Clinical implications

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Clinical implications

  1. 1. CLINICAL IMPLICATIONS & MICROBIOLOGY OF BACTERIAL PERSISTENCE AFTER TREATMENT PROCEDURES Authors Jose F. Siqueira Jr, Ph.D, & Isabels N. Rocas, PhD JOE Vol 34, No 11, Nov 2008 PRESENTED BY Dr. Kishore Kumar .S
  2. 2. Contents Introduction Aim Discussion 1.Understanding bacterial Persistance 2.Microbiology goal of endodontic treatment 3.Persistent versus secondary infection 4.Bacterial persistence as a risk factor for posttreatment disease 5.Strategies to persist 6.When residual bacteria influence treatment outcome 7.Bacterial Taxa – persisting intracanal procedure Conclusion References
  3. 3. Introduction Microorganisms cause virtually all pathoses of the pulp and the periradicular tissues. The control of microorganisms and possible substrate must be an objective in every endodontic case. When root canal treatment fails, the cause is generally believed to be intracanal infection resisting treatment or microorganisms invading the canal via coronal leakage of root –filling. Non surgical retreatment of such cases has a modest prognosis which may indicate difficulties in the elimination of the microflora. o I.E.J.(1998) 31, 1-7 Enterococcus Faecalis is commonly found organism in failed endodontic cases.  (JOE 2004)
  4. 4. Studies have revealed that the outcome of the endodontic treatment is significantly influenced by the presence of bacteria in the root canals at the time of filling. The concept of bacteria from the root canal system should be ultimate goal of treatment of apical periodontitis. Successful treatment of both primary and secondary endodontic infection involve effective eradication of the causative microorganisms during root canal treatment procedures o OOO Vol 103, No 4, April 2007.
  5. 5. AIM This review article focuses on the microbiology and clinical implications of bacterial persistence after treatment procedures.
  6. 6. Discussion Understanding bacterial persistence Studies of bacteria occurring in the root canal after treatment involves 3 basic conditions Post instrumentation samples Post medication samples Post Obturation samples Studies investigation bacteria remaining in the root canals after chemomechanical procedures or intracanal medication serves the purpose to disclose the species that has the potential influence the treatment out come. Bacteria detected in postmedication samples survived both chemomechanical procedures or gained entry into the canal via leakage through the temporary restoration. Bacteria found in the post obturation samples of teeth indicated for retreatment
  7. 7. Microbial goals of the endodontic treatment Apical periodontitis is an infectious disease caused by microorganisms colonizing the root canal system. The endodontic treatment of the teeth containing irreversibly inflamed pulps is essentially a prophylactic treatment. On the other hand, endodontic treatment should focus not only on prevention of the introduction of new microorganisms in to the root canal system but also on the elimination of those located there in. The success rate of the endodontic treatment will depend on how effective the clinician is in accomplishing these goals .
  8. 8. Microbiological goal of endodontic treatment of teeth with apical periodontitis
  9. 9. Tissue damage caused either by the bacterial themselves or by the host defense mechanisms in response to infection. The higher the bacterial virulence the lower the number of cells necessary to cause the disease. The reachable goal is to reduce bacterial populations to a level below that necessary to induce or sustain disease.
  10. 10. Endodontic infections usually treated by using a broad spectrum non specific antimicrobial strategy. The endodontic infections can only treated by means of professional intervention using both chemical & mechanical procedures. The main step of endodontic treatment involved with control of infection represented by chemomechanical preparation & intracanal medication. Bacterial elimination from the root canal is performed by means of mechanical instruments and irrigation as well as antibacterial effects of the irrigants. Sodium hypochlorite is most widely used irrigant. Chlorhexidine has been proposed as a alternative irrigant but clinical studies showed that it is not superior to NaoCl with regards to antibacterial effectiveness.
  11. 11. Because residual bacteria can adversely effect the treatment out come , the use of inter appointment medication has been recommended to eliminate the persisting bacteria. Studies have shown that intra canal medication with a calcium hydroxide paste may be necessary to supplement the antibacterial effects chemomechanical procedures and preferably render root canals free of cultivable bacteria before filling. Entombment of bacteria in the canals by the root canal filling is one of the goals of Obturation phase.
  12. 12. Persistent versus secondary infection as the cause of failure It has not been well established whether bacteria present in the root canal – treated teeth with post- treatment disease remain from previous treatment or a consequence of reinfection. Last two decades have witnessed a marked interest on the role of secondary infection resulting of coronal leakage in treated root canals as an important cause of posttreatment apical periodontitis. However, indirect evidence seems to point to persistent infections as the most common cause of treatment failure. Should secondary infections caused by coronal leakage be the most significant cause of posttreatment disease, the failure rate for the treatment of vital teeth, necrotic teeth, n even would be similar, but they are not.
  13. 13. The bacteria present in the root canal at the time of filling procedures & materials, surviving in the changed environment, & maintaining periradicular inflammation. Bacterial persistence as a risk factor for post treatment disease Most intracanal bacteria are sensitive to standard treatment procedures. Nevertheless, some bacteria may survive treatment procedures, & their presence at the time of filling as detected by culture approaches has been recognized as a risk factor for posttreatment apical periodontitis. In a cases of treatment failure, longitudinal studies evaluating bacteria at the filling stage & retreatment
  14. 14. Microbial taxa found in the root canals filling stage and the retreatment cases o Gram positive bacteria Actinomyces naeslundi Actinomyces odontolyticus Anaerococcus prevotii Eggerthela lenta Enterococcus faecalis Gemelia morllorum Parvimonas micra Propionibacterium acnes Propionibacterium propionicum Pseudoramibacter alactolyticus Streptococcus anginosus group Streptococcus mitis
  15. 15. o Gram- negative bacteria Fuso- bacterium nucleatum Prevotella intermedia o Fungi Candida albicans Studies have shown that Enterococcus faecalis is the most commonly found species in the root canal treated teeth exhibiting emergent or persistent disease. Theoritically taxa detected at the filling stage but not at the time of retreatment may not be able to endure the conditions with in obturated canals Likewise, Taxa detected at the time of retreatment but not at the time of filling may represent secondary infection that developed by lack of a bacteria tight coronal seal.
  16. 16. Stratagies to persist For bacteria to endure treatment & be detected in post treatment samples, they must o 1.resist intracanal treatment procedures o 2. Adapt to the drastically changed environment
  17. 17. o
  18. 18. Several strategies may help bacteria to resist the treatment. Bacteria can adhere to the root canal walls, accumulate, & form communities organized in biofilms, which may be important for the bacterial resistance to & persistance after intra canal antimicrobial procedure. Antimicrobial medicaments used in endodontics can be inactivated dentin, tissue fluids, & organic matter.
  19. 19. Some micro organisms , such as E Faecalis & Candida albicans, can show resistance to calcium hydroxide, a commonly used medicament. Even though most necrotic tissue is removed during chemo mechanical procedures , remaining bacteria can also use necrotic tissue remnants as a nutrient source. Figdor et. al. reported that E.Faecalis has a ability survive in environment with scarcity of nutrients & to flourish when nutrient source is reestablished. Sedgley. et.al. showed that E.Faecalis has a capacity to recover from prolonged stravation state in root canal- treated tooth; when inoculated in to the canals, this bacterium maintained viability for 12 months without additional nutrients. Thus viable E.Faecalis entombed at the time of root canal filling may provide a long term nidus for subsequent infection.
  20. 20. When recidual bacteria influence treatment out come Bacteria that resisted intracanal procedures & are present in the canal at the filling stage can influence the outcome of the endodontic treatment provided that.. o they have the ability to withstand period of nutrient scarcity. o They resist to treatment induced disturbances in the ecology of bacterial community. o They reach relax population density. o They have unrestrained access to the periradicular tissues through perforation. o They possess virulence.
  21. 21. BACTERIAL TAXA PERSISTING IN INTRACANAL PROCEDURES Studies of effective intracanal procedures, it is advisable to identify bacterial species at the baseline and after treatment so as to rule out possible contamination during treatment, samplingor laboratory handling of sample.
  22. 22. Studies that identified bacteria persisting after intracanal disinfection procedures
  23. 23. Persistent infection ( filling stage) Single mixed infection 1-5 species per canal 100 to 100000 bacterial cells per canal Most bacteria o Streptococcus mitis o Other steptococci
  24. 24. o Fusobacterium nucleatum o provotella spp. o Pseuramibacter alactolyticus o Parvimonas micra lactobacilli Oslenllle Actinomyces spp. Persistent/ secondary infection (Retreatment cases)
  25. 25. Single mixed infection Adequate treatment: 1 to 5 species 1000 to 10000000 bacterial cells per canal 55% uncultivated bacteria Most frequent microorganisms : o Enterococcus faecalis o Candida albicans o Straptococcus species o Pseudoramibacter alactolyticus o Filifactor alocis o Diaster spp. o Actinomyces spp. o Pseudomonas aeruginosa o Enteric rods
  26. 26. Conclusion Bacteria participating in persistent infections can be identified as those present in the root canal at the time of filling, it must be recognized that many of the species found still had no sufficient time to establish a real infection and will die after filling. However those that manage to survive in the new drastically modified environment can establish a persistent infection that put the treatment outcome at risk.
  27. 27. References Endodontics : Ingle, Barkland, 5th edition Pathways of pulp : Cohen, 9th edition Endodontics : Franklin Weine, 5th edition IEJ 1998,31,1-7. IEJ 34, 399-405, 2001. OOO ,Vol103, No 4, Aprial2007. OOO Vol 1998; 85: 86-93. JOE vol33, No 7, July 2007 JOE Vol 33, No 8, Aug 2007.

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