Please activate JavaScript!
Please install Adobe Flash Player, click here for download

Dental Tribune Middle East & Africa Edition No. 5, 2015

12 Dental Tribune Middle East & Africa Edition | September-October 2015mCME < Page 11 with a 0.02 taper and is attached to a handpiece for gross, initial flushing of the coronal and mid- length parts of the root canal. The MicroCannula contains 12 microscopic holes and is capa- ble of evacuating debris to full working length.102 The ISO size 0.32 mm diameter stainless-steel MicroCannula has four sets of three laser-cut, laterally positioned offset holes adjacent to its closed end, 100 μ in diameter and spaced 100 μ apart. This is attached to a fin- ger piece for irrigation of the apical part of the canal when it is positioned at working length. The MicroCannula can be used in canals that are enlarged with endodontic files to ISO size 35.04 or larger. During irrigation, the Master Delivery Tip delivers irrigant to the pulp chamber and siphons off the excess irrigant to pre- vent overflow. Both the Mac- roCannula and MicroCannula exert negative pressure that pulls fresh irrigant from the chamber, down the canal to the tip of the cannula, into the can- nula, and out through the suc- tion hose. Thus, a constant flow of fresh irrigant is delivered by negative pressure to working length. A recent study showed that the volume of irrigant de- livered was significantly higher than the volume delivered by conventional syringe needle irrigation within the same pe- riod,46 and resulted in signifi- cantly more debris removal at 1 mm from working length than did needle irrigation. During conventional root-ca- nal irrigation, clinicians must be careful when determining how far an irrigation needle is placed into the canal. Rec- ommendations for avoiding NaOCl incidents include not binding the needle in the canal, not placing the needle close to working length, and using a gentle flow rate when using positive-pressure irrigation.103 With the EndoVac, in contrast, irrigant is pulled into the canal at working length and removed by negative pressure. Apical negative pressure has been shown to enable irrigants to reach the apical third and help overcome apical vapor lock.46,104 In addition, with respect to isth- mus cleaning, although it is not possible to reach and clean the isthmus area with instruments, it is not impossible to reach and thoroughly clean these areas with NaOCl when the method of irrigation is safe and effica- cious. In studies comparing the EndoActivator,105 passive ultrasonic,105 the F File,105 the manual-dynamic Max-i-Probe (DENTSPLY Rinn),105,106 the Pressure Ultrasonic111 and the EndoVac,106 only the EndoVac was capable of cleaning 100 percent of the isthmus area. Apart from being able to avoid air entrapment, the EndoVac system is also advantageous in its ability to deliver irrigants safely to working length without causing their undue extrusion into the periapex,46,102 thereby avoiding NaOCl incidents. It is important to note that it is pos- sible to create positive pressure in the pulp canal if the Master Delivery Tip is misused, which would create the risk of a NaO- Cl incident. The manufacturer’s instructions must be followed for correct use of the Master Delivery Tip. Sodium hypochlorite inci- dents Although a devastating en- dodontic NaOCl incident is rare,107 the cytotoxic effects of NaOCl on vital tissue are well established.108 The associated sequelae of NaOCl extrusion have been reported to include life-threatening airway obstruc- tions,109 facial disfigurement re- quiring multiple corrective sur- gical procedures,110 permanent paraesthesia with loss of facial muscle control,69 and — the least significant consequence — tooth loss.111 Although the exact etiology of the NaOCl incident is still un- certain, based on the evidence from actual incidents and the location of the associated tissue trauma, it would appear that an intravenous injection may be the cause. The patient shown in Figure 3 demonstrates a widespread area of tissue trau- ma that is onsistent with the characteristics of NaOCl inci- dent trauma reported by Pash- ley.108,112 This extensive trauma, and par- ticularly involving the pattern of ecchymosis around the eye, could have occurred only if the NaOCl had been introduced in- travenously to a vein close to the root apex through which extru- sion of the irrigant occurred and the irrigant then found its way into the venous complex. This would require positive pressure apically that exceeded venous pressure (10mg of Hg). In one in-vitro study, which used a positive-pressure needle irriga- tion technique to mimic clinical conditions and techniques, the apical pressure generated was found to be eight times higher than the normal venous pres- sure.113 This does not imply that NaOCl can or should be excluded as an endodontic irrigant; in fact, its use is critical, as has been dis- cussed in this article. What this does imply is that it must be de- livered safely. Safety first In order to compare the safety of six current intra-canal irriga- tion delivery devices, an in-vitro test was conducted using the worst-case scenario of apical extrusion, with neutral atmos- pheric pressure and an open apex.102 The study concluded that the EndoVac did not ex- trude irrigant after deep intra- canal delivery and suctioning of the irrigant from the chamber to full working length, whereas other devices did. The Endo- Activator extruded only a very small volume of irrigant, the clinical significance of which is not known. Mitchell and Baumgartner test- ed irrigant (NaOCl) extrusion from a root canal sealed with a permeable agarose gel.114 Significantly less extrusion oc- curred using the EndoVac sys- tem compared with positive- pressure needle irrigation. A well-controlled study by Gon- dim et al. found that patients experienced less postoperative pain, measured objectively and subjectively, when apical neg- ative-pressure irrigation was performed (EndoVac) than with apical positive-pressure irriga- tion.115 Efficacy In vitro and in vivo studies have demonstrated greater removal of debris from the apical walls and a statistically cleaner result using apical negative pressure irrigation in closed root-canal systems with sealed apices. In an in vivo study of 22 teeth by Siu and Baumgartner, less de- bris remained at 1 mm from working length using apical negative pressure compared with use of traditional needle ir- rigation, while Shin et al. found in an in vitro study of 69 teeth comparing traditional needle irrigation with apical negative pressure that these methods both resulted in clean root ca- nals, but that apical negative pressure resulted in less debris remaining at 1.5 and 3.5 mm from working length.46,104,116 When comparing root-canal debridement using manual dy- namic agitation or the EndoVac for final irrigation in a closed system and an open system, it was found that the presence of a sealed apical foramen ad- versely affected debridement efficacy when manual-dynamic agitation was used, but did not adversely affect results when the EndoVac was used. Apical negative-pressure irrigation is an effective method to over- come the fluid-dynamic chal- lenges inherent in closed root- canal systems.117 Microbial control Hockett et al. tested the abil- ity of apical negative pressure to remove a thick biofilm of E. Faecalis, finding that these specimens rendered nega- tive cultures obtained within 48 hours, while those irrigated using traditional positive-pres- sure irrigation were positive at 48 hours.99 One study found that apical negative-pressure irrigation resulted in similar bacterial re- duction to use of apical positive- pressure irrigation and a triple antibiotic in immature teeth.118 In a study comparing the use of apical positive-pressure ir- rigation and a triple antibiotic that has been utilized for pulpal regeneration/revascularisa- tion in teeth with incompletely formed apices (Trimix = Cipro, Minocin, Flagyl) versus use of apical negative-pressure irriga- tion with NaOCl, it was found that the results were statisti- cally equivalent for mineralized tissue formation and the repair process.119 Using apical nega- tive pressure and NaOCl also avoids the risk of drug resist- ance, tooth discoloration and allergic reactions.120,121 Conclusion Since the dawn of contempo- rary endodontics, dentists have been syringing NaOCl into the root canal space and then pro- ceeding to place endodontic instruments down the canal in the belief that they were carry- ing the irrigant to the apical ter- mination. Biological, scanning electron microscopy, light microscopy and other studies have proven this belief to be in error. NaOCl reacts with organic material in the root canal and quickly forms micro-bubbles at the api- cal termination that coalesce into a single large apical vapor bubble with subsequent instru- mentation. Because the apical vapor lock cannot be displaced via mechanical means, it pre- vents further NaOCl flow into the apical area. The safest method yet discov- ered to provide fresh NaOCl safely to the apical terminus to eliminate the apical vapor lock is to evacuate it via apical negative pressure. This method has also been proven to be safe because it always draws irri- gants to the source via suction — down the canal and simul- taneously away from the apical tissue in abundant quantities.122 When the proper irrigating agents are delivered safely to the full extent of the root-canal terminus, thereby removing 100 percent of organic tissue and 100 percent of the micro- bial contaminants, success in endodontic treatment may be taken to levels never seen be- fore. References 1 Friedman S, Mor C. The suc- cess of endodontic therapy— healing and functionality. J Calif Dent Assoc. 2004;32(6):493–503. 2 Orstavik D, Pittford T. Essen- tial endodontology: prevention and treatment of apical peri- odontitis. 2nd ed. Ames, IA: Blackwell Munksgaard Ltd; 2008:1. 3 Ricucci D, Siqueira JF Jr. Bio- films and apical periodontitis: study of prevalence and asso- ciation with clinical and histo- pathologic findings. J Endod. 2010;36(8);1277-88. 4 Fabricius L, Dahlen G, Sundqvist G, et al. Influence of residual bacteria on periapical tissue healing after chemome- chanical treatment and root fill- ing of experimentally infected monkey teeth. Eur J Oral Sci. 2006;114:278-85. 5 Siqueira JF Jr, Rocas IN. Clini- cal implications and microbiology of bacterial per- sistence after treatment procedures. J Endod. 2008;34:1291-301. 6 Wong R. Conventional endo- dontic failure and retreatment. Dent Clin North Am. 2004;48:265-89. 7 Basmadjian-Charles CL, Farge P, Bourgeois DM, Lebrun T. Factors influencing the long- term results of endodontic treat- ment: a review of the literature. Int Dent J. 2002;52:81-6. 8 Nair PN, Henry S, Cano V, Vera J. Microbial status of api- cal root canal system of hu- man mandibular first molars with primary apical periodon- titis after “one-visit” endodontic reatment. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2005;99:231-52. 9 Gu LS, Kim JR, Ling J, Choi KK, Pashley DH, Tay FR. Review of contemporary irrigant agita- tion techniques and devices. J Endod. 2009;35(6):791-804. Editorial note: A complete list of references is available from the publisher. This article has been reprinted in part from G. Glassman, Safe- ty and Efficacy Considerations in Endodontic Irrigation (Pen- Well, January 2011). Dr. Gary Glassman graduated from the University of Toronto, Faculty of Dentistry in 1984. He graduated from the Endodontol- ogy Program at Temple Univer- sity in 1987, where he received the Louis I. Grossman Study Club Award for academic and clinical proficiency in endodon- tics. The author of numerous publi- cations, Glassman lectures glob- ally on endodontics, is on staff at the University of Toronto, Fac- ulty of Dentistry in the graduate department of endodontics, and adjunct professor of dentistry and director of endodontic pro- gramming for the University of Technology, Kingston, Jamaica. He is a fellow of the Royal Col- lege of Dentists of Canada, fel- low of the American College of Dentists, and the endodontic editor for Oral Health Dental Journal. He maintains a private practice, Endodontic Specialists, in Toronto, Ontario, Canada. He can be reached at gary@rootca- nals.ca. About the Author Fig. 2: EndoVac setup. (Images/Provided by Gary Glassman, DDS, FRCD(C)) Fig. 3: Irrigation accident with wide- spread trauma.

Pages Overview