and usually
subsides.
A sequel to apical extrusion of debris during root cana
instrumentation (particularly after overinstrumentation).

30. Biofilms
•It is defined as a community of microorganisms of one or
more species that are embedded in an extracellular
polysaachride matrix and are attached to solid surface
•According to cardwell et al a biofilm has following attributes:
•Autopoiesis – ability to self organise
•Homeostasis – ability to resist envoirmental disturbances
•Synergy – effective in association with fellow microorganisms
than in isolation
•Communality – respond to envoirmental challenges as a
combined unit
•They are significant as they are responsible for the
endodontic failure

31. •Endodontic biofilm can be classified into:
•Intracanal microbial biofilms – these are formed on
the radicular dentin in an endodontically infected tooth.
Various types of bacteria can develop these biofilms , but
E.faecalis is responsible for its formation
Extraradicular microbial biofilms – these are formed
on the cemental surface around the root apex of an
endodontically infected tooth
Periapical microbial biofilms – these are isolated
biofilms which are independent of the internal or
external surface of the root canal .
Actinomyces sp have been shown to form periapical
leisons resistant to endodontic therepy

32. Culture of microorganisms
•Traditional means of examining the endodontic microbiota
•It is the cultivation and propagation of microorganisms in
artificial and favourable laboratory conditions
•Grossman has shown that a single organism of certain species
of oral microorganisms is sufficient to initiate growth in the
cultural medium
•Several media are used for culturing material from root canals
such as brain heart infusion broth with .1% agar, trypticase soy
broth with .1% agar, thioglycolate , and glucose ascites broth.
•Moller investigated the influence of water quality , various salts
, organic material , reducing agents of obtaining oxygen free
envoirment
•

33. Clinical relevance
•Currently available cultural media and
techniques used to grow root canal
microorganisms may not be perfect when
compared with newer molecular biological
methods
•Yet they remain as a valuable tool that guide
the and improve the understanding of the
pathogenesis of diseases
•This technique is time consuming and
laborious.

34. Molecular biology methods
•They are based on the identification of
specific biological markers present in the
genes of the microorganisms that aid in
the identification of the microorganisms
•Among the various methods available

• polymerase chain reaction are very
accurate methods

35. •PCR methodology is atleast 10-100 times
more sensitive than other more sensitive
identification methods
•The most commonly employed PCR assay
as follows:
•Nested
•Reverse transcriptase
•Real time
•Touch down

36. Conclusion
•FORMULA FOR SUCCES:
•Debridement
•Antibacterial irrigation
•Judicious use of intracanal medication and
oxygenating agents
•Selection of an appropriate broad spectrum
antibiotic
•Three dimensional obturation of the root
canal system

37. •The apparent presence of microorganism
does not ensure endodontic failure nor does
the apparent absence of microbes guarantee
success.
• However, the presence of microbes
particularly those of certain types, provides
an additional source of irritation that the body
must overcome to gain results.
•Therefore, the control of microbes and
possible substrate must be an objective in
every endodontic case.