SODIUM HYPOCHLORITE By Dr.Anoop.V.Nair PG, Dept of Cons Dentistry & Endodontics
CONTENTS • Introduction • Root canal bacterium • Root canal irrigants • Ideal requirements of a root canal irrigant • Natural occurrence of NaOCl • History of NaOCl • Chemistry of NaOCl • Mode of action • Suggested irrigation regimen • Efficacy • Time factor • Interactions • Accidents and management • Literature discussion • Conclusion • References
• Main cause of endodontic failure- Microorganisms, either remaining in the root canal space after treatment or re-colonizing the fil ed canal system. • Primary endodontic treatment goal- optimize root canal disinfection and to prevent re-infection. • Pulpitis is the host reaction to opportunistic pathogens from the oral environment entering the endodontium. • Vital pulp tissue can defend against microorganisms and is thus largely noninfected until it gradual y becomes necrotic. In contrast, the pulp space of nonvital teeth with radiographic signs of periapical rarefaction always harbors cultivable microorganisms. • Consequently, the treatment of vital cases should focus on asepsis, i.e. the prevention of infection entering a primarily sterile environment, which is the apical portion of the root canal. Antisepsis, which is the attempt to remove al microorganisms, is the key issue in nonvital cases.
• Success, longevity, and reliability of modern endodontic treatments- effectiveness of endodontic files, rotary instrumentation, irrigating solutions, and chelating agents to clean, shape, and disinfect root canals. • The role of microorganisms in the development and perpetuation of pulp and periapical diseases has clearly been demonstrated in animal models and human studies. • Elimination of microorganisms from infected root canals is a complicated task. • The chances of a favourable outcome with root canal treatment are significantly higher if infection is eradicated ef ectively before the root canal system is obturated. • However, if microorganisms persist at the time of obturation, or if they penetrate into the canal after obturation, there is a high risk of treatment failure
• Self-aggregates of monobacterial morphotypes and coaggregates of dif erent bacterial morphotypes are also found adhering to teeth. • The interbacterial spaces are occupied by an amorphous material, spirochetes, and hyphal-like structures that are suggestive of fungi. • Costerton et al. used the term “biofilm” to describe this clustering of bacteria. Bacteria within a biofilm have increased resistance to a variety of external hostile influences, such as the host defense responses, antibiotics, antiseptics, and shear forces, compared with isolated bacterial cel s. * F. J. Vertucci, “Root canal anatomy of the human permanent teeth,” Oral Surgery Oral Medicine and Oral Pathology, vol. 58, no. 5, pp. 589–599, 1984.
• Numerous measures have been described to reduce the number of microorganisms in the root canal system, including the use of various instrumentation techniques, irrigation regimens, and intracanal medicaments. • The use of chemical agents during instrumentation to completely clean al aspects of the root canal system is central to successful endodontic treatment. Irrigation is complementary to instrumentation in facilitating the removal of pulp tissue and/or microorganisms. • Irrigation dynamics plays an important role; the ef ectiveness of irrigation depends on the working mechanism(s) of the irrigant and the ability to bring the irrigant in contact with the microorganisms and tissue debris in the root canal.
Root Canal Bacterium • Primary root canal infections are polymicrobial, typical y dominated by obligatory anaerobic bacteria. • The most frequently isolated microorganisms before root canal treatment include Gram-negative anaerobic rods, Gram-positive anaerobic cocci, Gram-positive anaerobic and facultative rods, Lactobacil us species, and Gram-positive facultative Streptococcus species. • The obligate anaerobes are rather easily eradicated during root canal treatment. • Facultative bacteria such as nonmutans Streptococci, Enterococci, and Lactobacil i, once established, are more likely to survive chemomechanical instrumentation and root canal medication. • Enterococcus faecalis has gained attention in the endodontic literature, as it can frequently be isolated from root canals in cases of failed root canal treatments. • Yeasts may also be found in root canals associated with therapy-resistant apical periodontitis.
Root Canal Irrigants • It is general y believed that mechanical enlargement of canals must be accompanied by copious irrigation in order to facilitate maximum removal of microorganisms so that the prepared canal becomes as bacteria-free as possible. • Ideal y an irrigant should provide a mechanical flushing action, be microbiocidal and dissolve remnants of organic tissues without damaging the periradicular tissues if extruded into the periodontium. • In addition, the root canal irrigants should be biocompatible with oral tissues.
Ideal Requirement of Root Canal Irrigants It appears evident that root canal irrigants ideal y should (i) have a broad antimicrobial spectrum and high efficacy against anaerobic and facultative microorganisms organized in biofilms (i ) dissolve necrotic pulp tissue remnants, (iii) inactivate endotoxin, (iv) prevent the formation of a smear layer during instrumentation or dissolve the latter once it has formed, (v) be systemical y nontoxic, (vi) be non caustic to periodontal tissues, (vi ) be little potential to cause an anaphylactic reaction.
• Have a broad antimicrobial spectrum and high efficacy against anaerobic and facultative microorganisms organized in biofilms ● Dissolve necrotic pulp tissue remnants ● Inactivate endotoxin ● Prevent the formation of a smear layer during instrumentation or dissolve the latter once it has formed. Furthermore, as endodontic irrigants come in contact with vital tissues, they should be systemical y nontoxic, non caustic to periodontal tissues and have little potential to cause an anaphylactic reaction. Root Canal Irrigants , J Endod 2006;32:389–398 Matthias Zehnder
• A large number of substances have been used as root canal irrigants, including acids (citric and phosphoric), chelating agent (ethylene diaminetetraacetic acid EDTA), proteolytic enzymes, alkaline solutions (sodium hypochlorite, sodium hydroxide, urea, and potassium hydroxide), oxidative agents (hydrogen peroxide and Gly-Oxide), local anesthetic solutions, and normal saline. • The most widely used endodontic irrigant is 0.5% to 6.0% sodium hypochlorite (NaOCl), because of its bactericidal activity and ability to dissolve vital and necrotic organic tissue. • However, NaOCl solutions exert no ef ects on inorganic components of smear layer. • Chelant and acid solutions have been recommended for removing the smear layer from instrumented root canals, including ethylene diaminetetraacetic acid (EDTA), citric acid, and phosphoric acid
• Sodium hypochlorite is the most commonly used endodontic irrigant, despite limitations. None of the presently available root canal irrigants satisfy the requirements of ideal root canal irrigant. Newer root canal irrigants are studied for potential replacement of sodium hypochlorite. Newer Root Canal Irrigants in Horizon: A Review Sushma Jaju and Prashant P. Jaju International Journal of Dentistry Volume 2011 (2011), Article ID 851359, 9 pages doi:10.1155/2011/851359
• Most commonly used irrigating solution • Excel ent antibacterial agent • Capable of dissolving necrotic tissue, vital pulp tissue, organic components of dentin and biofilms • Bleach- disinfectant or bleaching agent • Irrigant of choice in endodontics, ef icacy against pathogenic organisms and pulp digestion • low viscosity al owing easy introduction into the canal architecture* • acceptable shelf life* • easily available and inexpensive* * Review: the use of sodium hypochlorite in endodontics — potential complications and their management H. R. Spencer, V. Ike& P. A. Brennan:British Dental Journal 202, 555 - 559 (2007)
Natural Occurrence • Chlorine is one of the most widely distributed elements on earth. It is not found in a free state in nature, but exists in combination with sodium, potassium, calcium, and magnesium. • In the human body, chlorine compounds are part of the nonspecific immune defense. • They are generated by neutrophils via the myeloperoxidase-mediated chlorination of a nitrogenous compound or set of compounds.
HISTORY • Potassium hypochlorite was the first chemical y produced aqueous chlorine solution, invented in France by Berthol et (1748-1822). • Starting in the late 18th century, this solution was industrial y produced by Percy in Javel near Paris, hence the name “Eau de Javel”. • First, hypochlorite solutions were used as bleaching agents. • Subsequently, sodium hypochlorite was recommended by Labarraque (1777-1850) to prevent childbed fever and other infectious diseases. • Based on the control ed laboratory studies by Koch and Pasteur, hypochlorite then gained wide acceptance as a disinfectant by the end of the 19th century.
• In World War I, the chemist Henry Drysdale Dakin and the surgeon Alexis Carrel extended the use of a buffered 0.5% sodium hypochlorite solution to the irrigation of infected wounds, based on Dakin’s meticulous studies on the ef icacy of dif erent solutions on infected necrotic tissue. • Beside their wide-spectrum, nonspecific kil ing efficacy on al microbes, hypochlorite preparations are sporicidal, virucidal, and show far greater tissue dissolving effects on necrotic than on vital tissues. • These features prompted the use of aqueous sodium hypochlorite in endodontics as the main irrigant as early as 1920. • Other chlorine-releasing compounds have been advocated in endodontics, such as chloramine-T and sodium dichloroisocyanurate. • These, however, have never gained wide acceptance in endodontics, and appear to be less ef ective than hypochlorite at comparable concentration.
CHEMISTRY • Reactive chlorine in aqueous solution at body temperature can, in essence, take two forms: hypochlorite (OCl-) or hypochlorous acid (HOCl). • The concentration of these can be expressed as available chlorine by determining the electrochemical equivalent amount of elemental chlorine. According to the fol owing equations: • Therefore, 1 mol of hypochlorite contains 1 mol of available chlorine. • The state of available chlorine is depending on the pH of the solution. • Above a pH of 7.6, the predominant form is hypochlorite, below this value it is hypochlorous acid. • Both forms are extremely reactive oxidizing agents. • Pure hypochlorite solutions as they are used in endodontics have a pH of 12, and thus the entire available chlorine is in the form of OCl-.
• However, at identical levels of available chlorine, hypochlorous acid is more bactericidal than hypochlorite. • One way to increase the efficacy of hypochlorite solutions could thus be to lower their pH. • One alternative approach to improve the effectiveness of hypochlorite irrigants in the root canal system could be to increase the temperature of low-concentration NaOCl solutions. This improves their immediate tissue-dissolution capacity. • Furthermore, heated hypochlorite solutions remove organic debris from dentin shavings more efficiently than unheated counterparts.
• Ultrasonic activation of sodium hypochlorite has also been advocated, as this would “accelerate chemical reactions, create cavitational effects, and achieve a superior cleansing action”. • However, results obtained with ultrasonical y activated hypochlorite versus irrigation alone are contradictory, both in terms of root canal cleanliness and remaining microbiota in the infected root canal system after the cleaning and shaping procedure. • The observed effects of ultrasonic activation, if any, were relatively minor. • Ultrasonic energy may simply produce heat, thus rendering the hypochlorite slightly more active.
MODE OF ACTION • In use for almost a century • Possesses broad spectrum antimicrobial activity against endodontic microorganisms and biofilms, including microbiota dif icult to eradicate from root canals such as Enterococcus, Actinomyces and Candida • Dissolves organic material such as pulp tissue and col agen • Bacteria inside main root canal, lateral canals and dentinal tubules- if in direct contact with irrigant- are destroyed. • Sodium hypochlorite reacts with fatty acids and amino acids in dental pulp resulting in liquefaction of organic tissue. • There is no universal y accepted concentration of sodium hypochlorite for use as an endodontic irrigant. • The antibacterial and tissue dissolution action of hypochlorite increases with its concentration, but this is accompanied by an increase in toxicity.
• Dakin’s original 0.5% sodium hypochlorite solution was designed to treat open (burnt) wounds, it was surmised that in the confined area of a root canal system, higher concentrations should be used, as they would be more efficient than Dakin’s solution • The antibacterial effectiveness and tissue dissolution capacity of aqueous hypochlorite is a function of its concentration. • Severe irritations have been reported when such concentrated solutions were inadvertently forced into the periapical tissues during irrigation or leaked through the rubber dam • Furthermore, a 5.25% solution significantly decreases the elastic modulus and flexural strength of human dentin compared to physiologic saline, while a 0.5% solution does not.
• The reduction of intracanal microbiota, on the other hand, is not any greater when 5% sodium hypochlorite is used as an irrigant as compared to 0.5%. • From in vitro observations, it would appear that a 1% NaOCl solution should suf ice to dissolve the entire pulp tissue in the course of an endodontic treatment session. • It must be realized that during irrigation, fresh hypochlorite consistently reaches the canal system, and concentration of the solution may thus not play a decisive role. • Unclean areas may be a result of the inability of solutions to physical y reach these areas rather than their concentration. • Hence, based on the currently available evidence, there is no rationale for using hypochlorite solutions at concentrations over 1% wt/vol.
Infected dentin blocks- 0.25% sufficient to kil E.faecalis in 15 mins, conc of 1% requires 1 hr to kil Candida albicans * Ruf et al., in infected extracted teeth, found that 1 min application of 6% NaOCl and 2% chlorhexidine equal y ef ective in eliminating microorganisms and statistical y significantly superior to MTAD and 17% EDTA in eliminating Candida albicans infections
• Commercial y available household bleach- Clorox 6.15% NaOCl, alkaline pH- 11.4, hypertonic • Some authors recommend, dilution of clorox with 1% bicarbonate, instead of water to bring down pH to a lower level. • Others do not see any reduction in aggressiveness on fresh tissue by buffering NaOCl and recommend dilution with water to obtain less conc. irrigation solutions. * Splangberg LSW, Haapasalo M: Rationale and efficacy of root canal medicaments and root fil ing material with emphasis on treatment outcome.Endod Topics 2:35,2002
SUGGESTED IRRIGATION REGIMEN • The chemicals used to clean infected canals should be administered in such manner that they can unleash their full potential on their targets in the root canal rather than act on each other. • Hence, a hypochlorite solution should be employed throughout instrumentation, without altering it with EDTA or citric acid. • ‘Canals should always be fil ed with sodium hypochlorite’. • This wil increase the working time of the irrigant. • In addition, cutting ef icacy of hand instruments is improved and torsional load on rotary nickel-titanium instruments is reduced in fluid-fil ed environments compared to dry conditions. • On the other hand, corrosion of instruments in prolonged contact with hypochlorite is an issue. • Submersing instruments for hours in a hypochlorite solution wil induce corrosion. • However, no adverse effects should be expected during the short contact periods when an instrument is manipulated in a root canal fil ed with hypochlorite.
• After the smear removing procedure a final rinse with an antiseptic solution appears beneficial. The choice of the final irrigant depends on the next treatment step, i.e. whether an inter visit dressing is planned or not. • If calcium hydroxide is used for the interim, the final rinse should be sodium hypochlorite, as these two chemicals are perfectly complementary. It appears even advantageous to mix calcium hydroxide powder with the sodium hypochlorite irrigant rather than with saline to obtain a more ef ective dressing. • Chlorhexidie- promising agent to be used as a final irrigant. It has an affinity to dental hard tissues, and once bound to a surface, has prolonged antimicrobial activity, a phenomenon cal ed substantivity. • ‘Substantivity is not observed with sodium hypochlorite.’
EFFICACY- • Enterococci- 1 min of 6% solution reduced biofilm by 7-8 orders of magnitude 15 min at 0.25% in contaminated dentin blocks 30 min at 0.5% and 2 min at 5.25% in direct contact with bacteria • Actinomyces organisms- 1 min at 1% solution 10 sec at 0.5% in direct contact with bacteria • Candida organisms- 1 hour at 1% or 5% solution on root dentin with smear layer 30 sec for both the 0.5% solutions to kil al cel s in culture 1 min of 6% solution: no growth
• Principal ingredient- unbound chlorine, solution must be replenished frequently during preparation to compensate for lower concentrations and to constantly renew the fluid inside the root canal. • More important- when canal is narrow and smal , files must carry the NaOCl to the apical third during instrumentation. • 1% solution- effective, at dissolving tissue and providing an antimicrobial effect. • 6% commercial household bleach undiluted- substantial necrosis of wound area and may result in serious clinical side effects. • Diluted 1:1 or 1:3 ratio with water- 2.5% or 1% solution suitable for clinical endodontic use.
Increasing efficacy of hypochlorite preparations • Increasing temperature of low concentration NaOCl solutions- which improve their immediate tissue-dissolution capacity. • Heated hypochlorite solutions remove organic debris from dentin shavings more ef iciently • Antimicrobial properties of heated NaOCl- bactericidal rates more than doubled for each 5O rise in temperature in the range of 5-600.
Device for heating syringes filled with irrigation solution before use. Syringe warmer (Vista dental products, Racine) Effect of heating on NaOCl (0.5%) to dissolve pulp tissue, positive control 5.25%. (Sirtes G, Waltimo T, Schaetzle M, Zehnder M: The effects of temperature on sodium hypochlorite short-term stability, pulp dissolution capacity and antimicrobial efficacy. J Endod 31:669-671, 2005)
• Studies have shown that 1 min at 47oc is the cutof exposure at which osteoblasts can stil survive, however, higher temperatures may infact be suf icient to kil osteoblasts and other host cel s. • Warming of NaOCl to 50oc or 60oc increases col agen dissolution and disinfecting potential, but it may also have severely detrimental ef ects on NiTi instruments, causing corrosion of the metal surface after immersion for 1 hour Rotary instrument immersed for 2 hours in NaOCl heated to 60oc, showing severe corrosion
• A study using steady state planktonic E.fecalis cel s, showed a temperature rise of 25oc increased NaOCl efficacy by a factor of 100. • Capacity to dissolve human dental pulp using 1% NaOCl at 45oc was found to be equal to that of a 5.25% solution at 20oc. • Systemic toxicity of preheated low conc of NaOCl irrigants should be less than that of a more concentrated unheated solution.
Time factor • NaOCl require an adequate working time to reach their potential. • Chlorine, which is responsible for dissolving and antibacterial capacity of NaOCl- unstable and consumed rapidly during the first phase of tissue dissolution, probably within 2 mins. • Optimal time a hypochlorite irrigant needs to remain in the canal system is an issue yet to be resolved. * Cohen- Pathways of the pulp, 10th edition
INTERACTIONS • Antimicrobial activity, dissolving of the remaining pulp tissues, lubrication during mechanical instrumentation, availability and low cost are the fundamental requirements for root canal irrigants (Zehnder 2006, Haapasalo et al. 2010). • Sodium hypochlorite-most common irrigant, other solutions mostly used along with sodium hypochlorite, as a final rinse to enhance the antimicrobial activity and substantivity against some resistant bacteria, to decrease the caustic effect or to aid in removing the smear layer. (Zehnder 2006, Mohammadi & Abbott 2009, Haapasalo et al. 2010).
NaOCl has been reported to cause dentine discolouration, although it is a bleaching agent. This discolouration is a result of its contact with erythrocytes and its high tendency to crystallize on the root dentine, which may mean that it is difficult to completely remove from the canal (Gutie´rrez & Guzma´n 1968). In addition, the combination of NaOCl with other adjunct irrigating solutions has been found to cause marked tooth discolourations Vivacqua-Gomes et al. (2002) observed a dark brown precipitate when NaOCl was combined with chlorhexidine (CHX) gel. Other authors have reported the same type of discolouration when NaOCl has been used with CHX solutions (Basrani et al. 2007, Marchesan et al. 2007, Bui et al. 2008, Akisue et al. 2010, Krishnamurthy & Sudhakaran 2010, Nassar et al. 2011, Souza et al. 2011)
Discolouration when irrigants are combined. (a) 2.63% NaOCl + 2% chlorhexidine (CHX) (dark brown precipitate); (b) 18% EDTA + 2% CHX (cloudy blue); (c) 2.63% NaOCl + 18% EDTA (no discolouration) d) 2.63% NaOCl + 20% Citric acid (white precipitate and the solution turns cloudy after shaking).
This dark brown precipitate can stain the dentine, adhere to the floor of the pulp chamber, access cavity and root canal wal s and act as a residual film that may compromise the diffusion of intra-canal medicaments into the dentine, disrupt the adhesion of the root canal filling and favour coronal restoration breakdown (Vivacqua-Gomes et al. 2002, Akisue et al. 2010) Discolouration potential of NaOCl/CHX combination on the access cavity walls. (a) NaOCl (b) Dark brown precipitate after NaOCl/CHX combination (c) The precipitate becomes adherent to the access cavity walls (white arrow) and crown fissures (red arrow) even after flushing with distilled water.
Basrani et al. (2007) examined this precipitate using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS), and they found that it contains a significant amount of parachloroaniline (PCA). This substance is carcinogenic and it can further degrade to 1-chloro-4- nitrobenzene, which also is carcinogenic. However, by using nuclear magnetic resonance (NMR), Thomas & Sem (2010) reported that mixing NaOCl and CHX did not produce PCA at any measurable quantity, but one of the CHX breakdown products may be further metabolized to PCA (Nowicki & Sem 2011).
As a result of these possible hazards, Kim et al. (2012) examined the chemical interaction between Alexidine (ALX), as a substitute for CHX, and NaOCl using electrospray ionization mass spectrometry (ESIMS) and scanning electron microscopy (SEM). The results revealed that the association of ALX/NaOCl did not produce PCA or any precipitate, and the mixing solutions of ALX and NaOCl resulted in a slight discolouration ranging from light yellow to transparent as the ALX concentration decreased. In addition, this combination did not stain dentine and was easy to remove from the root canal by irrigation.
NaOCl also reacts with MTAD (a mixture of a tetracycline isomer, an acid [citric acid], and a detergent) (Dentsply Tulsa Dental, Tulsa, OK, USA), in the presence of light, causing brown discolouration (Torabinejad et al. 2003). This reaction may be caused by the dentinal absorption and release of the doxycycline, present in MTAD, which will be exposed to NaOCl if it is used as a final rinse after MTAD (Torabinejad et al. 2003).
Tay et al. (2006a) formation of yellow precipitate along the root canal walls when NaOCl was used as an irrigant and then followed by the application of BioPure MTAD as a final rinse. They also observed red-purple staining of light-exposed, root-treated dentine when the root canals were rinsed with 1.3% NaOCl as an initial rinse followed by MTAD as the final rinse.
This photo-oxidative degradation process was probably triggered by the use of NaOCl as an oxidizing agent which also resulted in partial loss of its antimicrobial substantivity (Tay et al. 2006a,b). The chemical reaction between NaOCl and citric acid, which leads to the formation of a white precipitate, indicates a complex interaction between NaOCl and MTAD that requires further investigations to validate the safety and usefulness of this combination of irrigants. Gonza´lez-Lo´pez et al. (2006) and Rasimick et al. (2008) have reported interactions between CHX and EDTA irrigants with the formation of white to pink precipitate.
Practitioners should choose irrigating solutions carefully to suit the clinical condition that is being treated. If CHX is chosen, then the insoluble dark brown precipitate, created when NaOCl and CHX are mixed, can be avoided by incorporating a thorough intermediate flush between each irrigant – this can be carried out with solutions such as saline or sterile distilled water, followed by drying of the canal before the next solution is used (Krishnamurthy & Sudhakaran 2010). Absolute alcohol has also been suggested as an intermediate flush but its biocompatibility with the periapical tissues and interactions with other irrigants remain a concern (Krishnamurthy & Sudhakaran 2010, Valera et al. 2010)
Nassar et al. (2011) recommended the use of sodium ascorbate to prevent the formation of this precipitate. Ascorbic acid solution, as a reducing agent, has been advocated as an intermediate flush between NaOCl and MTAD, to prevent the oxidation effect of NaOCl and to avoid the photodegradation of the doxycycline that is present in MTAD (Tay et al. 2006a). In addition, the possible interaction between NaOCl and citric acid would be avoided. A cloudy precipitate forms when EDTA and CHX are combined. Maleic acid (MA), which has been found to be less cytotoxic and more effective in smear layer removal than EDTA (Ballal et al. 2009a,b), can be used as a substitute for EDTA, and the combination of MA and CHX has not shown any precipitate formation or discolouration (Ballal et al. 2011).
Tooth discolouration associated with root canal irrigants Irrigating solutions Type of discolouration Author/s – year NaOCl (undiluted and 10%) Some discolouring effect Gutie´ rrez and Guzma´n (1968) 1% NaOCl + 2% chlorhexidine (CHX) gel Dark brown precipitate Vivacqua-Gomes et al. (2002) MTAD + NaOCl (5.25–0.65%) Brown solution (NaOCl final rinse) Torabinejad et al. (2003) 17% EDTA + 1% CHX sol. Pink precipitate (CHX final rinse) Gonza´ lez-Lo´ pez et al. (2006) 2% CHX sol. + 17% EDTA White precipitate Rasimick et al. (2008) 1.54–6.15% NaOCl + MTAD Yellow precipitate (MTAD final rinse) Tay et al. (2006a) (Clinical application) 1.3% NaOCl + MTAD Red-purple (MTAD final rinse) Tay et al. (2006a) (In vitro study) NaOCl + CHX sol. Light orange to dark brown Basrani et al. (2007), Marchesan et al(2007), according to conc. Bui et al. (2008) Akisue et al. (2010), Krishnamurthy & Sudhakaran (2010), Nassar et al. (2011) 2% CHX sol. + 15% Citric acid A white solution but returns Akisue et al. (2010) colourless and easily removed during irrigation with CHX 2% CHX gel + 5.25% NaOCl Discoloured enamel and dentine Souza et al. (2011) 2% CHX sol. + 5.25% NaOCl Discoloured dentine only Souza et al. (2011) 2% CHX gel + 5.25% NaOCl + 17% EDTA Discoloured enamel and dentine Souza et al. (2011) 2% CHX sol. + 5.25% NaOCl + 17% EDTA Discoloured dentine Souza et al. (2011)
ALLERGIC REACTIONS • Unlikely to occur, since both sodium and chlorine are essential elements in the physiology of human body • Hypersensitivity and contact dermatitis- rare cases • In cases of hypersensitivity- chlorhexidine should not be used either- due to chlorine content • Alternative irrigant- iodine potassium iodide, high antimicrobial ef icacy • Alcohol, tap water- less effective against microorganisms, do not dissolve vital or necrotic pulp tissue. • Ca(OH)2- temporary medicament, dissolves both vital and necrotic tissue.
• The allergic potential of sodium hypochlorite was first reported in 1940 by Sulzberger and subsequently by Cohen and Burns. • Caliskan et al. presented a case where a 32-year-old female developed rapid onset pain, swelling, difficulty in breathing and subsequently hypotension following application of 0.5 ml of 1% sodium hypochlorite. The patient required urgent hospitalization in the intensive care unit and management with intravenous steroids and antihistamines. • Subsequent allergy skin scratch test performed two weeks after the patient was discharged confirmed a highly positive result to sodium hypochlorite. The usefulness of this test in suspected cases of sodium hypochlorite allergy during endodontic treatment has been confirmed by Kaufman and Keila. • Symptoms of allergy and possible anaphylaxis- urticaria, oedema, shortness of breath, wheezing (bronchospasm) and hypotension. • Urgent referral to a hospital following first aid management is recommended. Review: the use of sodium hypochlorite in endodontics — potential complications and their management H. R. Spencer, V. Ike& P. A. Brennan:British Dental Journal 202, 555 - 559 (2007)
• To avoid extrusion and serious damage to periapical tissues, irrigation needles should never be wedged into canals during irrigation. • Higher concentration NaOCl- more aggressive toward living tissue and can cause severe injuries when forced into periapical area. 27 gauge needle 30 gauge side venting needle
Toxic effect of sodium hypochlorite on periradicular tissues. After root canal treatment of the first molar, the patient reported pain A. On a return visit, an abscess was diagnosed and incised. B. Osteonecrosis was evident after 3 weeks.
These accidents can be prevented- • Mark the working length on the irrigation needle with a bend or rubber stop and passively expressing the solution from the syringe into the canal. • Needle should be continuously moved up and down. • It should remain loose in the canal, al owing a backflow of liquid. • The goal is to rinse the suspended, concentrated dentinal filings out of the pulp chamber and root canals as new solution is brought down into the most apical areas by the endodontic instrument and capil ary ef ect. • Patency files should not be extended farther than the periodontal ligament because they are possible sources of irrigant extrusion
Complications of accidental spillage 1) Damage to clothing Accidental spil age of sodium hypochlorite is probably the most common accident to occur during root canal irrigation. Even spillage of minute quantities of this agent on clothing will lead to rapid, irreparable bleaching. The patient should wear a protective plastic bib, and the practitioner should exercise care when transferring syringes filled with hypochlorite to the oral cavity. 2) Eye damage Seemingly mild burns with an alkali such as sodium hypochlorite can result in significant injury as the alkali reacts with the lipid in the corneal epithelial cells, forming a soap bubble that penetrates the corneal stroma. The alkali moves rapidly to the anterior chamber, making repair difficult. Further degeneration of the tissues within the anterior chamber results in perforation, with endophthalmitis and subsequent loss of the eye.
• Ingram recorded a case of accidental spillage of 5.25% sodium hypochlorite into a patient's eye during endodontic therapy. • The immediate symptoms included instant severe pain and intense burning, profuse watering (epiphora) and erythema. • Loss of epithelial cells in the outer corneal layer may occur. • There may be blurring of vision and patchy colouration of the cornea. • Immediate ocular irrigation with a large amount of water or sterile saline is required followed by an urgent referral to an ophthalmologist. • The referral should ideally be made immediately by telephone to the nearest eye department. • The use of adequate eye protection during endodontic treatment should eliminate the risk of occurrence of this accident, but sterile saline should always be available to irrigate eyes injured with hypochlorite. • It has been advised that eyes exposed to undiluted bleach should be irrigated for 15 minutes with a litre of normal saline.
3) Damage to skin • Skin injury with an alkaline substance requires immediate irrigation with water as alkalis combine with proteins or fats in tissue to form soluble protein complexes or soaps. These complexes permit the passage of hydroxyl ions deep into the tissue, thereby limiting their contact with the water dilutant on the skin surface. • Water is the agent of choice for irrigating skin and it should be delivered at low pressure as high pressure may spread the hypochlorite into the patient's or rescuer's eyes. 4) Damage to oral mucosa • Surface injury is caused by the reaction of alkali with protein and fats as described for eye injuries above. Swallowing of sodium hypochlorite requires the patient to be monitored following immediate treatment. It is worth noting that skin damage can result from secondary contamination. Review: the use of sodium hypochlorite in endodontics — potential complications and their management. H. R. Spencer, V. Ike& P. A. Brennan:British Dental Journal 202, 555 - 559 (2007)
Complications arising from hypochlorite extrusion beyond the root apex 1) Chemical burns and tissue necrosis • When sodium hypochlorite is extruded beyond the root canal into the peri- radicular tissues, the effect is one of a chemical burn leading to a localised or extensive tissue necrosis. • Given the widespread use of hypochlorite, this complication is fortunately very rare indeed. • A severe acute inflammatory reaction of the tissues develops. • This leads to rapid tissue swelling both intra orally within the surrounding mucosa and extra orally within the skin and subcutaneous tissues. • The swelling may be oedematous, haemorrhagic or both, and may extend beyond the region that might be expected with an acute infection of the affected tooth.
Bruising and oedema of patients who presented with hypochlorite extrusion into the soft tissues
• Sudden onset of pain is a hallmark of tissue damage, and may occur immediately or be delayed for several minutes or hours. • Involvement of the maxillary sinus will lead to acute sinusitis. • Associated bleeding into the interstitial tissues results in bruising and ecchymosis of the surrounding mucosa and possibly the facial skin and may include the formation of a hematoma. • A necrotic ulceration of the mucosa adjacent to the tooth may occur as a direct result of the chemical burn. • This reaction of the tissues may occur within minutes or may be delayed and appear some hours or days later.
• If these symptoms develop, urgent telephone referral should be made to the nearest maxillofacial unit. • Patients will be assessed by the on call maxillofacial team. • Treatment is determined by the extent and rapidity of the soft tissue swelling but may necessitate urgent hospitalization and administration of intravenous steroids and antibiotics. • Although the evidence for the use of antibiotics in these patients is anecdotal, secondary bacterial infection is a distinct possibility in areas of necrotic tissue and therefore they are often prescribed as part of the overall patient management. • Surgical drainage or debridement may also be required depending on the extent and character of the tissue swelling and necrosis.
2) Neurological complications - Paraesthesia and anaesthesia affecting the mental, inferior dental and infra-orbital branches of the trigeminal nerve following inadvertent extrusion of sodium hypochlorite beyond the root canals. - Normal sensation may take many months to completely resolve. - Facial nerve damage was first described by Witton et al. in 2005. - In both cases, the buccal branch of the facial nerve was affected. - Both patients exhibited a loss of the naso-labial groove and a down turning of the angle of the mouth. - Both patients were reviewed and their motor function was regained after several months. - Sensory and motor nerve deficit are not commonly associated with acute dental abscesses. - As there is no other current evidence in the literature it is possible that these neurological complications were a direct result of chemical damage by sodium hypochlorite, but further research (including nerve conduction studies) is required.
3) Upper airway obstruction The use of sodium hypochlorite for root canal irrigation without adequate isolation of the tooth can lead to leakage of the solution into the oral cavity and ingestion or inhalation by the patient. This could result in throat irritation and in severe cases, the upper airway could be compromised. Ziegler presented a case of a 15-month-old girl who presented in the accident and emergency unit with acute laryngotracheal bronchitis, stridor and profuse drooling from the mouth as a result of ingestion of a high concentration of household sodium hypochlorite. A similar clinical presentation might occur with the ingestion of any caustic substance. Opinion varies as to the best concentration of hypochlorite, with some practitioners using undiluted household bleach. Fibre optic nasal tracheal intubation followed by surgical decompression has been required to manage airway compromising swelling arising within three hours of accidental exposure to sodium hypochlorite during root canal treatment
Preventive measures that should be taken to minimize potential complications with sodium hypochlorite • Plastic bib to protect patient's clothing • Provision of protective eye-wear for both patient and operator • The use of a sealed rubber dam for isolation of the tooth under treatment • The use of side exit Luer-Lok needles for root canal irrigation • Irrigation needle a minimum of 2 mm short of the working length • Avoidance of wedging the needle into the root canal • Avoidance of excessive pressure during irrigation
Placement of rubber stop on irrigation needle • Needle must be side venting • Hypodermic (end exiting) needles in root canal irrigation risks accidental inoculation into the soft tissues. • Luer-Lok style syringes and needles should be used, as taper seat needles may dislodge in use, with uncontrolled loss of the hypochlorite solution under pressure. • Needle should not engage the sides of the canal, but be loosely positioned within the canal. • Needle should not reach the apical extent of the prepared canal. • This technique may be facilitated by marking the working length on the needle with a rubber stop. irrigant delivered slowly with minimal pressure to reduce the likelihood of forcing it through the apex. Achieved by using your index finger rather than thumb to depress the plunger. • This will reduce the risk to periapical tissues by inadvertent extrusion of irrigant.
Emergency management of accidental hypochlorite damage Eye injuries Irrigate gently with normal saline. If normal saline is insufficient or unavailable, tap water should be used Refer for ophthalmology opinion Skin injuries Wash thoroughly and gently with normal saline or tap water Oral mucosa injuries Copious rinsing with water Analgesia if required If visible tissue damage antibiotics to reduce risk of secondary infection If any possibility of ingestion or inhalation refer to emergency department Inoculation injuries Ice/cooling packs to swelling first 24 hours Heat packs subsequently Analgesia Antibiotics to reduce the risk of secondary infection Request advice or management from Maxillofacial Unit Arrange review if to be managed in dental practice
Effects of calcium hydroxide and sodium hypochlorite on the dissolution of necrotic porcine muscle tissue Gunna Hasselgren, Berit Olsson, Miomir Cvek JOE, Volume 14, Issue 3, March 1988, Pages 125–127 • The dissolving effect of the endodontic medicaments calcium hydroxide (Ca(OH)2) and sodium hypochlorite (NaOCI) on necrotic tissue was studied. • Pieces of necrotic porcine muscular tissue were placed in either a 0.5% NaOCI solution (Dakin's solution), Ca(OH)2, mixed with water, or a NaOCI solution following pretreatment in Ca(OH)2 for various time intervals. • The tissue pieces placed in 0.5% NaOCI were not completely dissolved after 12 days. When NaOCI solution was changed every 30 min, the tissue was completely dissolved after 3 h. • Pieces placed in Ca(OH)2 exhibited a marked swelling and a jelly-like consistency.
• The increase in weight was maintained for 24 h, after which a decrease was noted. • After 12 days, the tissue was completely dissolved. • Pretreatment with Ca(OH)2 for 30 min caused the tissue to dissolve in NaOCI within 90 min. Pieces that were pretreated for 24 h or 7 days dissolved within 60 min. • As a control, tissue pieces were kept in isotonic saline solution and these were not dissolved after 12 days. • Apparently, long-term treatment with Ca(OH)2 can dissolve necrotic tissue and pretreatment with Ca(OH)2 can enhance the tissue dissolving effect of NaOCl.
Tissue-dissolving capacity and antibacterial effect of buffered and unbuffered hypochlorite solutions Matthias Zehnder, Daniel Kosicki, Hansueli Luder, Beatrice Sener, Tuomas Waltimo Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and Endodontology Volume 94, Issue 6 , Pages 756-762, December 2002 • The goal of this study was to compare the dissolving potential of Dakin's solution with that of equivalent buffered and unbuffered sodium hypochlorite solutions on fresh and decayed tissues. In addition, the antimicrobial effect of Dakin's solution and equivalent unbuffered hypochlorite was tested. • Study Design. Tissue specimens were obtained from freshly dissected pig palates. Unbuffered 2.5% and 0.5% sodium hypochlorite solutions and 0.5% solutions buffered at a pH of 12 and a pH of 9 (Dakin's solution) were tested on fresh and decayed tissue. Tissue decay was assessed histologically. Antimicrobial testing was performed with Enterococcus faecalis in dentin blocks and on filter papers.
• Results • The 2.5% NaOCl solution was substantially more effective than the three 0.5% solutions in dissolving the test tissues. Buffering had little effect on tissue dissolution, and Dakin's solution was equally effective on decayed and fresh tissues. No differences were recorded for the antibacterial properties of Dakin's solution and an equivalent unbuffered hypochlorite solution. • Conclusions • In contrast to earlier statements, the results of this study do not demonstrate any benefit from buffering sodium hypochlorite with sodium bicarbonate according to Dakin's method. An irrigation solution with less dissolving potential may be obtained by simply diluting stock solutions of NaOCl with water.
CONCLUSION • New concepts usually are overrated in initial studies when compared to the gold standard. • Some recent approaches to improve root canal debridement include the use of laser light to induce lethal photosensitization on canal microbiota, irrigation using electrochemically activated water, and ozone gas infiltration into the endodontic system. • However, in terms of killing efficacy on endodontic microbiota in biofilms, there is good evidence that none of these approaches can match a simple sodium hypochlorite irrigation.
References- 1. Cohen’s PATHWAYS OF THE PULP- 10TH EDITION 2. Problem solving in Endodontics- fourth edition, GUTMANN, DUMSHA, LOVDAHL 3. Root Canal Irrigants , J Endod 2006;32:389–398 Matthias Zehnder 4. Review: the use of sodium hypochlorite in endodontics — potential complications and their management H. R. Spencer, V. Ike& P. A. Brennan:British Dental Journal 202, 555 - 559 (2007) 5. Tissue-dissolving capacity and antibacterial effect of buffered and unbuffered hypochlorite solutions Matthias Zehnder, Daniel Kosicki, Hansueli Luder, Beatrice Sener, Tuomas Waltimo OOOOE, Volume 94, Issue 6 , Pages 756-762, December 2002 6. Newer Root Canal Irrigants in Horizon: A Review, Sushma Jaju and Prashant P. Jaju International Journal of Dentistry, Volume 2011 (2011), Article ID 851359, 9 pages 7. G. Sundqvist, “Ecology of the root canal flora,” Journal of Endodontics, vol. 18, no. 9, pp. 427– 430, 1992
7. “The synergistic antimicrobial effect by mechanical agitation and two chlorhexidine preparations on biofilm bacteria,” Y. Shen, S. Stojicic, W. Qian, I. Olsen, and M. Haapasalo, Journal of Endodontics, vol. 36, no. 1, pp. 100–104, 2010. 8. “Endodontic irrigation,” T. D. Becker and G. W. Woollard, General Dentistry, vol. 49, no. 3, pp. 272–276, 2001. 9. * Yesilroy C, Whitaker E, Cleveland D, Philps E, Trope M: Antibacterial and toxic effects of established and potential root canal irrigants. J Endod 21:513, 1995