Sodium Hypochlorite Dental Emergency-A Review

Root canal irrigants play an important role in the success of root canal treatment. As the major objective in root canal treatment is to disinfect the entire root canal system, it requires that the pulpal contents be eliminated as sources of infection. This goal may be accomplished using mechanical instrumentation and chemical irrigation, in conjunction with medication of the root canal between treatment sessions. However there remains a risk of extrusion of these irrigants beyond or into the surrounding tissues and cause severe complications. Sodium hypochlorite is widely used in dental practice during root canal treatment. Although generally regarded as being highly effective as an irrigant, potentially severe complications occur when it comes in contact with soft tissues. This article discusses the use, inadvertent effects of sodium hypochlorite and considers the appropriate management for a practitioner when faced with potential adverse incident with this agent.


Introduction
Endodontic emergency is a condition associated with pain, swelling which require immediate diagnosis and treatment. The main causative factors responsible for the occurrence of endodontic emergencies are mainly pulp and periradicularpathosis, traumatic injuries, procedural complications etc, among which sodium hypochlorite accidents can occur.
Success of root canal treatment relies on thorough debridement and shaping of canals. It is well documented that the impetus behind root canal cleaning and shaping is the elimination of tissue remnants, bacteria and toxins from root canal system. Mechanical preparations alone are insufficient for total canal cleaning [1]. If instrumentation were 100% effective in removing all bacteria and debris from canal, irrigation would be an insignificant factor to mechanical debridement. Unfortunately this is not the case. There are many studies that show the limited ability of instrumentation alone to debride and clean the canal [2][3][4][5][6]. Wu and Wesselink reported uninstrumented areas in 65% of instrumented oval canals [7]. The complete shaping and debridement of root canals is often difficult because of the morphology of the canals. Therefore, irrigating solutions should support and compliment endodontic preparation. The irrigants used should flush out dentin debris, dissolve organic tissue, disinfect the canal, and provide lubrication effect during instrumentation without irritating the surrounding tissues. Some of the irrigants used include hydrogen peroxide,chlorhexidine, saline, among which sodium hypochlorite more commonly used. Sodium hypochlorite is used as an irrigant because of its effective antimicrobial and tissue dissolving capabilities. A variety of sodium hypochlorite concentrations ranging from 0.5%-5.2% have been advocated. Generally the solution is applied to the canals during and after mechanical preparation. The effective concentration range of sodium hypochlorite is from 2.6 to 5.25% [8,9].

Advantages
• Due to the high pH ,the hydroxyl ions alters the integrity of cytoplasmic membrane of microorganisms, causes irreversible enzymatic inhibition, biosynthetic alterations in cellular metabolism and phospholipid degradation by liquid peroxidation.
• Strong dissolving action in the presence of organic tissue and microorganisms, by breaking down of proteins into aminoacids (Table 3) • Haemostaticproperty (Table 4).

Disadvantages
The negative property or drawback of sodium hypochlorite is, it can cause soft tissue inflammation if expressed outside the confines of root canals [27]. Acute inflammation followed by necrosis results when sodium hypochlorite comes into contact with vital tissue. It causes

Author
Year Findings Sen et al. [10] 1999 Evaluated antifungal properties of 1% NaOCl, and 5% NaOCl and 0.12 % CHx against candida albicans using cylindrical dentin tubes, and found that in absence of smear layer, candida albicans display antifungal activity after 30 minutes.
Ferguson et al. [11] 2002 Determined in-vitro susceptibility of candida albicans to various irrigants and medicaments, and found out that NaOCl , hydrogen peroxide were effective against candida albicans even when diluted.
Marcia et al.

2009
Evaluated the action of NaOCl associated with an intracanal medicament against candida albicans and E.faecalis and found that 1% NaOCl irrigation were effective in eliminating E.faecalis and candida albicans.
Ruff et al. [12] 2006 Found that 6 % NaOCl was equally effective and statistically superior to Biopure MTAD and 17 % EDTA in antifungal activity  Open Access 2 severe inflammation and cellular destruction in all tissues except heavily keratinized epithelium [28]. The severity of the complication depends on the concentration of solution, its pH and its duration of exposure. Sodium hypochlorite has a pH of 11-12.5 which causes injury by oxidation of proteins. Higher concentrations have some irritating effects on the periodontal ligament [29].
This article reviews the potential complications that can occur with sodium hypochlorite in clinical practice, discusses the measures that can be taken to minimize the risk and provides details to appropriate management in rare cases of suspected tissue damage.

Toxicity of Sodium Hypochlorite
Sodium hypochlorite when comes in contact with tissue proteins, forms nitrogen, formaldehyde and acetaldehyde in short time and peptide links are broken resulting in dissolution of proteins. During the process, hydrogen in the amino groups is replaced by chlorine thereby forming chloramines which plays an important role in antimicrobial effectiveness. Necrotic tissues are thus dissolved and microbial agent can reach and clean the infected areas better. Pashley et al. [27] demonstrated the cytotoxicity of Sodium hypochlorite using three independent biological models. They found that a concentration as low as 1:1000 (v/v) Sodium hypochlorite in saline caused complete haemolysis of red blood cells in vitro. As the solution used in this study was isotonic and thus excluded an osmotic pressure gradient, the observed haemolysis and loss of cellular protein was due to the oxidizing effects of Sodium hypochlorite on the cell membrane. Undiluted and 1:10 (v/v) dilutions produced moderate to severe irritation of rabbit eyes whilst intradermal injections of undiluted, 1:2, 1:4 and 1:10 (v/v) dilutions of Sodium hypochlorite caused skin ulcers. Kozol et al. [30] proved Dakin's solution to be detrimental to neutrophil chemotaxis and toxic to fibroblasts and endothelial cells.
Heggers et al. [31] examined wound healing relative to irrigation and bactericidal properties of Sodium hypochlorite in vitro and In vivo models. They concluded that 0.025%Sodium hypochlorite was the safest concentration to use because it was bactericidal but not tissue-toxic. Zhang et al. [32] evaluated the cytotoxicity of four concentrations of Sodium hypochlorite (5.25%, 2.63%, 1.31%, and 0.66%), eugenol, 3% H 2 O 2 , Ca(OH) 2 paste and MTAD results showed that toxicity of Sodium hypochlorite was dose-dependent. Barnhart et al. [33] measured the cytotoxicity of several endodontic agents on cultured gingival fibroblast using the CyQuant assay. The results showed that IKI and Ca(OH) 2 were significantly less cytotoxic than Sodium hypochlorite. Most complications of the use of sodium hypochlorite appear to be the result of its accidental injection beyond the root apex which can cause violent tissue reactions characterized by pain, swelling, haemorrhage, and in some cases the development of secondary infection and paresthesia [34]. A great deal of care should therefore be exercised when using sodium hypochlorite during endodontic irrigation. Ehrich et al. [35] suggested that a clinician should check, both clinically and radiographically for immature apices, root resorption, apical perforations or any other conditions that may result in larger than normal volumes of irrigant being extruded from the root-canal system into the surrounding tissue. Irrigation should be performed slowly with gentle movement of the needle to ensure that it is not binding in the canal. In an in vitro study by Brown et al. [36], the use of a reservoir of irrigation fluid in the coronal access cavity and carried into the root canal during filing resulted in significantly less apical extrusion of irrigation solution than with deep delivery with an irrigation needle.

Complication during Irrigation
During root canal irrigation, accidental extrusions can occur. Even minute quantities if extruded cause vascular probabilities in blood vessels due to the damage to the vessels as well as release of chemical mediators
Clegg et al. [15] 2006 Evaluated effectiveness of three concentrations of NaOCl (6,3,1.5%),2% CHX and biopure MTAD on apical denti film in vitro and found out 6% NaOCl was only capable of both rendering bacteria nonviable and physically remove the biofilm Ozok et al. [16] 2007 Compared growth and susceptibility of different concentrationsofNaOCl of mono and dual species biofilms of fusobacteriumnucleatum in-vitro at 24 hrs and found out at 243hrs they were more resistant to NaOCl.

Giardino et al. [17] 2007
Evaluated efficiency of 5.25% NaOCl and MTAD against E.Faecalis biofilm and found that only 5.25% NaOCl can disgregate and biofilm every time.

Moorer et al. [19] 2003
Tissue dissolution was dependent on 3 factors-frequency of agitation, amount of organic matter in relation to amount of irrigant in system and surface area of tissue.
Clarkson et al. [22] 2006 Evaluated tissue dissolution ability of two concentrations of NaOCl on porcine incisor pulp and found greater concentrations provide more dissolution of tissue.

Marcus et al. 2011
Evaluated the tissue dissolving capacity of various concentrations of NaOCl either alone or in combination of 17%EDTA and found that dissolution property was more with NaOCl alone.

Author Year Findings
Hafez et al. [24] 2002 Showed that 3% NaOCl was biocompatible as a haemostatic control agent Murina et al. [25] 1986 Showed that concentrations higher than 1mm, suppresses ADP dependent aggregations of blood platelets.
Murina et al. [26] 2006 Showed that anti-aggregant effects of NaOCl are probably due to the oxidation modification of sulphur containing groups in platelet plasmatic membrane. Open Access 3 such as histamine for the involved tissue. This causes immediate swelling and often profuse bleeding through the root canal.

Forschen Sci
In a case report, after wedging the irrigating needle into the root canal, 2.5% sodium hypochlorite was extruded beyond the apex of maxillary left central incisor. The patient experienced severe pain during irrigation of root canal system so the root canal preparation was discontinued immediately and temporary dressing given. 3 hrs later, the patient came back to clinic with an extended odema and ecchymosis over the left side of face, infraorbital region and upper lip mucosa. After removing the temporary filling, heavy bleeding from the canal was observed. The canal was biomechanically prepared by hand files with sterile saline solution irrigation. Antibiotics were prescribed against secondary infection and analgesics were also administered for pain control. Cold compress, warm mouth rinses was also advised on the first day. On the third day, pain and ecchymosis was reduced. By the 10 th day, no bleeding, pain, or ecchymosis was observed. By the 20 th day root canal obturation was performed.
Reeh and Messer reported on a case of injection of sodium hypochlorite (1%) through a mid root perforation of a maxillary central incisor. The patient experienced the typical symptoms of immediate severe pain and swelling, followed by fistulation and erythema extending to the infraorbital area. Paraesthesia of the floor and ala of the patient's nose persisted for more than 15 months. In a case report presented by Sabala and Powell 5.25% sodium hypochlorite was injected into the Periapical tissues of a left maxillary second premolar. The patient experienced symptoms of sudden, severe pain and a swelling rapidly developed, followed by ecchymosis of the skin. Root canal treatment was completed at the same appointment. To prevent secondary infection, antibiotics were prescribed and a surgical drainage performed. Nine days later the symptoms had resolved. Management (Table 5) • Immediate irrigation of canal with normal saline to dilute the sodium hypochlorite. • Let the bleeding response continue to flush the irritant out.

Signs and symptoms
• Advice ice pack compression for 24 hours (15 minutes interval) to minimize the swelling.

Conclusion
Sodium hypochlorite, being an effective antibacterial agent, can also be highly irritating when extruded or when it comes in contact with vital tissues. Most of the reported complications occurred due to the errors the different steps in root canal treatment. In summary, this review discusses the advantages, disadvantages, potential complications, prevention and management of sodium hypochlorite accidents in endodontic dental practice. Although very rare, the correct recognition and immediate primary management is essential to ensure best long lasting safe clinical practice. Patient with NaOCl extrusion followed endodontic treatment in maxillary first molar with excruciating pain, with blood stained fluid from left nostril; all managed by first ENT consultant for nasoscopy and then later root canal treatment completed.

Jonathan et al. 2015
A patient with NaOCl extrusion followed perforation during rootcanal treatment in maxillary first premolar with swelling, bruising; pain was managed by i.v antibiotics, analgesics, steroids and then surgical intervention and finally full recovery was observed.

Bernardo et al. 2014
A patient with NaOCl apical extrusion followed rootcanal returned in 24 hours with extreme pain, burning sensation in maxillary region with oedema and was managed by amoxicillin 500 mg orally for 7 days then dexamethasone 4 mg I.M. for 3days. Symptoms subsided after 8 months.