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23Implant TribuneMay 17-23, 2010United Kingdom Edition however, the protocols used to- day cannot predictably provide sterile canals. As none of the elements of endodontic therapy (host defense system, systemic antibiotic therapy, instrumen- tation and irrigation, inter- appointment medicaments, per- manent root filling, and coro- nal restoration) can alone guar- antee complete disinfection, it is of utmost importance to aim at the highest possible qual- ity at every phase of the treat- ment. In the classic study by Sjogren et al, 55 single-rooted teeth with apical periodontitis were instrumented and irrigated with sodium hypochlorite and root filled. Periapical healing was followed-up for five years. Complete periapical healing occurred in 94 per cent of cases that yielded a negative cult- ure. Where the samples were positive prior to root filling, the success rate of treatment was just 68 per cent – a statistically significant difference. These findings emphasise the impor- tance of completely eliminat- ing bacteria from the root canal system prior to obturation. This objective cannot be reliably achieved in a one-visit treatment of necrotic pulps because it is not possible to eradicate all infection from the root canal without the support of an inter-appointment antimicrobial dressing (25) . NaOCl is the most widely used irrigating solution. It is a potent antimicrobial agent and lubricant, which effectively dis- solves pulpal remnants and or- ganic components of dentin thus preventing packing infected hard and soft tissue into the apical con- fines. Hypochlorous acid (HClO) is the active moiety responsible for bacterial inactivation. NaOCl is used in concentrations vary- ing from 0.5 per centto 5.25 per cent; the in vitro and in vivo stud- ies differ significantly in terms of the effectiveness of the range of concentrations as the in vitro experiments provide direct ac- cess to microbes, higher volumes are used and the chemical milieu complexity of the natural canal space are absent than in the in vivo experimentation. A study by Siqueira et al (26) showed no dif- ference (in vitro) between one per cent, 2.5 per cent and give per cent NaOCl solutions in reducing the number of bacteria during instrumentation. What has been shown is that the tissue dissolv- ing effects are directly related to the concentration used (27) . Perhaps the most misunder- stood aspect of NaOCl irrigation is the need for the quantities of irrigation required due to the morphologic and anatomic vari- ations in the volumetric sise of the root canal anatomy. Siqueira showed that regular exchange and the use of large amounts of irrigant should maintain the antibacterial effectiveness of the NaOCl solution, compensating for the effects of concentration (28) . Numerous devices have ap- peared in the endodontic arma- mentarium to address this situ- ation; EndoVac (Discus Dental) – a negative pressure differen- tial device designed to deliver high volumes of irr-igation so- lution while using apical nega- tive pressure through the office high volume evacuation system, Negative Pressure Safety Irriga- tor (Vista Dental, Racine WI) – device is similar to EndoVac, Rinsendo (Air Techniques, Co- rona CA) uses pressure suction technology; 65ml of irrigant are automatically drawn from the attached syringe and aspirated into the canal (pressure created is lower than manual irrigation), VIbringe (Bisco Canada, Rich- mond BC) – sonic flow technolo- gy facilitates enhanced irrigation through the myriad complexities of the root canal system (Fig 11). NaOCl cannot dissolve in- organic dentin particles and thus prevent smear layer for- mation during instrumentation (29) . Chelators such as EDTA and citric acid are recommended as adjuvants in root canal ther- apy. It is probable that biofilms are detached with the use of che- lators; however, they have lit- tle if any antibacterial activity. Several studies have shown that citric acid in concentrations ranging as high as 50 per cent was more effective at solubili- sation of inorganic smear layer components and powdered den- tin than EDTA. In addition, citric acid has demonstrated antibacte- rial effectiveness. Technology and innovation will not negate the need for op- timal preparation (debridement and disinfection) to eliminate microbial content and its impact on a necrotic root canal system. We as a discipline need to be bet- ter; however, by the same token, endodontics has shown its com- mitment to endless reinvention. In time, that will restructure the role of natural teeth in founda- tional dentistry, currently di- minished by the market forces of implant driven dentistry. Or- thobiologic replacement is not a panacea as random clinical trials increasingly show; the se- verity of peri-implantitis lesions demonstrates significant vari- ability and as such no treatment modality has shown superiority. The pendulum will continue to swing as the endodontic implant algorithm becomes increasingly multivariate. DT Part 2 in next issue, including references About the author Kenneth S Serota, DDS, MMSc graduated from the University of To- ronto, Faculty of Den- tistry in 1973 and was awarded the George W Switzer Memorial Key for excellence in Prosthodontics. He received his Certificate in Endodontics and Master of Medical Sciences Degree from the Harvard-Forsyth Dental Cent- er in Boston, MA. A recipient of the recipient of the American Association of Endodontics Memorial Research Award for his work in nuclear medi- cine screening procedures related to dental pathology, his passion is educa- tion and most recently e-learning and rich media. He was selected for Fel- lowship in the Pierre Fauchard Acad- emy and is a Fellow of the Academy of Dentistry International. The author of more than sixty publications, he has lectured on Endodontics internation- ally. He is on the editorial board of En- dodontic Practice, Endodontic Tribune and Implant Tribune. The founder of ROOTS – an online educational forum for dentists from around the world who wish to learn cutting edge endo- dontic therapy, he recently launched IMPLANTS (www.rximplants.com) and www.tdsonline.org in order to provide a clear understanding of the endodontic/implant algorithm in foun- dational dentistry. As well, he lectures on the empowerment digital technolo- gies provide to the sophistication of the dental team and the propagation of comprehensive care. Fig 10 – A vast array of equipment exists in the marketplace to optimize irrigation protocols. Radical change may well be in the offing, however, R&D on bio-active obturating materials may prove to be the defining variable in total asepsis. Fig 11 – Numerous investigators have shown that the concept of keeping the apical foramen foramen as small as practical does not mean a size 20 or 25 file. This Schilderian concept should read as small as the apical morphology permits in order to ensure that the free flow of irrigant to the apical terminus enables more definitive cleaning of the apical segment of the root canal space. Table I and II – derived from Antibiotics and the Treatment of Endodontic Infections – Summer 2006 – American Association of Endodontics – Colleagues for Excellence