hypo chlorite in endodontics and conservative dentistry

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1. By Dr. V Krishnan PG, Dept of Cons ervative Dentistry & Endodontics SODIUM HYPOCHLORITE

2. CONTENTS Introduction Root canal bacterium Root canal irrigants Ideal requirements of a root canal irrigant History of NaOCl Chemistry of NaOCl Mode of action Suggested irrigation regimen Efficacy Time factor Interactions Accidents and management Conclusion References

3. INTRODUCTION

4. Main cause of endodontic failure- Microorganisms , either remaining in the root canal space after treatment or re-colonizing the filled canal system. Primary endodontic treatment goal- optimize root canal disinfection and to prevent re-infection . 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 all 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 effectiveness 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.

5. Root Canal Bacterium Primary root canal infections are polymicrobial, typically 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, Lactobacillus 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 Lactobacilli, 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.

6. Root Canal Irrigants It is generally 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. Ideally 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.

7. Ideal Requirement of Root Canal Irrigants It appears evident that root canal irrigants ideally should ha v e a b r o a d a nt i m icr ob i a l s pe c t r u m an d h i g h e f f ic a c y a g a i n s t a n a e r ob i c a n d 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, be systemically nontoxic, be non caustic to periodontal tissues, be little potential to cause an anaphylactic reaction.

8. A l a r g e n u m b e r o f s u b s t an c e s h a v e b ee n u s e d a s r o o t c ana l i r r i ga n t s , i n cl u d i n g a ci d s ( c i tr i c d i a mi n e t e t r a a c e t i c a c i d and E D T A ) , pho s pho r i c) , proteolytic c he l a ti n g enzymes, agent a l k a l i n e ( e t h y l en e s o l u ti o n s ( s o d i u m h y po c h l o r i t e , s od i u m h y d r o x i d e , u r e a , an d p o t a ss i u m h y d r o x i d e ) , p e r o xi d e and Gly-Oxide), local anesthetic o xi d a t i v e age n t s ( h yd r oge n solutions, and normal saline . T h e m os t w i d e l y u s e d en d odo n t i c i rri g a n t is . 5 % to h y p o c h l o r i t e (N a O C l ) , b e c a u s e o f i t s b a ct e r i ci da l a c ti v i t y 6.0% sodium an d ab il i t y to dissolve vital and necrotic organic tissue. H o we v e r , N a O C l s o l u t i on s e x e r t n o e f f ec t s o n i n o r ga n i c c o m pone n t s 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

9. Sod i u m hypochlorite i s t h e m o s t co m mon l y u se d t h e t h e endodontic irrigant, despite limitations. None of presently available root canal irrigants satisfy requirements of ideal root canal irrigant. Newer root canal i r r i ga n t s a r e s tud i e d f o r p o te n t i a l r ep l a ceme n t o f sod i u m hypochlorite. Newer Root Canal Irrigantsin Horizon: A Review Sushma Jaju and Prashant P. Jaju International Journal of Dentistry Volume2011 (2011), Article ID 851359, 9 pages doi:10.1155/2011/851359

10. Most commonly used irrigating solution Excellent 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, efficacy against pathogenic organisms and pulp digestion low viscosity allowing 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)

11. HISTORY Potassium hypochlorite was the first chemically produced aqueous chlorine solution, invented in France by Berthollet (1748-1822). Starting in the late 18th century, this solution was industrially 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 controlled laboratory studies by Koch and Pasteur , hypochlorite then gained wide acceptance as a disinfectant by the end of the 19th century.

12. 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 efficacy of different solutions on infected necrotic tissue. Beside their wide-spectrum, nonspecific killing efficacy on all 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 effective than hypochlorite at comparable concentration.

13. C H E M I S T R Y 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 following 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 - .

14. 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.

15. 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 ultrasonically 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. Ultrasonic energy may simply produce heat , thus rendering the hypochlorite slightly more active.

16. MODE OF ACTION In use for almost a century Possesses broad spectrum antimicrobial activity against endodontic microorganisms and biofilms, including microbiota difficult to eradicate from root canals such as Enterococcus, Actinomyces and Candida Dissolves organic material such as pulp tissue and collagen 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 universally 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.

17. 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, m odu l u s a n d a 5.25% solution significantly decreases the elastic flexural strength of human dentin compared to physiologic saline, while a 0.5% solution does not.

18. 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 suffice 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 physically 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 2 % wt/vol.

19. 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 filled with sodium hypochlorite’. This will increase the working time of the irrigant. In addition, cutting efficacy of hand instruments is improved and torsional load on rotary nickel-titanium instruments is reduced in fluid-filled environments compared to dry conditions. Submersing instruments for hours in a hypochlorite solution will induce corrosion. However, no adverse effects should be expected during the short contact periods when an instrument is manipulated in a root canal filled with hypochlorite.

20. 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 effective 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 called substantivity . ‘Substantivity is not observed with sodium hypochlorite.’

21. E FF I CA C Y - Waltimo et al- C. albcans was killed In Vitro in 30 secs by both 5% and 0.5%. Vianna et al – C. albcans was killed in 30 mins by 0.5% and in 15 secs by 5.25%. Gomes et al- E.faecalis was killed within 30secs by 5.25% and it required 10 and 20 mins for 2.5 and 0.5% solution. Siqueria et al- found no dfference in efficacy of 1, 2.5 and 5% in infected root canal. Experiments with Gram negative anaaerobic rods P.gingivalis , Porphyromonas endodontalis , P. intermedia demonstrated higher susceptiblity to NaOCl and were killed in 15 secs with 0.5% to 5% solution.

22. Infected dentin blocks- 0.25% sufficient to kill E.faecalis in 15 mins, conc of 1% requires 1 hr to kill Candida albicans * Ruff et al., in infected extracted teeth, found that 1 min application of 6% NaOCl and 2% chlorhexidine equally effective in eliminating microorganisms and statistically significantly superior to MTAD and 17% EDTA in eliminating Candida albicans infections

23. 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 small, files must carry the NaOCl to the apical third during instrumentation . 1% solution- effective, at dissolving tissue and providing an antimicrobial effect .

24. Increasing efficacy of hypochlorite preparations I n cre a sin g t e m pe r a t u r e o f l o w c on c e n t r a ti o n N a O C l s o l u ti o n s - w h i c h improve their immediate tissue-dissolution capacity. Heated hypochlorite solutions remove organic debris from dentin shavings more efficiently A n tim i c r obia l p r op e r ti e s o f h e a t e d N a O C l - b a c t e ric i da l r a t e s m o r e t h a n doubled for each 5 O rise in temperature in the range of 5-60 . Heating the solution Increasing pH of solution Increasing conc of the solution Ultrasonic activation

25. 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)

26. Warming of NaOCl to 50 o c or 60 o c increases collagen dissolution and disinfecting potential, but it may also have severely detrimental effects on NiTi instruments, causing corrosion of the metal surface after immersion for 1 hour Rotary instrument immersed for 2 hours in NaOCl heated to 60 o c, showing severe corrosion

27. A study using steady state planktonic E.fecalis cells, showed a temperature rise of 25 o c increased NaOCl efficacy by a factor of 100. Capacity to dissolve human dental pulp using 1% NaOCl at 45 o c was found to be equal to that of a 5.25% solution at 20 o c. Systemic toxicity of preheated low conc of NaOCl irrigants should be less than that of a more concentrated unheated solution.

28. 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, 10 th edition

29. 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).

30. 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)

31. Discolouration when irrigants are combined. 2.63% NaOCl + 2% chlorhexidine (CHX) (dark brown precipitate); 18% EDTA + 2% CHX (cloudy blue); 2.63% NaOCl + 18% EDTA (no discolouration) d) 2.63% NaOCl + 20% Citric acid (white precipitate and the solution turns cloudy after shaking).

32. This dark brown precipitate can stain the dentine, adhere to the floor of the pulp chamber, access cavity and root canal walls 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. NaOCl Dark brown precipitate after NaOCl/CHX combination The precipitate becomes adherent to the access cavity walls (white arrow) and crown fissures (red arrow) even after flushing with distilled water.

33. 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).

34. 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.

35. 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).

36. 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.

37. 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)

38. 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).

39. 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 efficacy .

40. The allergic potential of sodium hypochlorite was first reported in 1940 by Sulzberger and subsequently by Cohen and Burns . S odium 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)

41. To avoid extrusion an d s e r i ou s d a m ag e t o p e r i ap i ca l shou l d neve r be w edge d into canals t i s sues , d u r i n g irri ga t i o n n e ed l e s irrigation. H i ghe r con c en t r a t i o n N a O Cl - m o r e a gg r ess i v e t o w a r d li v i n g t i ssu e and can cause severe injuries when forced into periapical area. 27 gauge needle 30 gauge side venting needle

42. Toxic effect of sodium hypochlorite on periradicular tissues. After root canal treatment of the first molar, the patient reported pain On a return visit, an abscess was diagnosed and incised. Osteonecrosis was evident after 3 weeks.

43. 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, allowing 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 capillary effect. Patency files should not be extended farther than the periodontal ligament because they are possible sources of irrigant extrusion

44. Complications of accidental spillage Damage to clothing Accidental spillage 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. 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.

45. 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 . 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 . The use of adequate eye protection during endodontic treatment should eliminate the risk of occurrence of this accident. It has been advised that eyes exposed to undiluted bleach should be irrigated for 15 minutes with normal saline.

46. 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)

47. 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 . 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 .

48. Bruising and oedema of patients who presented with hypochlorite extrusion into the soft tissues

49. 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.

50. 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.

51. 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. .

52. 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 . 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

53. 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 Preventive measures that should be taken to minimize potential complications with sodium hypochlorite

54. 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 . 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 .

55. 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 Emergency management of accidental hypochlorite damage

56. C O N C L U S I O N 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.

57. References- Cohen’s PATHWAYS OF THE PULP - 10 TH EDITION Problem solving in Endodontics - fourth edition, GUTMANN, DUMSHA, LOVDAHL Root Canal Irrigants , J Endod 2006;32:389–398 Matthias Zehnder 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) 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 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 G. Sundqvist, “ Ecology of the root canal flora ,” Journal of Endodontics, vol. 18, no. 9, pp. 427– 430, 1992

58. 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