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Dental Tribune Indian Edition

3Dental Tribune Indian Edition - January 2013 Dr Brett E Gilbert USA Root-canal treatment has been shown to have a success rate of 92%.1 How- ever, as research methodologies move towards higher levels of substantia- tion, clinicians must rely on the best current evidence available to gain insight into the expected outcomes of their treatment. The highest level and best current evidence we have on the clinical success of endodontic tre- atment comes from a meta-analysis of the literature. A meta-analysis done in 2007 by Ng et al provides a thorough review of endodontic success rates from a varie- ty of classical outcome studies. They found a weighted pooled success rate of 68 to 85%, with at least one year of follow-up.2 This review considers the strictest of criteria for determining that a tooth has healed, and includes many studies that were completed pri- or to the clinical use of dental opera- ting microscopes and other advanced armamentaria. When considering treatment for a tooth that has not healed successfully withroot-canaltherapy,therearesigni- ficant challenges to address to be able to attain complete healing of the dise- ased tooth. The armamentarium and techniques available today allow us the ability to disinfect the root-canal system properly after initial treatment has led to post-treatment disease. The success rate of retreatment has been shown to be in the range of 80% healing. Phases III and IV of the Toronto Study showed such a healing rate four to six years after non-surgical retreatment.3 In a systematic review by Torabinejad et al comparing non-surgi- cal retreatment to endodontic surgery, it was demonstrated that non-surgical retreatment had a success rate of 83% versus 71.8% for endodontic surgery after four to six years.4 The presence of pretreatment api- cal periodontitis is one factor that has been shown to decrease the success rate. Without apical periodontitis, a ten-year success rate of 92 to 98% has been shown for both initial and retre- atment root-canal therapy. With the preoperative presence of apical pe- riodontitis, there is a decrease in the success rate from 74% to 86% over the ten years.5 From this, it is evident that endodontic healing is attainable through retreatment procedures, al- lowing us to maintain our patients’ natural teeth (Figs 1a–c). Although the alternative clinical treatment op- tion of implant placement can provi- de an effective method for replacing a missing tooth, healthy maintenance of the natural tooth should remain the overall goal. Post-treatment disease is, inevita- bly, a result of bacteria and the host response of the patient to the bacteria. These microorganisms are the most critical aetiology of post-treatment disease, as they are present within the root-canal system of a previously en- dodontically treated tooth owing to a combination of substandard endodon- tic techniques, iatrogenic treatment issues and restorative failure. Intra-radicular bacteria are the primary aetiology of post-treatment disease6 and eradication of these bacteria is the primary goal of retre- atment procedures. The intra-radicu- lar bacteria present in the previously treated tooth are persistent and resist removal methods. Bacteria are able to hide and survive in canal ramifica- tions, deltas, irregularities (fins) and dentinal tubules.7 Figure 2 shows the complex root- canal anatomy preoperatively (green areas) and the minimal amount of canal-wall cleansing that was accom- plished during canal instrumentation (red areas). The remaining green are- as illustrate the space that might be left untreated, thereby providing a source of bacteria and supporting sub- strate for intra-canal infection. The potential substrates that are found inside the canal and help the bacteria survive can include untreated pulpal tissue, the presence of a biofilm and tissue fluid. This may be present in the canal owing to a poor coronal or radi- cular seal and microbial proliferation. The presence of a poor seal, bacteria and substrate for their growth results in ideal conditions for persistent in- flammation and disease.9 The bacteria present in the initial infection of a root canal differ mar- kedly from the bacteria infecting a previously treated tooth. Pretreatment flora is polymicrobial with equal num- bers of Gram-negative and -positive bacteria. Post-treatment bacteria are predominantly Gram-positive10 and they have been shown to be able to sur- vive in harsh environments and to be resistant to many treatment methods. There are high numbers of Entero- coccus species.11 Enterococcus fae- calis, for example, has been shown to be a common isolate in 27 to 77% of teeth with post-treatment disease.12 A contaminated canal space may result from incomplete cleansing initial- ly or subsequent leakage into root- canal spaces following root-canal treatment. Once present inside the canals, E. faecalis has a variety of characteristics that allow it to evade our best efforts to eradicate it from the root-canal system, including the ability to invade dentinal tubules and adhere to collagen.13 It is also resistant to calcium hydroxide application in- side the canal system, which is an inter-appointment treatment techni- que used to help remove microorga- nisms and their by-products, such as lipopolysaccharides, from the canal space.14,15 E. faecalis’s resistance of calcium hydroxide action arises from its ability to pump hydrogen ions from a proton pump. The hydrogen combi- nes with the hydroxyl ions of calcium hydroxide and neutralises the high pH value.16 E. faecalis is also able to resist calcium hydroxide by being part of a biofilm. The protection of bacteria within a biofilm matrix prevents the contact of the bacteria with irrigants and medicaments, and allows com- munication between bacteria to aid in survival capabilities.17,18 The presen- ce of E. faecalis is well documented; however, its role in post-treatment disease has yet to be proven defi- nitively.19 Its survival mechanisms, however,shinealightonthepersistent capabilities of these bacteria, and our clinical techniques must be focu- sed on the challenge of eliminating them. Iatrogenic issues encountered du- ring the initial root-canal treatment may be the cause of intra-canal bacte- rial infection. These issues may inclu- de perforation, incomplete cleansing and shaping, inadequate canal enlar- gement, missed canals, ledging, canal transportation, over-instrumentation, as well as obstruction of the canal by debris or separation of instruments. Failure to use or using too small a vo- lume of an appropriate irrigant solu- tion, such as sodium hypochlorite, is an iatrogenic error. Full-strength 6% sodium hypo- chlorite has been shown to be highly antimicrobial and able to dissolve tis- sue and disrupt bacterial biofilm.20,21 These qualities in an irrigant are ideal for the debridement of residual bacte- ria and tissue debris. The use of a rub- ber dam to isolate the treatment field is the standard of care for endodontic treatment. Failure to use a rubber dam Endodontic retreatment Achieving success the second time around Fig. 1a: Tooth #19 shows a radiolucent periapical lesion around the mesial root apex and into the furcation.—Fig. 1b: Post-op radio- graph.—Fig. 1c: One-year follow-up radiograph. (Courtesy of Dr Brett E. Gilbert)—Fig. 2: The unprepared pulpal tissue (green) and the post-op prepared or instrumented areas (red), showing the complexity of the root-canal anatomy and the difficulty in completely cleansing the root-canal system. (Courtesy of rootcanalanatomy.blogspot.com) Fig 1a Fig 2Fig 1c Fig 1b Trends & Applications Published by Jaypee Brothers Medical Publishers (P) Ltd., India © 2013, Dental Tribune International GmbH. All rights reserved. Dental Tribune India makes every effort to report clinical information and manufacturer’s product news accurately, but cannot assume responsibility for the validity of product claims, or for typographical errors. The publishers also do not assume responsibility for product names or claims, or statements made by advertisers. Opinions expressed by authors are their own and may not reflect those of Dental Tribune International. Chairman DT India Jitendar P Vij jaypee@jaypeebrothers.com Director P N Venkatraman venkatraman@jaypeebrothers.com Dental Tribune India Published by: Jaypee Brothers Medical Publishers (P) Ltd. 4838/24, Ansari Road, Daryaganj New Delhi 110002, India Phone: +91 11 43574357 e-mail:jaypee@jaypeebrothers.com Website: www.jaypeebrothers.com Dental TribuneIndia Edition International Imprint Licensing by Dental Tribune International Publisher Torsten Oemus Group Editor Daniel Zimmermann newsroom@dental-tribune.com +49 341 48 474 107 Clinical Editor Magda Wojtkiewicz Online Editor Yvonne Bachmann Editorial Assistant Claudia Duschek Copy Editors Sabrina Raaff Hans Motschmann Publisher/President/CEO Torsten Oemus Director of Finance & Controlling Dan Wunderlich Media Sales Managers Matthias Diessner Peter Witteczek Maria Kaiser Melissa Brown Vera Baptist Marketing & Sales Services Esther Wodarski License Inquiries Jörg Warschat Accounting Karen Hamatschek Business Development Manager Bernhard Moldenhauer Executive Producer Gernot Meyer International Editorial Board Dr Nasser Barghi, USA – Ceramics Dr Karl Behr, Germany – Endodontics Dr George Freedman, Canada – Aesthetics Dr Howard Glazer, USA – Cariology Prof Dr I. Krejci, Switzerland – Conservative Dentistry Dr Edward Lynch, Ireland – Restorative Dr Ziv Mazor, Israel – Implantology Prof Dr Georg Meyer, Germany – Restorative Prof Dr Rudolph Slavicek, Austria – Function Dr Marius Steigmann, Germany – Implantology © 2013, Dental Tribune International GmbH. All rights reserved. Dental Tribune makes every effort to report clinical information and manufacturer’s product news accurately, but cannot assume responsibility for the validity of product claims, or for typographical errors. The publishers also do not assume responsibility for product names or claims, or statements made by advertisers. Opinions expressed by authors are their own and may not reflect those of Dental Tribune International. 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