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6 Dental Tribune Middle East & Africa Edition | May - June 2014mcme > Page 7 Passive micro-volume management of sodium hypochlorite in endodontic treatment By Les Kalman, B.Sc (Hon), DDS T he passive utilization and micro-volume management of so- dium hypochlorite as an endodontic irrigant has been illustrated with a labora- tory demonstration and sev- eral clinical cases. By limit- ing the volume and pressure of sodium hypochlorite, the injurious effects can be mini- mized while still benefiting from the ideal disinfecting characteristics. Further stud- ies are required to understand the behavior of fluids, espe- cially sodium hypochlorite, within the context of perme- ability, fluid mechanics and multiphase fluid flow through porous media. Introduction Endodontic treatment ad- dresses the removal of the tooth’s internal pulp and mi- croorganisms, 1 primarily due to infection and necrosis. Once proper diagnosis and prog- nosis has been established, the patient has the option of maintaining the tooth’s form and function while the vital- ity becomes lost. Current en- dodontic treatment consists of utilizing rotary files to remove the pulpal tissue and shape the internal dentin chamber of the tooth. Chemicals, in the form of gels and liquids, are then implemented to disin- fect the canal(s) and eliminate bacteria.2 The chemicals are then dried and the canal space filled with either gutta-percha or resin to create a hermetic seal. The chemicals employed to clean and disinfect the intra- canal space are vast and in- clude file lubricants such as Prolube (DENTSPLY) and ir- rigants such as QMix (DENT- SPLY). During clinical endo- dontics, the canal is filled with a cocktail of chemicals, as file lubricants and irrigants be- come a mixture. Chlorhexidine gluconate (CHX) is an uncommonly used irrigant3 with several desir- able properties. It provides antimicrobial activity against certain aerobic and anaero- bic bacteria, exhibits no sig- nificant changes in bacterial resistance in the oral micro- bial environment and has no injurious effect to the skin or mucosa.4 In fact, CHX has a role as an oral rinse at the 0.12 percent concentration.4 Sodium hypochlorite (NaOCl) still remains the most com- monly used chemical,2,3 be- cause of its availability, cost and effectiveness.2,5 Sodium hypochlorite is effective against broad-spectrum bac- teria and has the ability to dis- solve both vital and necrotic tissue.6 However, this irrigant is equally damaging to the pa- tient and has a history of in- jurious effects.5 Typically the NaOCl is delivered into the ca- nal space with a syringe dose of 2-10 ml that is expelled under pressure. The abil- ity of NaOCl to escape either through poorly sealed isola- tion or other means can cause serious injury to the patient.5 Injury from NaOCl is well es- tablished in the literature3,5,6 and has been attributed to three main errors: poor han- dling, injection beyond the apical foramen and allergy.6 Poor handling injury can re- sult in operator and/or patient injury to the eye and/or skin.6 Injection beyond the apical foramen can result in the fol- lowing:6 • immediate and severe pain • edema to adjacent tissue • edema to the lip, infraor- bital region and side of face • intense bleeding from within the canal space • skin and mucosa bleeding • intestinal bleeding • paraesthesia • secondary infection. Allergy from NaOCl is rare but has been reported and may result in severe pain, a burning sensation, edema and transient paraesthesia.6 Methodology Although there is no univer- sally accepted irrigation pro- tocol regarding endodontic treatment,3 it is the duty of clinicians to apply evidence- based dentistry within clini- cal parameters to provide their patients with the highest standard of care with minimal morbidity. The use of NaOCl has numerous beneficial fac- tors that maximize treatment success; however, it is the ap- plication of the liquid that can cause injury. Micro-volume management of NaOCl has been proposed. The concept is based on the premise that endodontic in- struments have irregular surfaces, crucial for dentinal preparation, and that liq- uids exhibit surface tension characteristics.7 By placing an instrument into a suitable container, the NaOCl will be carried within the surface tex- ture of the instrument (Figs. 1, 2). As the operator inserts the instrument into the canal (Fig. 3), the NaOCl is carried with it. Upon instrument move- ment, the NaOCl is released into the canal space (Fig. 4). Surface tension and permea- bility of porous media (dentin) will also increase the ability of the liquid to percolate into the canal.7 This approach is radi- cally different than current philosophies, as the NaOCl is introduced into the ca- nal space in a micro-volume amount without any pressure. The operator has control of the minimized liquid while benefitting from its effective- ness. The micro-volume manage- ment of sodium hypochlorite has been applied to numerous clinical cases. Post-operative obturation radiographs of completed clinical cases have been presented (Figs. 5–9). Discussion 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 Centre for Advanced Professional Practices (CAPP) is an ADA CERP Recognized Provider. ADA CERP is a service of the American Dental Association to assist dental professionals in identifying quality providers of continuing dental education. ADA CERP does not approve or endorse individual courses or instructors, nor does it imply acceptance of credit hours by boards of dentistry. CAPP designates this activity for 2 CE credits. Fig. 1 DENTSPLY Vortex rotary file with sodium hypochlorite. (Photos/Provided by Les Kalman, B.Sc (Hon), DDS) Fig. 3 Micro-volume delivery of sodium hypochlo- rite with rotary file. Fig. 2 DENTSPLY Profile rotary file with dyed sodium hypochlorite. Fig. 4 Sodium hypochlorite in block with rotary file. Thecanalsysteminsideatooth is very complex. Although there is the presence of one or more canals, there also exist numerous micro tunnels, rib- bons and sheets throughout the canal network.8 The ca- nals are also housed within a porous dentinal structure, for which the permeability has been distinguished.9 Although the elimination of the pulp is a relatively predictable clinical procedure, the introduction of liquids into this complex micro-network porous devel- opment further complicates matters. If the clinician intro- mize its bactericidal effects yet minimize its injurious effects. Surface tension fluid mechan- ics and permeability7,10,11 sug- gest that the NaOCl can be carried within the surface ir- regularities of endodontic in- strumentation and deposited into the canal space and per- colate within the complex net- work of the canal. The passive management of the irrigant in micro-volume would greatly reduce complications due to poor handling. CHX has duces liquids, then the suc- cessful removal of those liq- uids is key to clinical success. Concepts of multiphase fluid flow through porous media, and capillaries, 10 permeabil- ity of porous media11 and sur- face tension fluid mechanics7 must be recognized to validate and further advance canal ir- rigation. Micro-volume management of NaOCl has been suggested as a delivery modality to maxi-