Sodium hypochlorite

sodium hypochlorite, the most commonly used intracanal medicament

1. By
Dr.Anoop.V.Nair
PG, Deptof Cons Dentistry & Endodontics
SODIUM
HYPOCHLORITE

2. 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

3. INTRODUCTION

4. •Maincauseofendodonticfailure-Microorganisms,eitherremaininginthe
rootcanalspaceaftertreatmentorre-colonizingthefilledcanalsystem.
•Primaryendodontictreatmentgoal-optimizerootcanaldisinfectionandto
preventre-infection.
•Pulpitisisthehostreactiontoopportunisticpathogensfromtheoral
environmententeringtheendodontium.
•Vitalpulptissuecandefendagainstmicroorganismsandisthuslargely
noninfecteduntilitgraduallybecomesnecrotic.Incontrast,thepulpspaceof
nonvitalteethwithradiographicsignsofperiapicalrarefactionalways
harborscultivablemicroorganisms.
•Consequently,thetreatmentofvitalcasesshouldfocusonasepsis,i.e.the
preventionofinfectionenteringaprimarilysterileenvironment,whichisthe
apicalportionoftherootcanal.Antisepsis,whichistheattempttoremoveall
microorganisms,isthekeyissueinnonvitalcases.

5. •Success,longevity,andreliabilityofmodernendodontictreatments-
effectivenessofendodonticfiles,rotaryinstrumentation,irrigatingsolutions,
andchelatingagentstoclean,shape,anddisinfectrootcanals.
•Theroleofmicroorganismsinthedevelopmentandperpetuationofpulp
andperiapicaldiseaseshasclearlybeendemonstratedinanimalmodels
andhumanstudies.
•Eliminationofmicroorganismsfrominfectedrootcanalsisacomplicated
task.
•Thechancesofafavourableoutcomewithrootcanaltreatmentare
significantlyhigherifinfectioniseradicatedeffectivelybeforetherootcanal
systemisobturated.
•However,ifmicroorganismspersistatthetimeofobturation,orifthey
penetrateintothecanalafterobturation,thereisahighriskoftreatment
failure

6. •Self-aggregatesofmonobacterialmorphotypesandcoaggregatesof
differentbacterialmorphotypesarealsofoundadheringtoteeth.
•Theinterbacterialspacesareoccupiedbyanamorphousmaterial,
spirochetes,andhyphal-likestructuresthataresuggestiveoffungi.
•Costertonetal.usedtheterm“biofilm”todescribethisclusteringof
bacteria.Bacteriawithinabiofilmhaveincreasedresistancetoavarietyof
externalhostileinfluences,suchasthehostdefenseresponses,antibiotics,
antiseptics,andshearforces,comparedwithisolatedbacterialcells.
* 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.

7. •Numerousmeasureshavebeendescribedtoreducethenumberof
microorganismsintherootcanalsystem,includingtheuseofvarious
instrumentationtechniques,irrigationregimens,andintracanal
medicaments.
•Theuseofchemicalagentsduringinstrumentationtocompletelycleanall
aspectsoftherootcanalsystemiscentraltosuccessfulendodontic
treatment.Irrigationiscomplementarytoinstrumentationinfacilitating
theremovalofpulptissueand/ormicroorganisms.
•Irrigationdynamicsplaysanimportantrole;theeffectivenessofirrigation
dependsontheworkingmechanism(s)oftheirrigantandtheabilitytobring
theirrigantincontactwiththemicroorganismsandtissuedebrisintheroot
canal.

8. RootCanalBacterium
•Primaryrootcanalinfectionsarepolymicrobial,typicallydominatedbyobligatory
anaerobicbacteria.
•Themostfrequentlyisolatedmicroorganismsbeforerootcanaltreatmentinclude
Gram-negativeanaerobicrods,Gram-positiveanaerobiccocci,Gram-positive
anaerobicandfacultativerods,Lactobacillusspecies,andGram-positivefacultative
Streptococcusspecies.
•Theobligateanaerobesarerathereasilyeradicatedduringrootcanaltreatment.
•FacultativebacteriasuchasnonmutansStreptococci,Enterococci,andLactobacilli,
onceestablished,aremorelikelytosurvivechemomechanicalinstrumentationand
rootcanalmedication.
•Enterococcusfaecalishasgainedattentionintheendodonticliterature,asitcan
frequentlybeisolatedfromrootcanalsincasesoffailedrootcanaltreatments.
•Yeastsmayalsobefoundinrootcanalsassociatedwiththerapy-resistantapical
periodontitis.

9. RootCanalIrrigants
•Itisgenerallybelievedthatmechanicalenlargementofcanalsmustbe
accompaniedbycopiousirrigationinordertofacilitatemaximum
removalofmicroorganismssothatthepreparedcanalbecomesas
bacteria-freeaspossible.
•Ideallyanirrigantshouldprovideamechanicalflushingaction,be
microbiocidalanddissolveremnantsoforganictissueswithout
damagingtheperiradiculartissuesifextrudedintotheperiodontium.
•Inaddition,therootcanalirrigantsshouldbebiocompatiblewithoral
tissues.

10. IdealRequirementofRootCanalIrrigants
Itappearsevidentthatrootcanalirrigantsideallyshould
(i)haveabroadantimicrobialspectrumandhighefficacyagainstanaerobicand
facultativemicroorganismsorganizedinbiofilms
(ii)dissolvenecroticpulptissueremnants,
(iii)inactivateendotoxin,
(iv)preventtheformationofasmearlayerduringinstrumentationordissolvethelatter
onceithasformed,
(v)besystemicallynontoxic,
(vi)benoncaustictoperiodontaltissues,
(vii)belittlepotentialtocauseananaphylacticreaction.

11. •Haveabroadantimicrobialspectrumandhighefficacyagainst
anaerobicandfacultativemicroorganismsorganizedinbiofilms
●Dissolvenecroticpulptissueremnants
●Inactivateendotoxin
●Preventtheformationofasmearlayerduringinstrumentationor
dissolvethelatteronceithasformed.
Furthermore,asendodonticirrigantscomeincontactwithvitaltissues,
theyshouldbesystemicallynontoxic,noncaustictoperiodontaltissues
andhavelittlepotentialtocauseananaphylacticreaction.
Root Canal Irrigants, J Endod2006;32:389–398
Matthias Zehnder

12. •Alargenumberofsubstanceshavebeenusedasrootcanalirrigants,
includingacids(citricandphosphoric),chelatingagent(ethylene
diaminetetraaceticacidEDTA),proteolyticenzymes,alkalinesolutions
(sodiumhypochlorite,sodiumhydroxide,urea,andpotassiumhydroxide),
oxidativeagents(hydrogenperoxideandGly-Oxide),localanesthetic
solutions,andnormalsaline.
•Themostwidelyusedendodonticirrigantis0.5%to6.0%sodium
hypochlorite(NaOCl),becauseofitsbactericidalactivityandabilityto
dissolvevitalandnecroticorganictissue.
•However,NaOClsolutionsexertnoeffectsoninorganiccomponentsof
smearlayer.
•Chelantandacidsolutionshavebeenrecommendedforremovingthesmear
layerfrominstrumentedrootcanals,includingethylenediaminetetraacetic
acid(EDTA),citricacid,andphosphoricacid

13. •Sodiumhypochloriteisthemostcommonlyused
endodonticirrigant,despitelimitations.Noneofthe
presentlyavailablerootcanalirrigantssatisfythe
requirementsofidealrootcanalirrigant.Newerrootcanal
irrigantsarestudiedforpotentialreplacementofsodium
hypochlorite.
Newer Root Canal Irrigantsin Horizon: A Review
SushmaJajuand PrashantP. Jaju
International Journal of Dentistry
Volume 2011 (2011), Article ID 851359, 9 pages
doi:10.1155/2011/851359

14. •Mostcommonlyusedirrigatingsolution
•Excellentantibacterialagent
•Capableofdissolvingnecrotictissue,vitalpulptissue,organiccomponentsof
dentinandbiofilms
•Bleach-disinfectantorbleachingagent
•Irrigantofchoiceinendodontics,efficacyagainstpathogenicorganismsand
pulpdigestion
•lowviscosityallowingeasyintroductionintothecanalarchitecture*
•acceptableshelflife*
•easilyavailableandinexpensive*
* 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)

15. Natural Occurrence
•Chlorineisoneofthemostwidelydistributedelementsonearth.Itis
notfoundinafreestateinnature,butexistsincombinationwith
sodium,potassium,calcium,andmagnesium.
•Inthehumanbody,chlorinecompoundsarepartofthenonspecific
immunedefense.
•Theyaregeneratedbyneutrophilsviathemyeloperoxidase-mediated
chlorinationofanitrogenouscompoundorsetofcompounds.

16. HISTORY
•Potassiumhypochloritewasthefirstchemicallyproducedaqueous
chlorinesolution,inventedinFrancebyBerthollet(1748-1822).
•Startinginthelate18thcentury,thissolutionwasindustrially
producedbyPercyinJavelnearParis,hencethename“Eaude
Javel”.
•First,hypochloritesolutionswereusedasbleachingagents.
•Subsequently,sodiumhypochloritewasrecommendedbyLabarraque
(1777-1850)topreventchildbedfeverandotherinfectiousdiseases.
•BasedonthecontrolledlaboratorystudiesbyKochandPasteur,
hypochloritethengainedwideacceptanceasadisinfectantbytheend
ofthe19thcentury.

17. •InWorldWarI,thechemistHenryDrysdaleDakinandthesurgeon
AlexisCarrelextendedtheuseofabuffered0.5%sodiumhypochlorite
solutiontotheirrigationofinfectedwounds,basedonDakin’s
meticulousstudiesontheefficacyofdifferentsolutionsoninfected
necrotictissue.
•Besidetheirwide-spectrum,nonspecifickillingefficacyonallmicrobes,
hypochloritepreparationsaresporicidal,virucidal,andshowfargreater
tissuedissolvingeffectsonnecroticthanonvitaltissues.
•Thesefeaturespromptedtheuseofaqueoussodiumhypochloritein
endodonticsasthemainirrigantasearlyas1920.
•Otherchlorine-releasingcompoundshavebeenadvocatedin
endodontics,suchaschloramine-Tandsodiumdichloroisocyanurate.
•These,however,havenevergainedwideacceptanceinendodontics,
andappeartobelesseffectivethanhypochloriteatcomparable
concentration.

18. CHEMISTRY
•Reactivechlorineinaqueoussolutionatbodytemperaturecan,inessence,
taketwoforms:hypochlorite(OCl
-
)orhypochlorousacid(HOCl).
•Theconcentrationofthesecanbeexpressedasavailablechlorineby
determiningtheelectrochemicalequivalentamountofelementalchlorine.
Accordingtothefollowingequations:
•Therefore,1molofhypochloritecontains1molofavailablechlorine.
•ThestateofavailablechlorineisdependingonthepHofthesolution.
•AboveapHof7.6,thepredominantformishypochlorite,belowthisvalueit
ishypochlorousacid.
•Bothformsareextremelyreactiveoxidizingagents.
•PurehypochloritesolutionsastheyareusedinendodonticshaveapHof12,
andthustheentireavailablechlorineisintheformofOCl
-
.

19. •However,atidenticallevelsofavailablechlorine,hypochlorousacidis
morebactericidalthanhypochlorite.
•Onewaytoincreasetheefficacyofhypochloritesolutionscouldthus
betolowertheirpH.
•Onealternativeapproachtoimprovetheeffectivenessofhypochlorite
irrigantsintherootcanalsystemcouldbetoincreasethe
temperatureoflow-concentrationNaOClsolutions.Thisimproves
theirimmediatetissue-dissolutioncapacity.
•Furthermore,heatedhypochloritesolutionsremoveorganicdebris
fromdentinshavingsmoreefficientlythanunheatedcounterparts.

20. •Ultrasonicactivationofsodiumhypochloritehasalsobeenadvocated,
asthiswould“acceleratechemicalreactions,createcavitational
effects,andachieveasuperiorcleansingaction”.
•However,resultsobtainedwithultrasonicallyactivatedhypochlorite
versusirrigationalonearecontradictory,bothintermsofrootcanal
cleanlinessandremainingmicrobiotaintheinfectedrootcanalsystem
afterthecleaningandshapingprocedure.
•Theobservedeffectsofultrasonicactivation,ifany,wererelatively
minor.
•Ultrasonicenergymaysimplyproduceheat,thusrenderingthe
hypochloriteslightlymoreactive.

21. MODE OF ACTION
•Inuseforalmostacentury
•Possessesbroadspectrumantimicrobialactivityagainstendodontic
microorganismsandbiofilms,includingmicrobiotadifficulttoeradicatefrom
rootcanalssuchasEnterococcus,ActinomycesandCandida
•Dissolvesorganicmaterialsuchaspulptissueandcollagen
•Bacteriainsidemainrootcanal,lateralcanalsanddentinaltubules-ifin
directcontactwithirrigant-aredestroyed.
•Sodiumhypochloritereactswithfattyacidsandaminoacidsindentalpulp
resultinginliquefactionoforganictissue.
•Thereisnouniversallyacceptedconcentrationofsodiumhypochloritefor
useasanendodonticirrigant.
•Theantibacterialandtissuedissolutionactionofhypochloriteincreaseswith
itsconcentration,butthisisaccompaniedbyanincreaseintoxicity.

22. •Dakin’soriginal0.5%sodiumhypochloritesolutionwasdesignedto
treatopen(burnt)wounds,itwassurmisedthatintheconfinedareaof
arootcanalsystem,higherconcentrationsshouldbeused,asthey
wouldbemoreefficientthanDakin’ssolution
•Theantibacterialeffectivenessandtissuedissolutioncapacityof
aqueoushypochloriteisafunctionofitsconcentration.
•Severeirritationshavebeenreportedwhensuchconcentrated
solutionswereinadvertentlyforcedintotheperiapicaltissuesduring
irrigationorleakedthroughtherubberdam
•Furthermore,a5.25%solutionsignificantlydecreasestheelastic
modulusandflexuralstrengthofhumandentincomparedto
physiologicsaline,whilea0.5%solutiondoesnot.

23. •Thereductionofintracanalmicrobiota,ontheotherhand,isnotanygreater
when5%sodiumhypochloriteisusedasanirrigantascomparedto0.5%.
•Frominvitroobservations,itwouldappearthata1%NaOClsolutionshould
sufficetodissolvetheentirepulptissueinthecourseofanendodontic
treatmentsession.
•Itmustberealizedthatduringirrigation,freshhypochloriteconsistently
reachesthecanalsystem,andconcentrationofthesolutionmaythusnot
playadecisiverole.
•Uncleanareasmaybearesultoftheinabilityofsolutionstophysicallyreach
theseareasratherthantheirconcentration.
•Hence,basedonthecurrentlyavailableevidence,thereisnorationalefor
usinghypochloritesolutionsatconcentrationsover1%wt/vol.

24. Infected dentin blocks-0.25% sufficient to kill E.faecalisin 15 mins,
concof 1% requires 1 hrto kill Candida albicans
*Ruffetal.,ininfectedextractedteeth,foundthat1minapplicationof6%
NaOCland2%chlorhexidineequallyeffectiveineliminating
microorganismsandstatisticallysignificantlysuperiortoMTADand17%
EDTAineliminatingCandidaalbicansinfections

25. •Commercially available household bleach-Clorox6.15% NaOCl,
alkaline pH-11.4, hypertonic
•Some authors recommend, dilution of cloroxwith 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 NaOCland recommend dilution with water to obtain less
conc. irrigation solutions.
* SplangbergLSW, HaapasaloM: Rationale and efficacy of root canal medicaments
and root filling material with emphasis on treatment outcome.EndodTopics 2:35,2002

26. SUGGESTED IRRIGATION REGIMEN
•Thechemicalsusedtocleaninfectedcanalsshouldbeadministeredinsuch
mannerthattheycanunleashtheirfullpotentialontheirtargetsintheroot
canalratherthanactoneachother.
•Hence,ahypochloritesolutionshouldbeemployedthroughoutinstrumentation,
withoutalteringitwithEDTAorcitricacid.
•‘Canalsshouldalwaysbefilledwithsodiumhypochlorite’.
•Thiswillincreasetheworkingtimeoftheirrigant.
•Inaddition,cuttingefficacyofhandinstrumentsisimprovedandtorsionalloadon
rotarynickel-titaniuminstrumentsisreducedinfluid-filledenvironmentscomparedto
dryconditions.
•Ontheotherhand,corrosionofinstrumentsinprolongedcontactwithhypochlorite
isanissue.
•Submersinginstrumentsforhoursinahypochloritesolutionwillinducecorrosion.
•However,noadverseeffectsshouldbeexpectedduringtheshortcontactperiods
whenaninstrumentismanipulatedinarootcanalfilledwithhypochlorite.

27. •Afterthesmearremovingprocedureafinalrinsewithanantisepticsolution
appearsbeneficial.Thechoiceofthefinalirrigantdependsonthenext
treatmentstep,i.e.whetheranintervisitdressingisplannedornot.
•Ifcalciumhydroxideisusedfortheinterim,thefinalrinseshouldbesodium
hypochlorite,asthesetwochemicalsareperfectlycomplementary.It
appearsevenadvantageoustomixcalciumhydroxidepowderwiththe
sodiumhypochloriteirrigantratherthanwithsalinetoobtainamore
effectivedressing.
•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.
•‘Substantivityis not observed with sodium hypochlorite.’

28. 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
•Actinomycesorganisms-
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 kill all cells in culture
1 min of 6% solution: no growth

29. •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
NaOClto 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.

30. Increasing efficacy of hypochlorite preparations
•IncreasingtemperatureoflowconcentrationNaOClsolutions-which
improvetheirimmediatetissue-dissolutioncapacity.
•Heatedhypochloritesolutionsremoveorganicdebrisfromdentinshavings
moreefficiently
•AntimicrobialpropertiesofheatedNaOCl-bactericidalratesmorethan
doubledforeach5
O
riseintemperatureintherangeof5-60
0
.

32. 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%.
(SirtesG, WaltimoT, SchaetzleM, Zehnder
M: The effects of temperature on sodium
hypochlorite short-term stability, pulp
dissolution capacity and antimicrobial
efficacy. J Endod31:669-671, 2005)

33. •Studieshaveshownthat1minat47
o
cisthecutoffexposureatwhich
osteoblastscanstillsurvive,however,highertemperaturesmayinfactbe
sufficienttokillosteoblastsandotherhostcells.
•WarmingofNaOClto50
o
cor60
o
cincreasescollagendissolutionand
disinfectingpotential,butitmayalsohaveseverelydetrimentaleffectson
NiTiinstruments,causingcorrosionofthemetalsurfaceafterimmersionfor
1hour
Rotary instrument immersed for 2 hours in NaOClheated to 60
o
c, showing severe
corrosion

34. •AstudyusingsteadystateplanktonicE.fecaliscells,showeda
temperatureriseof25
o
cincreasedNaOClefficacybyafactorof
100.
•Capacitytodissolvehumandentalpulpusing1%NaOClat45
o
c
wasfoundtobeequaltothatofa5.25%solutionat20
o
c.
•SystemictoxicityofpreheatedlowconcofNaOClirrigantsshould
belessthanthatofamoreconcentratedunheatedsolution.

35. Time factor
•NaOClrequireanadequateworkingtimetoreachtheirpotential.
•Chlorine,whichisresponsiblefordissolvingandantibacterialcapacityof
NaOCl-unstableandconsumedrapidlyduringthefirstphaseoftissue
dissolution,probablywithin2mins.
•Optimaltimeahypochloriteirrigantneedstoremaininthecanalsystemis
anissueyettoberesolved.
* Cohen-Pathways of the pulp, 10
th
edition

36. INTERACTIONS
•Antimicrobialactivity,dissolvingoftheremainingpulptissues,
lubricationduringmechanicalinstrumentation,availabilityandlow
costarethefundamentalrequirementsforrootcanalirrigants
(Zehnder2006,Haapasaloetal.2010).
•Sodiumhypochlorite-mostcommonirrigant,othersolutionsmostly
usedalongwithsodiumhypochlorite,asafinalrinsetoenhancethe
antimicrobialactivityandsubstantivityagainstsomeresistant
bacteria,todecreasethecausticeffectortoaidinremovingthe
smearlayer.
(Zehnder2006,Mohammadi&Abbott2009,Haapasaloetal.2010).

37. NaOClhasbeenreportedtocausedentinediscolouration,although
itisableachingagent.
Thisdiscolourationisaresultofitscontactwitherythrocytesandits
hightendencytocrystallizeontherootdentine,whichmaymean
thatitisdifficulttocompletelyremovefromthecanal(Gutie´rrez&
Guzma´n1968).Inaddition,thecombinationofNaOClwithother
adjunctirrigatingsolutionshasbeenfoundtocausemarkedtooth
discolourations
Vivacqua-Gomesetal.(2002)observedadarkbrownprecipitate
whenNaOClwascombinedwithchlorhexidine(CHX)gel.Other
authorshavereportedthesametypeofdiscolourationwhen
NaOClhasbeenusedwithCHXsolutions(Basranietal.2007,
Marchesanetal.2007,Buietal.2008,Akisueetal.2010,
Krishnamurthy&Sudhakaran2010,Nassaretal.2011,Souzaet
al.2011)

38. Discolourationwhen irrigantsare 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).

39. Thisdarkbrownprecipitatecanstainthedentine,adheretothefloorofthepulp
chamber,accesscavityandrootcanalwallsandactasaresidualfilmthatmay
compromisethediffusionofintra-canalmedicamentsintothedentine,disruptthe
adhesionoftherootcanalfillingandfavourcoronalrestorationbreakdown
(Vivacqua-Gomesetal.2002,Akisueetal.2010)
DiscolourationpotentialofNaOCl/CHXcombinationontheaccesscavitywalls.
(a)NaOCl
(b)DarkbrownprecipitateafterNaOCl/CHXcombination
(c)Theprecipitatebecomesadherenttotheaccesscavitywalls(whitearrow)and
crownfissures(redarrow)evenafterflushingwithdistilledwater.

40. Basranietal.(2007)examinedthisprecipitateusingX-rayphotoelectron
spectroscopy(XPS)andtime-of-flightsecondaryionmassspectrometry
(TOF-SIMS),andtheyfoundthatitcontainsasignificantamountof
parachloroaniline(PCA).
Thissubstanceiscarcinogenicanditcanfurtherdegradeto1-chloro-4-
nitrobenzene,whichalsoiscarcinogenic.
However,byusingnuclearmagneticresonance(NMR),Thomas&Sem
(2010)reportedthatmixingNaOClandCHXdidnotproducePCAatany
measurablequantity,butoneoftheCHXbreakdownproductsmaybefurther
metabolizedtoPCA(Nowicki&Sem2011).

41. Asaresultofthesepossiblehazards,Kimetal.(2012)examinedthe
chemicalinteractionbetweenAlexidine(ALX),asasubstituteforCHX,and
NaOClusingelectrosprayionizationmassspectrometry(ESIMS)and
scanningelectronmicroscopy(SEM).
TheresultsrevealedthattheassociationofALX/NaOCldidnotproducePCA
oranyprecipitate,andthemixingsolutionsofALXandNaOClresultedina
slightdiscolourationrangingfromlightyellowtotransparentastheALX
concentrationdecreased.
Inaddition,thiscombinationdidnotstaindentineandwaseasytoremove
fromtherootcanalbyirrigation.

42. NaOClalso reacts with MTAD(a mixture of a tetracycline isomer, an acid
[citric acid], and a detergent) (DentsplyTulsa Dental, Tulsa, OK, USA), in the
presence of light, causing brown discolouration(Torabinejadet al. 2003).
This reaction may be caused by the dentinal absorption and release of the
doxycycline, present in MTAD, which will be exposed to NaOClif it is used as
a final rinse after MTAD (Torabinejadet al. 2003).

43. Tayetal.(2006a)formationofyellowprecipitatealongtherootcanalwallswhen
NaOClwasusedasanirrigantandthenfollowedbytheapplicationofBioPure
MTADasafinalrinse.
Theyalsoobservedred-purplestainingoflight-exposed,root-treateddentinewhen
therootcanalswererinsedwith1.3%NaOClasaninitialrinsefollowedbyMTADas
thefinalrinse.

44. Thisphoto-oxidativedegradationprocesswasprobablytriggeredbytheuse
ofNaOClasanoxidizingagentwhichalsoresultedinpartiallossofits
antimicrobialsubstantivity(Tayetal.2006a,b).
ThechemicalreactionbetweenNaOClandcitricacid,whichleadstothe
formationofawhiteprecipitate,indicatesacomplexinteractionbetween
NaOClandMTADthatrequiresfurtherinvestigationstovalidatethesafety
andusefulnessofthiscombinationofirrigants.
Gonza´lez-Lo´pezet al. (2006) and Rasimicket al. (2008) have reported
interactions between CHX and EDTA irrigantswith the formation of white to
pink precipitate.

45. Practitioners should choose irrigating solutions carefully to suit the clinical
condition that is being treated.
IfCHXischosen,thentheinsolubledarkbrownprecipitate,createdwhenNaOCland
CHXaremixed,canbeavoidedbyincorporatingathoroughintermediateflush
betweeneachirrigant–thiscanbecarriedoutwithsolutionssuchassalineorsterile
distilledwater,followedbydryingofthecanalbeforethenextsolutionisused
(Krishnamurthy&Sudhakaran2010).
Absolutealcoholhasalsobeensuggestedasanintermediateflushbutits
biocompatibilitywiththeperiapicaltissuesandinteractionswithotherirrigantsremain
aconcern(Krishnamurthy&Sudhakaran2010,Valeraetal.2010)

46. Nassaret al. (2011) recommended the use of sodium ascorbateto prevent
the formation of this precipitate.
Ascorbic acid solution, as a reducing agent, has been advocated as an
intermediate flush between NaOCland MTAD, to prevent the oxidation effect
of NaOCland to avoid the photodegradationof the doxycycline that is present
in MTAD (Tayet al. 2006a). In addition, the possible interaction between
NaOCland 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 (Ballalet 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(Ballalet al. 2011).

47. Tooth discolourationassociated with root canal irrigants
Irrigating solutions Type of discolouration Author/s –year
NaOCl(undiluted and 10%) Some discolouringeffect Gutie´rrezand 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 (NaOClfinal rinse) Torabinejadet al. (2003)
17% EDTA + 1% CHX sol. Pink precipitate (CHX final rinse) Gonza´lez-Lo´pezet al. (2006)
2% CHX sol. + 17% EDTA White precipitate Rasimicket al. (2008)
1.54–6.15% NaOCl+ MTAD Yellow precipitate (MTAD final rinse) Tayet al. (2006a) (Clinical application)
1.3% NaOCl+ MTAD Red-purple (MTAD final rinse) Tayet 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), Nassaret al. (2011)
2% CHX sol. + 15% Citric acid A white solution but returns Akisueet al. (2010)
colourlessand easily removed
during irrigation with CHX
2% CHX gel + 5.25% NaOCl Discolouredenamel and dentine Souza et al. (2011)
2% CHX sol. + 5.25% NaOCl Discoloureddentine only Souzaet al. (2011)
2% CHX gel + 5.25% NaOCl+ 17% EDTA Discolouredenamel and dentine Souza et al. (2011)
2% CHX sol. + 5.25% NaOCl+ 17% EDTA Discoloureddentine Souzaet al. (2011)

48. ALLERGICREACTIONS
•Unlikelytooccur,sincebothsodiumandchlorineareessentialelementsin
thephysiologyofhumanbody
•Hypersensitivityandcontactdermatitis-rarecases
•Incasesofhypersensitivity-chlorhexidineshouldnotbeusedeither-dueto
chlorinecontent
•Alternativeirrigant-iodinepotassiumiodide,highantimicrobialefficacy
•Alcohol,tapwater-lesseffectiveagainstmicroorganisms,donotdissolve
vitalornecroticpulptissue.
•Ca(OH)
2-temporarymedicament,dissolvesbothvitalandnecrotictissue.

49. •Theallergicpotentialofsodiumhypochloritewasfirstreportedin1940by
SulzbergerandsubsequentlybyCohenandBurns.
•Caliskanetal.presentedacasewherea32-year-oldfemaledevelopedrapid
onsetpain,swelling,difficultyinbreathingandsubsequentlyhypotension
followingapplicationof0.5mlof1%sodiumhypochlorite.Thepatient
requiredurgenthospitalizationintheintensivecareunitandmanagement
withintravenoussteroidsandantihistamines.
•Subsequentallergyskinscratchtestperformedtwoweeksafterthepatient
wasdischargedconfirmedahighlypositiveresulttosodiumhypochlorite.The
usefulnessofthistestinsuspectedcasesofsodiumhypochloriteallergy
duringendodontictreatmenthasbeenconfirmedbyKaufmanandKeila.
•Symptomsofallergyandpossibleanaphylaxis-urticaria,oedema,shortness
ofbreath,wheezing(bronchospasm)andhypotension.
•Urgentreferraltoahospitalfollowingfirstaidmanagementisrecommended.
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)

50. •Toavoidextrusionandseriousdamagetoperiapicaltissues,
irrigationneedlesshouldneverbewedgedintocanalsduring
irrigation.
•HigherconcentrationNaOCl-moreaggressivetowardlivingtissue
andcancausesevereinjurieswhenforcedintoperiapicalarea.
27 gauge needle 30 gauge side
venting needle

51. Toxic effect of sodium hypochlorite on periradiculartissues.
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.

52. 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 irrigantextrusion

53. Complications of accidental spillage
1)Damagetoclothing
Accidentalspillageofsodiumhypochloriteisprobablythemostcommonaccident
tooccurduringrootcanalirrigation.
Evenspillageofminutequantitiesofthisagentonclothingwillleadtorapid,
irreparablebleaching.
Thepatientshouldwearaprotectiveplasticbib,andthepractitionershould
exercisecarewhentransferringsyringesfilledwithhypochloritetotheoralcavity.
2)Eyedamage
Seeminglymildburnswithanalkalisuchassodiumhypochloritecanresultin
significantinjuryasthealkalireactswiththelipidinthecornealepithelialcells,
formingasoapbubblethatpenetratesthecornealstroma.Thealkalimovesrapidly
totheanteriorchamber,makingrepairdifficult.Furtherdegenerationofthetissues
withintheanteriorchamberresultsinperforation,withendophthalmitisand
subsequentlossoftheeye.

54. •Ingramrecordedacaseofaccidentalspillageof5.25%sodiumhypochlorite
intoapatient'seyeduringendodontictherapy.
•Theimmediatesymptomsincludedinstantseverepainandintenseburning,
profusewatering(epiphora)anderythema.
•Lossofepithelialcellsintheoutercorneallayermayoccur.
•Theremaybeblurringofvisionandpatchycolourationofthecornea.
•Immediateocularirrigationwithalargeamountofwaterorsterilesalineis
requiredfollowedbyanurgentreferraltoanophthalmologist.
•Thereferralshouldideallybemadeimmediatelybytelephonetothenearest
eyedepartment.
•Theuseofadequateeyeprotectionduringendodontictreatmentshould
eliminatetheriskofoccurrenceofthisaccident,butsterilesalineshould
alwaysbeavailabletoirrigateeyesinjuredwithhypochlorite.
•Ithasbeenadvisedthateyesexposedtoundilutedbleachshouldbeirrigated
for15minuteswithalitreofnormalsaline.

55. 3)Damagetoskin
•Skininjurywithanalkalinesubstancerequiresimmediateirrigationwithwater
asalkaliscombinewithproteinsorfatsintissuetoformsolubleprotein
complexesorsoaps.Thesecomplexespermitthepassageofhydroxylions
deepintothetissue,therebylimitingtheircontactwiththewaterdilutantonthe
skinsurface.
•Wateristheagentofchoiceforirrigatingskinanditshouldbedeliveredatlow
pressureashighpressuremayspreadthehypochloriteintothepatient'sor
rescuer'seyes.
4)Damagetooralmucosa
•Surfaceinjuryiscausedbythereactionofalkaliwithproteinandfatsas
describedforeyeinjuriesabove.Swallowingofsodiumhypochloriterequires
thepatienttobemonitoredfollowingimmediatetreatment.Itisworthnoting
thatskindamagecanresultfromsecondarycontamination.
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)

56. Complications arising from hypochlorite extrusion beyond the root
apex
1)Chemicalburnsandtissuenecrosis
•Whensodiumhypochloriteisextrudedbeyondtherootcanalintotheperi-
radiculartissues,theeffectisoneofachemicalburnleadingtoalocalisedor
extensivetissuenecrosis.
•Giventhewidespreaduseofhypochlorite,thiscomplicationisfortunatelyvery
rareindeed.
•Asevereacuteinflammatoryreactionofthetissuesdevelops.
•Thisleadstorapidtissueswellingbothintraorallywithinthesurrounding
mucosaandextraorallywithintheskinandsubcutaneoustissues.
•Theswellingmaybeoedematous,haemorrhagicorboth,andmayextend
beyondtheregionthatmightbeexpectedwithanacuteinfectionoftheaffected
tooth
.

57. Bruising and oedemaof patients who presented with hypochlorite extrusion into the
soft tissues

58. •Suddenonsetofpainisahallmarkoftissuedamage,andmayoccur
immediatelyorbedelayedforseveralminutesorhours.
•Involvementofthemaxillarysinuswillleadtoacutesinusitis.
•Associatedbleedingintotheinterstitialtissuesresultsinbruisingand
ecchymosisofthesurroundingmucosaandpossiblythefacialskinand
mayincludetheformationofahematoma.
•Anecroticulcerationofthemucosaadjacenttothetoothmayoccurasa
directresultofthechemicalburn.
•Thisreactionofthetissuesmayoccurwithinminutesormaybedelayed
andappearsomehoursordayslater.

59. •Ifthesesymptomsdevelop,urgenttelephonereferralshouldbemadeto
thenearestmaxillofacialunit.
•Patientswillbeassessedbytheoncallmaxillofacialteam.
•Treatmentisdeterminedbytheextentandrapidityofthesofttissue
swellingbutmaynecessitateurgenthospitalizationandadministrationof
intravenoussteroidsandantibiotics.
•Althoughtheevidencefortheuseofantibioticsinthesepatientsis
anecdotal,secondarybacterialinfectionisadistinctpossibilityinareas
ofnecrotictissueandthereforetheyareoftenprescribedaspartofthe
overallpatientmanagement.
•Surgicaldrainageordebridementmayalsoberequireddependingon
theextentandcharacterofthetissueswellingandnecrosis.

61. 2) Neurological complications
-Paraesthesiaand anaesthesiaaffecting the mental, inferior dentaland
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 Wittonet al. in 2005.
-In both cases, the buccalbranch 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.

62. 3)Upperairwayobstruction
Theuseofsodiumhypochloriteforrootcanalirrigationwithoutadequateisolationof
thetoothcanleadtoleakageofthesolutionintotheoralcavityandingestionor
inhalationbythepatient.
Thiscouldresultinthroatirritationandinseverecases,theupperairwaycouldbe
compromised.
Zieglerpresentedacaseofa15-month-oldgirlwhopresentedintheaccidentand
emergencyunitwithacutelaryngotrachealbronchitis,stridorandprofusedrooling
fromthemouthasaresultofingestionofahighconcentrationofhouseholdsodium
hypochlorite.
Asimilarclinicalpresentationmightoccurwiththeingestionofanycaustic
substance.
Opinionvariesastothebestconcentrationofhypochlorite,withsomepractitioners
usingundilutedhouseholdbleach.Fibreopticnasaltrachealintubationfollowedby
surgicaldecompressionhasbeenrequiredtomanageairwaycompromising
swellingarisingwithinthreehoursofaccidentalexposuretosodiumhypochlorite
duringrootcanaltreatment

63. •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

64. Placement of rubber stop on irrigation needle
•Needlemustbesideventing
•Hypodermic(endexiting)needlesinrootcanal
irrigationrisksaccidentalinoculationintothesoft
tissues.
•Luer-Lokstylesyringesandneedlesshouldbeused,
astaperseatneedlesmaydislodgeinuse,with
uncontrolledlossofthehypochloritesolutionunder
pressure.
•Needleshouldnotengagethesidesofthecanal,but
belooselypositionedwithinthecanal.
•Needleshouldnotreachtheapicalextentofthe
preparedcanal.
•Thistechniquemaybefacilitatedbymarkingthe
workinglengthontheneedlewitharubberstop.
irrigantdeliveredslowlywithminimalpressureto
reducethelikelihoodofforcingitthroughtheapex.
Achievedbyusingyourindexfingerratherthan
thumbtodepresstheplunger.
•Thiswillreducetherisktoperiapicaltissuesby
inadvertentextrusionofirrigant.

65. 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

66. •Thedissolvingeffectoftheendodonticmedicamentscalciumhydroxide
(Ca(OH)
2)andsodiumhypochlorite(NaOCI)onnecrotictissuewas
studied.
•Piecesofnecroticporcinemusculartissuewereplacedineithera0.5%
NaOCIsolution(Dakin'ssolution),Ca(OH)
2,mixedwithwater,ora
NaOCIsolutionfollowingpretreatmentinCa(OH)
2forvarioustime
intervals.
•Thetissuepiecesplacedin0.5%NaOCIwerenotcompletelydissolved
after12days.WhenNaOCIsolutionwaschangedevery30min,the
tissuewascompletelydissolvedafter3h.
•PiecesplacedinCa(OH)
2exhibitedamarkedswellingandajelly-like
consistency.
Effects of calcium hydroxide and sodium hypochlorite on the dissolution
of necrotic porcine muscle tissue
GunnaHasselgren, BeritOlsson, MiomirCvek
JOE, Volume 14, Issue 3, March 1988, Pages 125–127

67. •Theincreaseinweightwasmaintainedfor24h,afterwhicha
decreasewasnoted.
•After12days,thetissuewascompletelydissolved.
•PretreatmentwithCa(OH)
2for30mincausedthetissuetodissolvein
NaOCIwithin90min.Piecesthatwerepretreatedfor24hor7days
dissolvedwithin60min.
•Asacontrol,tissuepieceswerekeptinisotonicsalinesolutionand
thesewerenotdissolvedafter12days.
•Apparently,long-termtreatmentwithCa(OH)
2candissolvenecrotic
tissueandpretreatmentwithCa(OH)
2canenhancethetissue
dissolvingeffectofNaOCl.

68. Tissue-dissolving capacity and antibacterial effect of buffered and
unbufferedhypochlorite solutions
MatthiasZehnder, DanielKosicki, HansueliLuder, BeatriceSener, TuomasWaltimo
Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and Endodontology
Volume 94, Issue 6 , Pages 756-762, December 2002
•ThegoalofthisstudywastocomparethedissolvingpotentialofDakin's
solutionwiththatofequivalentbufferedandunbufferedsodiumhypochlorite
solutionsonfreshanddecayedtissues.Inaddition,theantimicrobialeffectof
Dakin'ssolutionandequivalentunbufferedhypochloritewastested.
•StudyDesign.Tissuespecimenswereobtainedfromfreshlydissectedpig
palates.Unbuffered2.5%and0.5%sodiumhypochloritesolutionsand0.5%
solutionsbufferedatapHof12andapHof9(Dakin'ssolution)weretestedon
freshanddecayedtissue.Tissuedecaywasassessedhistologically.
AntimicrobialtestingwasperformedwithEnterococcusfaecalisindentin
blocksandonfilterpapers.

69. •Results
•The 2.5% NaOClsolution 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 unbufferedhypochlorite 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 NaOClwith water.

70. CONCLUSION
•Newconceptsusuallyareoverratedininitialstudieswhencomparedto
thegoldstandard.
•Somerecentapproachestoimproverootcanaldebridementinclude
theuseoflaserlighttoinducelethalphotosensitizationoncanal
microbiota,irrigationusingelectrochemicallyactivatedwater,and
ozonegasinfiltrationintotheendodonticsystem.
•However,intermsofkillingefficacyonendodonticmicrobiotain
biofilms,thereisgoodevidencethatnoneoftheseapproachescan
matchasimplesodiumhypochloriteirrigation.

71. References-
1.Cohen’s PATHWAYS OF THE PULP-10
TH
EDITION
2. Problem solving in Endodontics-fourth edition, GUTMANN, DUMSHA, LOVDAHL
3. Root Canal Irrigants, J Endod2006;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 unbufferedhypochlorite
solutions
MatthiasZehnder, DanielKosicki, HansueliLuder, BeatriceSener, TuomasWaltimo
OOOOE, Volume 94, Issue 6 , Pages 756-762, December 2002
6. Newer Root Canal Irrigantsin Horizon: A Review, SushmaJajuand PrashantP. 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

72. 7. “The synergistic antimicrobial effect by mechanical agitation and two chlorhexidinepreparations 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. * YesilroyC, Whitaker E, Cleveland D, PhilpsE, Trope M: Antibacterial and toxic effects of
established and potential root canal irrigants. J Endod21:513, 1995