Sodium Hypochlorite in Endodontics

8/18/2019 Sodium Hypochlorite in Endodontics

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Guided by:

Dr

Pratima

R

Shenoi

Dr

Deepa

Shori

Dr. Rajesh

Kubde

Presented by:

Dr Vishal Dhande


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Contents Introduction Natural occurrence

History of chlorine releasing agents

Production Chemistry

Mechanism of action

Antimicrobial properties

Effect on biofilms

Ability to dissolve organic tissue

Alkaline nature of solution


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Surface tension

Buffering effect of dentin on NaOCl

Effect of NaOCl on dentin

Effect of NaOCl on bonding to dentin

Toxicity of NaOCl Hemostatic property

Effect of NaOCl on endodontic instruments

Increasing efficacy of NaOCl

Interactions with other irrigants Allergic reactions

Complications


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Introduction

Eliminationof micro-organisms

Successfulendodontictreatment


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Natural occurrence Chlorine is one of the most widely distributed

elements on earth.

It is not found in a free state in nature, butexists in combination with sodium, potassium,calcium, and magnesium.

Dychdala GR. Chlorine and chlorine compounds. In: Block SS, ed.

Disinfection, sterilization and preservation. Philadelphia: Lea & Febiger,

1991:131 –

51.


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In the human body, chlorine compounds arepart of the nonspecific immune defense.

They are generated by neutrophils via themyeloperoxidase-mediated chlorination of anitrogenous compound or set of compounds

Test ST,. J Clin Invest 1984;74:1341 –

9.


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History of Chlorine-Releasing Agents

Potassium hypochlorite was the firstchemically produced aqueouschlorine solution, invented in Franceby Berthollet (1748-1822).

This solution was industrially produced by Percy in Javelle near

Paris, hence the name “Eau de Javel”.

First, hypochlorite solutions wereused as bleaching agents.


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Sodium hypochlorite was recommended by Labarraque (1777-1850) to prevent childbed fever andother infectious diseases.

In World War I, the chemistHenry Drysdale Dakin andthe surgeon Alexis Carrelextended the use of a

buffered 0.5% sodiumhypochlorite solution to theirrigation of infected

wounds.


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These features prompted the use of aqueous sodiumhypochlorite in endodontics as the main irrigant asearly as 1919 as recommended by Coolidge.

Walker, in 1936, introduced the use of double-strength chlorinated soda (5% NaOCl) solution as aroot canal irrigant in endodontic practice.

Non-specific killing effects on all microbes

Sporicidal

ViricidalGreater tissue dissolving effects on necrotic than on vital tissues


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Other chlorine-releasing compounds have beenadvocated in endodontics, such as chloramine-T

and sodium dichloroisocyanurate

These, however, have never gained wideacceptance in endodontics, and appear to be less

effective than hypochlorite at comparableconcentration.


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Production Sodium hypochlorite has traditionally

been produced by bubbling chlorinegas through a solution of sodiumhydroxide (NaOH), to produce sodiumhypochlorite (NaOCl), salt (NaCl) and

water (H2O).

Cl2 + 2NaOH –> NaOCl + NaCl + H2O


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It uses electrolysis of a saturated brine solution toproduce sodium and chloride ions.

The sodium ions diffuse through a membrane, wherethey combine with water to produce sodiumhydroxide.

The chloride ions from the first compartmentcombine to give chlorine gas which is dissolved in thesodium hydroxide to give sodium hypochlorite, saltand water.

Alternative method for production –


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PropertiesCommercial sodium hypochlorite solutions are

An oxidizing and hydrolyzing agent.

Bactericidal and Proteolytic

Strongly alkaline

Hypertonic

Typically have nominal concentrations of 10 to 14 percent available chlorine.

They deteriorate with time, temperature, exposure to

light, and contamination with metallic ions.


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Chemistry

Sodium hypochlorite exhibits a dynamic balance as isshown by the reaction:

NaOCl + H2O NaOH + HOCl- Na+ + OH- + H+ + OCl-

Reactive chlorine in aqueous solution at bodytemperature can, in essence, take two forms:

Hypochlorite (OCl) or Hypochlorous acid (HOCl).

Pecora JD, Artes Médicas; 1999. p. 552-69.


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1 mol of hypochlorite contains 1 mol of availablechlorine.

The state of available chlorine is depending on thepH of the solution.


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Above a pH of 7.6, the predominant form is

hypochlorite, below this value it is hypochlorousacid.


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Both forms are extremely reactive oxidizing agents.

Pure hypochlorite solutions as they are used inendodontics have a pH of 12, and thus the entireavailable chlorine is in the form of OCl-.


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Hypochlorous acid is responsible for theantibacterial activity; the OCl ion is less effective

than the undissolved HOCl.

Hypochloric acid disrupts several vital functionsof the microbial cell, resulting in cell death.


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Saponification reaction.

O O|| ||

R – C – O – R + NaOH R – C – O – Na + R – OH

Fatty acid Sodium Soap Glycerol

hydroxide

Mechanism of action


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. Amino acid neutralization reaction

H O H O

| // | //

R – C – O – C + NaOH R – C – O – C + H2O

| |NH2 OH NH2 ONa

Amino acid Sodium Salt Water

Hydroxide


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Chloramination reaction.H O Cl O

| // | //

R–

C–

O–

C + HOCl R–

C–

O–

C + H2O| |

NH2 OH NH2 OH

Amino acid Hypochlorous Chloramine Wateracid


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Antimicrobial properties

The antimicrobial effectiveness of sodiumhypochlorite, based in its high pH.

The high pH of sodium hypochlorite interferes in thecytoplasmic membrane integrity with an irreversibleenzymatic inhibition, biosynthetic alterations in

cellular metabolism and phospholipid degradationobserved in lipidic peroxidation.


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The antibacterial effectiveness and tissuedissolution capacity of aqueous hypochlorite is afunction of its concentration.

The reduction of intracanal microbiota, on theother hand, is not any greater when 5% sodium

hypochlorite is used as an irrigant as compared to0.5%.


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All concentrations proved effective against

Candida albicans and Actinomyces naeslundii inless than 10 s.

But against Enterococcus faecalis — which is aspecies more resistant to NaOCl — there was a

variation in cells inactivation time: 0.5% concentration took 30 minutes;

1%, took 10 minutes;

2.5%, 5 minutes; and

5.25%, 2 minutes to reduce the number of viablecells to zero.

Radcliffe CEL Int Endod J. 2004;37(7):438-46.


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It has been shown that NaOCl kills the target

microorganisms rapidly even at low concentrationsof less than 0.1%.

However, in vivo the presence of organic matter(inflammatory exudate, tissue remnants,microbial biomass) consumes NaOCl and weakensits effect.

Therefore, continuous irrigation and time areimportant factors for the effectiveness of

hypochlorite.


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It must be realized that during irrigation, freshhypochlorite consistently reaches the canal system,and concentration of the solution may thus not play adecisive role.

Unclean areas may be a result of the inability of

solutions to physically reach these areas rather thantheir concentration.


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Effect on biofilms

Microbial communities grown in biofilms areremarkably difficult to eradicate with anti-microbial agents and microorganisms in maturebiofilms can be notoriously resistant.


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In case of root canal isolates including P. intermedia,Peptostreptococcus miros, Streptococcus intermedius,F. nucleatum, E. faecalis. NaOCl was the only irrigant

capable of both rendering bacteria nonviable andphysically removing the biofilm.


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Ability to dissolve organic tissue The ability of NaOCl to dissolve organic tissues is

directly proportional to its concentration.

The pulp dissolution time with different NaOClconcentrations (0.5%, 1%, 2.5% and 5.25%) rangedfrom 20 minutes to 2 hours.

Milano NFRev Fac Odontol Porto Alegre. 1991;32(1):7-10.


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The higher concentrations of NaOCl were morerapid on dissolution of the pulp tissue, and showedlower decrease in chlorine concentration.

1% NaOCl solution should suffice to dissolve theentire pulp tissue in the course of an endodontic

treatment session.


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Efficacy of the solvent and disinfectant action of

NaOCl solutions at low concentrations can beincreased by using higher volume of solution andfrequent exchanges.

The solvent capacity is directly proportional totemperature, in other words, the higher the

temperature of NaOCl solution the greater is itssolvent ability.


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An increased killing effect of heated solutionsagainst endodontic microbiota appears to bepresent not only with NaOCl but also with otherantiseptic irrigants such as chlorhexidinegluconate.


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Alkaline nature of the solution

The alkaline content of NaOCl is proportional toits concentration.

The higher the concentration, the higher the pH,

since it has greater amount of NaOH molecules.

The NaOCl with higher pH is more stable and

presents slower chlorine release. When the pH isreduced, the solution becomes very unstable andthe chlorine release is faster, resulting in a lowerlife cycle.


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Surface tension NaOCl presents a relative high surface tension (48.90

mJ/m2 ), limiting the solution penetration into canal

irregularities and deeply into the dentinal tubules


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Its efficiency can be improved by reducing its surfacetension because wettability of such solutions is ofprimary importance in extending its protein solvent

capability or perform the bactericidal functionthrough penetration into the un-instrumented areas ofthe root canal system.


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Surface tension might be reduced by using heat oradding chemicals known as surfactants.

The effect of the surface active agent to hypochlorite was first shown by Cameron who showed that theaddition of the surface modifiers enhanced the abilityof sodium hypochlorite to dissolve organic material.


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Clarkson et al tested the dissolution ability of threedifferent brands of sodium hypochlorite available in Australia and reported that the products with

surfactants dissolved porcine pulp in a shorter timethan regular sodium hypochlorite at the sameconcentration.


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Buffering effect of dentine on NaOCl

Wang and Hume showed that dentine was a strongbuffer against acids. Buffering against alkali (NaOH) was weaker but nevertheless considerable.

Inorganic apatites are supposed to be mainly

responsible for the buffering effect of dentine.


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Type I collagen and glycosaminoglycan lost theirimmunoreactivity after NaOCl treatment

However, in intact dentine this effect was minimal,suggesting that hydroxyapatite has a protective role by

embedding collagen and other proteins against theoxidative activity of NaOCl.


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Dentine has an inhibitory effect on the antibacterialeffectiveness of 1% sodium hypochlorite.

Haapasalo HK, Siren EK, Waltimo TM. Int Endod J 2000 33: 126-131.


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Effect of NaOCl on the dentine Dentine is composed of approximately 22% organic

material by weight.

Most of this consists of type I collagen, whichcontributes considerably to the mechanicalproperties of dentine.

Sodium hypochlorite solutions may affect themechanical properties of dentine by the degradationof organic dentine components.

Marending MInt

Endod J

2007 40: 786-793.


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Decrease in microhardness was more marked afterirrigation with 6% NaOCl than 2.5% NaOCl.

A 2hr exposure of dentine to NaOCl solutions ofmore than 3% (w/v) significantly decreases the

elastic modulus and flexural strength of humandentine compared to physiological saline.

Slutzky-Goldberg I, J Endod 2004 30: 880-882.

Sim TP. Int Endod J 2001 34: 120-132.


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5% NaOCl induced alterations in dentine collagen andglycosaminoglycans and hydroxyapatite demonstrateda protective role of on organic matrix stability.

Oyarzun A J Endod 2002 28: 152-156.


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Effect of NaOCl on bonding to dentine

Dentine is degenerated by NaOCl treatmentbecause of the dissolution of dentinal collagen.

Moreover, residual NaOCl may interfere withpolymerization of bonding resin due to oxygengeneration.


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Increase in the NaOCl application time resulted ina progressive decrease in shear bond strengths fordentine adhesives.

The decreased bond strength is improved when anascorbic acid or a sodium thiosulfate solution is

applied after NaOCl treatment. These solutionsremove NaOCl by the oxidation-reductionreaction.


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Haemostatic property

NaOCl is biologically compatible with exposed pulptissues and highly successful when used as ahaemostatic agent in direct pulp capping.

3% NaOCl was biocompatible as a haemorrhagecontrol agent, because pulps treated with thisconcentration demonstrated no evidence of pulpalnecrosis after 7- and 27-days.

Hafez AA, Kopel HM Quintessence Int 2000 31: 579-589.

Hafez AA Quintessence Int 2002 33: 261-272.


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Toxicity of NaOCl NaOCl is highly toxic at high concentrations and

tends to induce tissue irritation on contact.

Dakin’s solution to be detrimental to neutrophilchemotaxis and toxic to fibroblasts and endothelialcells.

Hauman CH, Love RM Int Endod J 2003 36: 75-85.


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0.025% NaOCl was the safest concentration to usebecause it was bactericidal but not tissue-toxic.

Severity of NaOCl cytotoxicity depends on the solutionconcentration, pH and duration of tissue exposure to

the agent.

Heggers JP. J Burn Care Rehabil 1991 12: 420 –

424.

Zhang W J Endod 2003 29: 654-657.


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Effects on endodontic instruments NaOCl is corrosive to metals involving selective

removal of nickel from the surface creating micro-pitting.

It is supposed that these microstructural defects canlead to areas of stress concentration and crack

formation, weakening the structure of theinstrument.


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Corrosion of endodontic files caused by NaOClsolutions of different concentrations from 0.5% to5.5%.

However the quantities of ions released by thecorrosion process into the NaOCl solutions were

insignificant.

Exposure to 5.25% NaOCl solution affects neitherresistance to flexural fatigue nor torsional resistanceof NiTi K3 endodontic files.

Busslinger BS, Barbakow F. Int Endod J 1998;31:2904.

Barbosa FO,. J Endod 2007;33:982-5.


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Interactions with other irrigantsEDTA –

Sodium Hypochlorite and EDTA are the most

commonly used irrigating solutions.

However, EDTA instantaneously reduces the

amount of chlorine when mixed with sodiumhypochlorite, resulting in the loss of NaOClactivity. Thus, these solutions should not be mixed

Zehnder M. J Endod 2005;31:817 –

20.


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Chlorhexidine CHX and NaOCl are not soluble in each other; a

brownish-orange precipitate is formed when theyare mixed.


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The precipitate is an insoluble neutral salt formedby the acid-base reaction between NaOCl andCHX.

Precipitate contains iron, which may be thereason for the orange development.

Presence of parachloroaniline, which may havemutagenic potential, has also been demonstratedin the precipitate.

Basrani BR. J Endod 2007;33:966 –9.


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Alexidine (ALX) The association of ALX/NaOCl did not produce

PCA or any precipitate, but resulted in a slightdiscolouration ranging from light yellow totransparent as the ALX concentration decreased.

In addition, this combination did not stain dentineand was easy to remove from the root canal by irrigation.

KIM HS , J Endod 2012 Jan;38(1):112-6


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MTAD Brown discoloration – when NaOCl used as final

rinse after MTAD

May be caused by the dentinal absorption and

release of the doxycycline, present in MTAD.

Formation of yellow precipitate - when NaOCl was used as an irrigant and then followed by theapplication of BioPure MTAD as a final rinse.

Torabinejad M Journal of Endodontics 29, 233–9.

Tay FR (2006a) Journal of Endodontics 32, 354–8.


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The chemical reaction between NaOCl and citricacid, which leads to the formation of a whiteprecipitate, indicates a complex interactionbetween NaOCl and MTAD


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Hydrogen peroxide When used in combination with NaOCl, bubbling

will occur as a result of nascent oxygen beingreleased through the chemical reaction betweenthese two liquids.

Despite more vigorous bubbling, the effectivenessof the mixture has not been shown to be betterthan that of NaOCl alone.


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Increasing efficacy of NaOCl

Baker gave the relationship between HOCl, OCl−,

and pH.

At pH 10, basically all chlorine is in the OCl− form;

the reverse occurs at a pH of 4.5, when all chlorineis in the form of HOCl.

By lowering the pH of the solution –

Baker RJJ Am Water Works Assoc 1959;51:1185-90.


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Sodium hypochlorites at a lower pH possess greaterantimicrobial activity.

HOCl was responsible for the destruction of microorganisms.

OCl− ion possesses approximately 1/80th of the germicidalpotency of HOCl in killing Escherechia coli.

Bloomfield SF Microbios 1979;10:33-43.

Andrews FWZentralbl Bakteriol Orig A 1904;35:645-51, 811-5.

Morris JC. J Am Water Works Assoc 1966;58:1475-82.


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This improves their immediatetissue-dissolution capacity.

Heated hypochlorite solutionsremove organic debris fromdentin shavings more efficiently than unheated counterparts.

By increasing the temp. of the solution –


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At the concentration of 1% and at 45°C, this substance

dissolved pulp tissue with the same efficiency than the5.25% at 20°C.

At 60°C the 1% NaOCl was more effective than the 5.25%at 20°C.


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A temperature raise of 25°C increased NaOClefficacy by a factor 100.

Bactericidal rates for sodium hypochloritesolutions are more than doubled for each 5°C risein temperature in the range of 5 to 60°C


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Ultrasonic activation -

This would “accelerate chemical reactions, createcavitational effects, and achieve a superiorcleansing action”


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Allergic reactions The allergic potential of sodium hypochlorite was first

reported in 1940 by Sulzberger and subsequently byCohen and Burns.

Real allergies to NaOCl are unlikely to occur, since bothsodium and chlorine are essential elements in thephysiology of the human body.

Hypersensitivity and contact dermatitis may occur inrare cases.

Sulzberger M B. Springfi eld, IL, USA: Charles C. Thomas, 1940.


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The usefulness of allergy skin scratch test insuspected cases of sodium hypochlorite allergy during endodontic treatment has been confirmedby Kaufman and Keila.

Kaufman A Y, Keila S. J Endod 1989; 15: 224-226.


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In cases of hypersensitivity to NaOCl, chlorhexidine

should not be used either (because of its chlorinecontent).

Use of an alternative irrigant with highantimicrobial efficacy, such as iodine potassiumiodide, should be considered.

Ca(OH)2 could be used as a temporary medicamentbecause it dissolves both vital and necrotic tissue.


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Complications

Damage to clothing-

As sodium hypochlorite is a common householdbleaching agent, even small amounts may cause

severe damage.

Prevented by

Proper protection of the patient’s clothing. Secure attachment of irrigation needle and syringe

to avoid leakage


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Damage to the eye Seemingly mild burns with an alkali such as

sodium hypochlorite can result in significantinjury as the alkali reacts with the lipid in the

corneal epithelial cells, forming a soap bubble thatpenetrates the corneal stroma.

Further degeneration of the tissues within theanterior chamber results in perforation, withendophthalmitis and subsequent loss of the eye.


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Symptoms associated Instant severe pain and intense burning.

Profuse watering (epiphora)

Erythema

Loss of epithelial cells in the outer corneal layer mayoccur.

Blurring of vision and patchy colouration of thecornea.


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It has been advised that eyes exposed to undilutedbleach should be irrigated for 15 minutes with a litre of normal saline.

Immediate ocular irrigation with a large amount of water or sterile saline is required followed by an urgentreferral to an ophthalmologist.

The use of adequate eye protection during endodontictreatment should eliminate the risk of occurrence of this accident

Rutala W Clinical Microbiology Reviews 1997; 10: 597-610.


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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 hydroxylions deep into the tissue, thereby limiting theircontact with the water dilutant on the skin surface.


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Water is the agent of choice for irrigating skin and itshould be delivered at low pressure as high pressuremay spread the hypochlorite into the patient's orrescuer's eyes.


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Damage to oral mucosa

Surface injury is caused by

the reaction of alkali with

protein and fats.

Swallowing of sodium hypochlorite requires thepatient to be monitored following immediatetreatment.

It is worth noting that skin damage can result

from secondary contamination.


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Additionally, extreme pressure during irrigation orbinding of the irrigation needle tip in the root canal with no release for the irrigant to leave the root canal

coronally may result in contact of large volumes of theirrigant to the apical tissues.


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Chemical burns and tissue necrosis

A severe acute inflammatory reaction of the tissues develops.

This leads to rapid tissue swellingboth intra orally within thesurrounding mucosa and extra

orally within the skin andsubcutaneous tissues.


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Sudden onset of pain is a hallmarkof tissue damage.

Associated bleeding into theinterstitial tissues results in

bruising and ecchymosis of thesurrounding mucosa and possiblythe facial skin and may include theformation of a hematoma.


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Treatment is determined by the extent and

rapidity of the soft tissue swelling but may necessitate urgent hospitalization andadministration of intravenous steroids andantibiotics.

Secondary bacterial infection is a distinct

possibility in areas of necrotic tissue and thereforeantibiotics are often prescribed as part of theoverall patient management.


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Neurological complications Paraesthesia and anaesthesia affecting the mental,

inferior dental and infraorbital branches of thetrigeminal nerve following inadvertent extrusion

of sodium hypochlorite beyond the root canalshave been reported.

Normal sensation may take many months tocompletely resolve.

Serper A, J Endod 2004;30:

180-181.


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Upper airway obstruction Leakage of the sodium hypochlorite solution into

the oral cavity and ingestion or inhalation by the

patient could result in throat irritation and insevere cases, the upper airway could becompromised.


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Fibre optic nasal tracheal intubation followed by

surgical decompression has been required to manageairway compromising swelling arising within threehours of accidental exposure to sodium hypochloriteduring root canal treatment.


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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 andoperator

The use of a sealed rubber dam for isolation of thetooth under treatment


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Irrigation needle a minimum of

2 mm short of the working length.

The use of side exit Luer-Lok needles for root canalirrigation

Avoidance of wedging the needle into the root canal.

Avoidance of excessive pressure during irrigation.


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References

Cohen’s PATHWAYS OF THE PULP- 10TH 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 inendodontics — potential complications and their

Management H. R. Spencer, V. Ike& P. A.Brennan:British Dental Journal 202, 555 - 559 (2007)


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Tissue-dissolving capacity and antibacterial effect of

buffered and unbuffered hypochlorite SolutionsMatthias 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 Journalof Dentistry, Volume 2011 (2011), Article ID 851359, 9pages

G. Sundqvist, “Ecology of the root canal flora,” Journalof Endodontics, vol. 18, no. 9, pp. 427– 430, 1992


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Sodium Hypochlorite in Endodontics