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10 Dental Tribune Middle East & Africa Edition | September-October 2015mcme Endodontic irrigants and irrigant delivery systems mCME articles in Dental Tribune have been approved by: HAAD as having educational content for 2 CME Credit Hours DHA awarded this program for 2 CPD Credit Points CAPPmea designates this activity for2continuingeducationcredits. By Gary Glassman, Canada E ndodontic treatment is a predictable procedure with high success rates. Success depends on a number of factors, including appropri- ate instrumentation, successful irrigation and decontamination of the root-canal space to the apices and in areas such as isth- muses. These steps must be fol- lowed by complete obturation of the root canals, and place- ment of a coronal seal, prior to restorative treatment. Several irrigants and irrigant delivery systems are available, all of which behave differently and have relative advantages and disadvantages. Common root-canal irrigants include sodium hypochlorite (NaOCl), chlorhexidine gluconate, al- cohol, hydrogen peroxide and ethylenediaminetetraacetic acid (EDTA). In selecting an irrigant and technique, consid- eration must be given to their efficacy and safety. With the introduction of mod- ern techniques, success rates of up to 98 percent are being achieved.1 The ultimate goal of endodontic treatment per se is the prevention or treatment of apical periodontitis, such that there is complete healing and an absence of infection,2 while the overall long-term goal is the placement of a definitive, clini- cally successful restoration and preservation of the tooth. For these to be achieved, appropri- ate instrumentation, irrigation, decontamination and root-ca- nal obturation must occur, as well as attainment of a coronal seal. There is evidence that apical periodontitis is a biofilm-in- duced disease.3 A biofilm is an aggregate of microorganisms in which cells adhere to each other and/or to a surface. These adherent cells are frequently embedded within a self-pro- duced matrix of extracellular polymeric substance. The pres- ence of microorganisms em- bedded in a biofilm and grow- ing in the root-canal system is a key factor for the development of periapical lesions.4–7 Addi- tionally, the root-canal system has a complex anatomy that consists of arborisations, isth- muses and cul-de-sacs that har- bor organic tissue and bacterial contaminants (Figs. 1a, b).8 The challenge for successful endodontic treatment has al- ways been the removal of vital and necrotic remnants of pulp tissue, debris generated dur- ing instrumentation, the dentin smear layer, microorganisms, and micro-toxins from the root- canal system.9 Even with the use of rotary in- strumentation, the nickel-titani- um instruments currently avail- able only act on the central body of the root canal, resulting in a reliance on irrigation to clean beyond what may be achieved by these instruments.10 In ad- dition, Enterococcus faecalis and Actinomyces prevention or treatment of apical periodonti- tis such as Actinomyces israelii — which are both implicated in endodontic infections and in endodontic failure — penetrate deep into dentinal tubules, making their removal through mechanical instrumentation impossible.11,12 Finally, E. faeca- lis commonly expresses multid- rug resistance,13–15 complicating treatment. Therefore, a suitable irrigant and irrigant delivery system are essential for efficient irrigation and the success of endodontic treatment.16 Root-canal irri- gants must not only be effective for dissolution of the organic of the dental pulp, but also ef- fectively eliminate bacterial contamination and remove the smear layer — the organic and inorganic layer that is created on the wall of the root canal during instrumentation. The ability to deliver irrigants to the root-canal terminus in a safe manner without causing harm to the patient is as important as the efficacy of those irrigants. Over the years, many irrigating agents have been tried in order to achieve tissue dissolution and bacterial decontamination. The desired attributes of a root- canal irrigant include the ability to dissolve necrotic and pulpal tissue, bacterial decontamina- tion and a broad antimicrobial spectrum, the ability to enter deep into the dentinal tubules, biocompatibility and lack of toxicity, the ability to dissolve inorganic material and remove the smear layer, ease of use, and moderate cost. As mentioned above, root-ca- nal irrigants currently in use include hydrogen peroxide, NaOCl, EDTA, alcohol and chlorhexidine gluconate. Chlo- rhexidine gluconate offers a wide antimicrobial spectrum, the main bacteria associated with endodontic infections (E. faecalis and A. israelii) are sen- sitive to it, and it is biocompat- ible, with no tissue toxicity to the periapical or surrounding tissue.17 Chlorhexidine gluco- nate, however, lacks the abil- ity to dissolve necrotic tissue, which limits its usefulness. Hy- drogen peroxide as a canal irri- gant helps to remove debris by the physical act of irrigation, as well as through effervescing of the solution. However, while an effective anti-bacterial irrigant, hydrogen peroxide does not dissolve necrotic intra-canal tis- sue and exhibits toxicity to the surrounding tissue. Cases of tissue damage and fa- cial nerve damage have been reported following use of hy- drogen peroxide as a root-canal irrigant.18 Alcohol-based canal irrigants have antimicrobial activity too, but they do not dis- solve necrotic tissue. The irrigant that satisfies most of the requirements for a root- canal irrigant is NaOCl.19,20 It has the unique ability to dis- solve necrotic tissue and the or- ganic components of the smear layer.19,21,22 It also kills sessile endodontic pathogens organ- ized in a biofilm.23,24 There is no other root-canal irrigant that can meet all these require- ments, even with the use of methods such as lowering the pH,25–27 increasing the tempera- ture28–32 or adding surfactants to increase the wetting efficacy of the irrigant.33,34 However, al- though NaOCl appears to be the most desirable single endodon- tic irrigant, it cannot dissolve inorganic dentine particles and thus cannot prevent the forma- tion of a smear layer during in- strumentation.35 Calcifications hindering me- chanical preparation are fre- quently encountered in the root-canal system, further com- plicating treatment. Demineral- izing agents such as EDTA have therefore been recommended as adjuvants in root-canal therapy.20,36 Thus, in contempo- rary endodontic practice, dual irrigants such as NaOCl with EDTA are often used as initial and final rinses to circumvent the shortcomings of a single ir- rigant.37–39 These irrigants must be brought into direct contact with the entire canal-wall sur- faces for effective action,20,37,40 particularly in the apical por- tions of small root canals.9 The combination of NaOCl and EDTA has been used world- wide for antisepsis of root-canal systems. The concentration of NaOCl used for root-canal irri- gation ranges from 2.5 to 6 per- cent, depending on the country and local regulations; it has been shown, however, that tis- sue hydrolyzation is greater at the higher end of this range, as demonstrated in a study by Hand et al. comparing 2.5 and 5.25 percent NaOCl. The higher concentration may also favor superior microbial outcomes.41 NaOCl has a broad antimicrobial spectrum,20 in- cluding but not limited to E. faecalis. NaOCl is superior among irrigating agents that dissolve organic matter. EDTA is a chelating agent that aids in smear layer removal and increases dentine permeabil- ity,42,43 which will allow further irrigation with NaOCl to pen- etrate deep into the dentinal tubules.44 General safety precautions Regardless of which irrigant and irrigation system is em- ployed, and particularly if an irrigant with tissue toxicity is used, there are several general precautions that must be fol- lowed. A rubber dam must be used and a good seal obtained to ensure that no irrigant can spill from the pulp chamber into the oral cavity. If deep caries or a fracture is present adjacent to the rubber dam on the tooth be- ing isolated, a temporary seal- ing material must be used prior to performing the procedure to ensure a good rubber dam seal. It is also important to protect the patient’s eyes with safety glasses and protect clothing from irrigant splatter or spill. It is very important to note that while NaOCl has unique prop- erties that satisfy most require- ments for a root-canal irrigant, it also exhibits tissue toxicity that can result in damage to the adjacent tissue, including nerve damage should NaOCl inci- dents occur during canal irri- gation. Furthermore, Salzgeber reported in the 1970s that api- cal extrusion of an endodontic irrigant routinely occurred in vivo.45 This highlights the im- portance of using devices and techniques that minimize or prevent this. NaOCl incidents are discussed later in this arti- cle. Irrigant delivery systems Root-canal irrigation systems can be divided into two cat- egories: manual agitation techniques and machine-as- sisted agitation techniques.9 Manual irrigation includes positive-pressure irrigation, which is commonly performed with a syringe and a sidevented needle. Machine-assisted ir- rigation techniques include sonics and ultrasonics, as well as newer systems such as the EndoVac (Kerr Endodontics, Orange, CA), which delivers apical negative-pressure irriga- tion,46 the plastic rotary F File (Plastic Endo),47,48 the Vibringe (Vibringe),49 the Rinsendo (Air mCME SELF INSTRUCTION PROGRAM CAPPmea together with Dental Tribune provides the opportunity with its mCME - Self Instruction Program a quick and simple way to meet your continuing education needs. mCME offers you the flexibility to work at your own pace through the material from any location at any time. The content is international, drawn from the upper echelon of dental medicine, but also presents a regional outlook in terms of perspective and subject matter. Membership: Yearly membership subscription for mCME: 900 AED One Time article newspaper subscription: 250 AED per issue. After the payment, you will receive your membership number and Allowing you to start the program. 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