Download Dr. Kim`s RCT Clinical Guide - Las Vegas Root Canal Specialist

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ROOTCANALTREATMENT:ACLINICALGUIDEFORDENTALSTUDENTS,
GENERALDENTISTSWHOLIKEDOINGRCTSANDGENERALDENTISTSWHOHATEDOINGRCTS©2016
GregY.Kim,DDS
Diplomate,AmericanBoardofEndodontics
Thisdocumentisintendedasaneasy-to-readguidefordentalstudentsandgeneralpractitionersofdifferent
clinicalcapacitywhoseektoimprovetheirrootcanaltreatmentskillsandobtainamoreconsistentlypredictable
outcomeintheireverydaypractice.Doingarootcanaltreatment(RCT),forthemostpart,isnotacomplicated
taskandtheprocedureshouldbecomeeasierandmoresystematicasthecliniciangainsmoreexperience.There
are,however,differentcomponentsofdevelopmentinbecomingamoreskilledclinician,andbecoming
technicallygoodisonlyoneaspectofit.Inordertobetrulyproficientinthisfield,aclinicianmustalsoimprove
his/herdiagnosticskillsandunderstandingofitsbiologicalprinciples.Thisguideisdividedintodifferenttopicsand
subtopicswhicharedeemedimportantforunderstandingofthosefundamentalendodonticprinciples.
DIAGNOSIS
Gooddiagnosticskillsareundeniablyimportantforbettermanagementofendodonticcases.Dayinanddayout,
weseeawholeslewoferrorsassociatedpoordiagnosis,whetheritbeprescribingwrongmedicationsor
treatment-planningforawrongprocedure.Theimportanceofthisfirststepoftreatmentcan’tbestressed
enough.Startingoutwithagooddiagnosisattheonsetcanreallysparethedentistofunnecessaryheadaches
duringfollow-upphase.Forthepurposeofthisguide,differentpulpalandperiapicaldiagnosesarenotgoingtobe
discussedcomprehensively,butsomeofthemostcommonerrorsassociatedwitheitherdoinganerroneous
diagnosisorNOdiagnosisdeserveadiscussionhere.
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PrescribingAntibioticsforPulpitis
Pulpitisbydefinitionisaninflammationofthepulptissueandcouldbeexceedinglypainfulunderacute
inflammatoryconditions.Forpainrelief,eitherthisinflamedpulptissueneedstoberemovedorthe
toothneedstoberemoved.Whenthepulpisstillvitalandinflamed(note:blooduponaccessopening),
takingantibioticsactuallydoesnothingforpainreliefandonlyaddsthehassleofhavingtotake
medicationsformultipledaysforanalreadydistressedpatient.Forantibioticstobeeffectiveatreducing
symptoms,thepulphastobenecroticandinfectedforthemostpart(note:absenceofbloodupon
enteringpulpspace).Now,ithastobenotedthatpercussionsensitivitycouldpresentwithbothvitaland
nonvitalpulp.But,ingeneral,thecaseswhereantibioticscanworkforpainreliefdonotrespondto
thermalstimuli(endoice,hotcoffee,etc.)butinsteaddisplaymarkedpercussionsensitivitythatcanbe
localizedbythepatient.Tendernessofsofttissueinthevestibuleneartheapicesoftheassociatedtooth
maybepresentaswell.Ontheotherhand,ifapatient’schiefcomplaintishavingseverepainupon
drinkingsomethingcoldorhot,donotgivethatpatientantibioticsforthepurposeofaddressingthat
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chiefcomplaint.Atleastdoapulpotomyifyouhavetime,orfindanendodontistwhocanprovidean
emergencytreatmentforyou.Besuretodoathoroughdiagnosisasmanypatientswillpresentwitha
tooththatisnecroticandinfectedbutwillalsocomplainofthermalsensitivityfromadjacentteethas
well.Thekeyistoaddressthetooththatisthemaincauseofacutesymptoms.
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NotInstrumentingtheCanalsforaNecroticToothwithInfectedRootCanals
Thisisanothercommonerrorcommonlyencountered.Whenpulpalinflammationprogressesandthe
pulpbecomesnecrotic,fullinstrumentationofthecanalsisrequiredtoeliminatetheinfectionandreduce
symptoms.Anecrotictoothhasinfectioninthecanals,themostcommoncauseofwhichisbacterial
insultfromcaries.Thesepatientscanpresentwithswollengumsand/orface.Instrumentingtoatleast
size30/04withagoodamountofsodiumhypochloriteirrigationisrecommended.Otherwise,givethe
patientantibiotics(oryoucandoboth)andthepatientwilltypicallyseereliefofsymptomswithinaday
ortwo.
Diagnosisdictatestreatments:A8-year-oldboypresentedwithanexposureof#9fromtrauma.Patient’shistoryofchiefcomplaint
anddiagnostictestsindicatedthatthepulpwasstillinareversiblestateofinflammation.Thetoothstructureimmediatelyadjacent
tothesiteofexposurewascleanedoutwithasmallroundburanddisinfectedwithsodiumhypochlorite.Thisareawascappedwith
aBioceramicPuttymaterialandthepatientwasreferredbacktothegeneraldentistforacompositerestoration.A9-monthfollowupshowed(despiteforeshorteninginthefirsttwox-rays)thatthetoothmaintaineditsvitalityandcontinueditsnormal
development.IfRCThadbeendonewithoutproperlydiagnosingthestateofthepulpandtheperiapex,thetoothwouldhave
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stoppeditsnormaldevelopmentandwouldhaveresultedinaclinicallymorecomplicatedsituation.(1 x-ray:Preop,2 x-ray:
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ImmediatePostop,3 x-ray:9MonthFollow-Up)
ANTIBIOTICS
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Thego-tomedicationforanodontogenicinfectionisPenVK500mg(bactericidal,narrowerspectrumof
actionthanamoxicillin,taken4timesperday).Forpatientswithamoxicillin/penicillinallergy,
Clindamycinshouldfirstbeconsidered.
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Forpatientswithalarge,noticeableswelling:Refertoanoralsurgeonifnottotallycomfortabledealing
withthesituation.Ifyougive2differentantibioticstogether,themosteffectivecombinationwouldbe2
bactericidalantibiotics,suchasPenVKandmetronidazole.Acombinationofbactericidaland
bacteriostaticantibiotics(suchaspenicillinwithclindamycin)maycounteracttheeffectivenessofeach
otherandmaynotbeashelpful.
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THETREATMENT:STEPBYSTEP
Beforeinitiatinganytreatment,takealong,closelookatthex-rays.Mostoftheworstexperiencesassociated
withrootcanalprocedures,byyouandbythepatient,canbeavoidedbychoosingNOTtodothemost
complicatedcases.Olderpatientshaveahigherlikelihoodofpresentingwithcalcifiedcanalsandmaynotbeable
totoleratelongertreatmentsessionsatthesametime.Ifyouhavedifficultydiscerningthecanalsdueto
calcification,itmaybeadvisabletorefertoaspecialist.Lookingatbitewingx-raysaswellasperiapicalscanalso
giveyouadditionalinformationastowhatkindofdifficultyleveltoexpect.
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Access
Agoodaccesscanfacilitatetherestoftheprocedure.Apooraccess,bythesametoken,canmakethe
proceduremoredifficultthanneeded.Studythebitewingx-raybeforepickingupahigh-speedhandpiece
togaugehowmuchyouhavetogodowntobeinthepulpchamber.Itshouldalwaysberemembered
thatthepulpchamberdepthislargestontopofthebiggercanals,meaningthatitwouldbeeasierto
exposethispartofthechamberfirstandthenpeelawayfromhere.Forexample,foruppermolars,it’s
easiesttoexposethepalatalcanalfirstbecauseit’sthelargestcanalwiththemostamountofcoronal
chamberspaceontopofit.Asyoupeelawaytheroofofthepulpchamber,adarkpulpalfloorreveals
itselfandtheothercanalsarefoundattheouteredgesofthisdarkerfloor.Italsohelpstoremember
thatthepulpchamberiscenteredandconcentricwiththetoothoutlineattheleveloftheCEJ.Makea
habitoflookingattheCEJoutlineandenvisioningthepulpchamberatthecenterofthiscrosssection.
Doingthisoccasionallywhileaccess-preppingcanhelpyougetreorientedifyouaredrillinginawrong
direction.Caution:ThisinformationregardingtheCEJmaybedistortedincrownedteeth.
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MeasuringWorkingLength
Theveryfirstfilesplacedinacanalmustalwaysbepre-curvedwiththesmallestpossibleradius.That
is,all10andK15fileshavetobecurved(thereareinstrumentsspecificallyusedforthispurposebutifyou
don’thavethose,acollegeplierwilldo)atthetipinordertonegotiatearoundthecurvatureofthecanal
andtopreservethatnaturalcurvaturewiththeleastamountoftransportation.Thiscurvingofthetipof
asmallfileisutterlyimportant.Oncethetipofasmallfileiscurved,itisplacedinthecanalandgently
workedwithacircumferentialwatch-windingmotionuntilitisabletoreachtheapex.Itisimportantto
rememberthat,inyourendeavortogettotheapex,thecircumferentialwatch-windingmotionmay
provetobemuchmoreeffectivethanastraightup-and-downfilingmotion.Fornarrowercanals,you
maynotbeabletoreachtheapeximmediately.Thegoalistoworkyourselfdownincrementally
withoutdistortingthecanalanatomy.Whenyouaresuccessfullyworkingyourselfdowntoreachthe
apex,thecanalfeelsstickyandthisisagoodindicationthatyoucancontinuetocarefullyworkyourself
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downtoestablishthelength.Acanalthatnolongerfeelsstickybutfeelslikeahardwallindicatesthat
youcouldbetransportingthecanaloutofitsnaturalcurvature(orafilehadseparated).Ifyounolonger
feelthestickinessofthecanal,backstepforonesecond,takeadeepbreath,anddothefollowingthree
things:openupthecoronalpartofthecanal,irrigatecopiously,andpickupthesmallestfilethatyouhave
available(K6orK8)andagaingiveitasmallcurveatthetip.Placethesmallfileinthecanalwhilekeeping
aneyeonitasK6andK8filesareverydelicateandwillcrimpleeasilyifyouhitanyotherhardsurface
whiletryingtoplacetheminthecanal.Onceitisinthecanal,gentlykeeprotatingthembackandforth
toseeifyoucanfindthestickyspotagain.Virtuallynoapicalpressureisneededwhiledoingthis.Oncea
stickyspotisfound,youmayhavetokeepworkinginthesamemannerwhilefrequentlyirrigating.Again,
thesmallfilescanseparateeasilyinanarrowcanalifhandledcarelessly,anditmaybewisetoinspect
themfrequentlyandtogothroughafewoftheminsteadofusingoneuntilitseparates.
AK15filecurvedwithasmallradiusofcurveatthetip
(left-useful)andwithalargeradiusofcurveatthetip
(right-notasuseful).ALLsmallfiles(6,8,10,15)mustbe
pre-curvedwithasmallradiuscurveatthetip.Afile
shouldnotbebentwithalargeradiuscurveliketheone
shownontherightbecausecurvingafilethiswayhas
onlylimitedbenefits.
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Coronal/OrificeWidening
Howweachievethiscoronalwideningofthecanalhaschangedsomewhatovertheyears.First,the
rationaleforcoronalcanalwidening:Insmallercanals,openingupthecoronalportionofthecanal
allowsyoutoreachtheapexmoreeasily,againwithlesstransportationinthecriticalapical1/3ofthe
canal.Inotherwords,youaremorelikelytopreservethenaturalcanalanatomywhenthecoronal
portionofthecanalhasbeenopenedupfirst.Inlargercanalswhereyouareabletoreachtheapex
easily,orifice/coronalcanalwideningisactuallynotthatsignificant.Itmustbepointedoutthatthegates
gliddenisnolongerroutinelyusedforthispurpose,atleastbytoday’seducators’standards.Therearea
numberofstudiesintheliteraturethatshowedremovingexcessivetoothstructurefromthecoronalpart
ofthecanalcanreducetheresistancetofracture.Obviously,thereisnogoodreasontoremovemore
toothstructurethannecessaryespeciallywhenit’smorelikelytoleadtoamoreadverseoutcome.
Personally,Iseldomusethegatesglidden,andIonlyuse04taperrotaryfiles,evenforcoronalflaring.
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AdvancedTip:Incorporatingsomedegreeof“crown-down”techniquemaygiveyoubetterresultsin
manycases.Iusuallypickupabiggerrotaryfile,suchasa40/04ora35/04file,toinitiatecrown
downformostofmycases.ThisisactuallydoneevenbeforeImeasuremyworkinglength.Knowing
thatthemajorityofrootcanalworkinglengthsfallunder19mm-22mmrange,Iwillusetherotaryina
crown-downfashion,startingwitha40/04andthenusinga35/04anda30/04toabout15-16mms
downthecanal.Imeasuremylengthatthispoint,hand-filealittlebitandthenbegintherotary
instrumentationatfullworkinglength.Thisislistedasanadvancedtipbecauseyouhavetobefully
proficientatdoingRCTsbeforeyoucaneffectivelytakeadvantageofthistechnique.Choosingthe
rightsizerotaryfiletoinitiateyourcrown-downisajudgmentcallasyourinitialfilesizemaybe
differentforeachcase.Youhavetohavebuiltsomespeedintoyourtreatmentsandalsohavetobe
abletoperceivewhentochangetherotaryfiletoasmalleronewhilegoingdownapicallywhenthe
rightamountofresistanceismet.
#19is26mmslong.Workinglengthwasmeasuredaftercoronalhalfofthecanalshavebeenopenedupwithrotaryfiles.
Managementofcurveintheapical1/3wouldhavebeenmuchmoredifficultwithoutfirstinstrumentingthecoronalhalfofthe
canals.
#19and#3RCTcasesondifferentpatients.Notepreservationoftoothstructureandnaturalcanalanatomy.Apreviouslydone#18
showsextensivewideningofthecoronalportionofthecanalswithgatesgliddenandstraighteningofthecanals.#3isaheavily
calcifiedcase.Instrumentationwasdoneusingthecrowndowntechniquealongwithcarefulnegotiatingwithsmallcurvedfiles.
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Instrumentation
Thegeneralruleistohand-instrumenttosizeK15beforeswitchingtorotaryfiles.Oneofthemost
disturbingexperiencesapractitionerdoingaRCTcanhaveistohaveaseparationofafile.Toprevent
thismishapandotheriatrogenicerrors,itisimportanttorememberafewthings.First,alwayshavesome
formoflubricationsuchassodiumhypochloriteorRCPrepinsidethecanal.Continuousinstrumentation
insideadebris-filleddrycanalcanbeamaincauseofallsortsoftroubles.Second,justlikethehandfiles,
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ifyouarenotgettingtothemeasuredlengthinoneattemptwitharotaryfile,thenthelengthshouldbe
attainedincrementally.Thismeansremovingthefilewhenresistanceismet,irrigating,andwipingthe
fileswithanalcohol-soakedgauzetoremovethedebrisstuckintheflutesofthefile.Sometimes
irrationalitycouldtakeoverandwecanpushalittletoohard(It’sFridayafternoon,4:30PMandyouhad
alatestartwiththelastcaseofday)inanattempttoreachtheworkinglengthquickly,butdoingsocan
inevitablyresultinaseparatedfileatsomepoint.
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Oneofthegreatbutlesstalkedaboutbenefitsofamodernendodonticrotaryinstrumentisthat
itremovesdebrisfromthecanalasitrotatesclockwise.Observethefiletoseeifitis
accumulatingtoomuchdebrisintheflutesandwipethemofftopreventgeneratingexcessive
torqueandstress.
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Theeffectofalarge-taperinstrumentisnotawellunderstoodconcept.Wetypicallyassociate
increasedstiffnessanddecreasedflexibilityofarotaryfilewiththeincreaseintipsizeonly.That
is,wesaythatsize30isstifferandlessflexiblethansize25becauseitisbigger,andsize40isless
flexiblethansize35,andsoon.Butincreasingthetaperoftheinstrumentcanalsohavea
dramaticnegativeeffectontheoverallflexibilityoftheinstrument.Thus,an06taperfileis
muchstifferandlessflexiblethanan04taperfile,andbecauseofthatinflexibilityitmaynotbe
abletogetintosomecanalsthatan04taperfileofthesametipsizecan.
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OnEfficientInstrumentation,RPM,andContactTime:Anargumentcouldbemadethatusinga
rotaryfileatahighRPM(>500)isdangerousforlessexperiencedclinicians.Anargumentcould
bemadethatusingarotaryfileatalowRPM(<300)isalsodangerousforlessexperienced
clinicians(whichprobablyindicatesthatwhat’sdangerousistheperson).Itisoftenoverlooked
howusingahigherRPMcandramaticallyincreasethecontacttimeoftheinstrumentwiththe
wallsofthecanal,butthisisanotherimportantconcepttounderstand.Astraightfileinserted
intothecanalwantstostraightenitselfinsideacanal.Thisishowtransportationofthecanal
occurs.Therefore,inordertominimizetransportation,afile’scontacttimewiththewallsof
thecanalshouldbekeptasminimalaspracticallypossible.Thus,whenafilehasdoneitsjobof
reachingtheapex,thecanalshouldbeirrigatedtoremovedebris,andthenextlargerfilesize
mustbeused.Thereisatendencyforlessexperiencedclinicianstorepeatedlyinstrumentthe
canals,overandover.Thishabitisespeciallydeadlywhentherepeatedinstrumentationisdone
underahighRPM,asthemostcommonundesirableoutcomewouldbeeitheraseverely
transportedcanalorablown-outapex.
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InstrumentationSize
Thisisanareaoffiercecontroversyandtherearevaryingopinionsabouthowbigacanalneedstobe
instrumentedto(IoncehadarepfromthelargestdentalproductcompanyintheUSaskmewhyI
instrumentthecanalstocertainsizes).Onethingthatmostendodontistsdoagreeon,however,isthat
theirrigantmustbeabletoreachtheapextoremovedebrisanddisinfectthecanals.Asmallcanal
(instrumentedtosize25/04orsmaller)maynothavetheirrigantreachthecriticalapical1/3ofthecanal
andalsomaybedifficulttofillproperlyinsomecases.Conversely,inaheavilyinfectedrootcanalsystem
itmaybenecessarytoinstrumentthecanalstoabiggersizethanwhenthepulpisstillvital(vitalmeans
sterile).Thefollowingisalistofmyusualinstrumentationsizesasofthiswriting:
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UpperCentrals:45/04or50/04
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UpperLaterals:35/04or40/04(Thistoothhasanapicaldistolingualcurvethatisoftentimes
mismanaged,leadingtomanyfailedtreatments.)
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LowerIncisors:30/04,35/04,or40/04(Consideredthemostdifficulttoothbysomespecialists)
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AllCanines:40/04or45/04
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SingleCanalPremolars:Atleastsize40
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TwoCanalPremolars:30/04or35/04
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MesialCanalsofLowerMolars:30/04or35/04
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DistalCanalsofLowerMolars:40/04or45/04
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MBandDBofUpperMolars:30/04or35/04
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PalatalofUpperMolars:40/04or45/04
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Thisis,ofcourse,alooseguideline.Afinaldecisiononthesizeofinstrumentationismadewhile
thecanalsarebeinginstrumented.Insomerarecases,averylargecanalwithalongstanding
infectionandaresorbedrootendmayhavetobeinstrumentedtoevenhigherthansize50.
Somecanalswithwickedcurvesmaynotbeabletobeinstrumentedtoanythingbiggerthansize
25.Atanyrate,itisimportanttorememberthatthediscussionofapicalsizeshouldbecarried
outalongwithaconsiderationfortheinstrument’staper.Afilewithasize25tipand08taper
wouldbemoreaggressiveinremovingrootdentinthanafilewithasize35tipand04taper.It
mustbenotedthatlargetaperinstruments(06orgreater)removemoredentinfromthecoronal
halfoftheroot,whichunnecessarilyweakenstheroot.
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Anupperlateralincisorwithalongstandinginfection.Thebluntedroottipindicatesrootresorptionandlackofanatural
constrictionattheapex.Size45/04guttaperchashowsthatitmaynotcreateanadequateapicalseal.Thecanalwastakento
size70usingaLightSpeedsystem(0taper,parallelinstrument)andfilledwithamatchingSimpliFillguttaperchaobturator.
Alternatively,theapical1/3ofthecanalcouldhavebeenfilledwithMTA.
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RootFilling/Obturation
Verticalcompactionofguttaperchausingaheatedpluggerandbackfillingwiththermoplasticgutta
perchahasbecomemoreorlessthestandardobturationtechniqueovertheyears.Thebasicpremiseof
thistechniqueisbasedoncreatinga“smallapex”andacontinuouslytapered,flaringcanalusingalarge
taperedinstrument.Thosetwoprinciplesaboutcreatinganapexassmallaspossibleandinstrumenting
thecanalwithacontinuouslytaperedinstrumentrepresentthe“inborn”characteristicsofthisvertical
compactiontechniqueatitsorigin.However,inpastandpresent,thisparticularobturationtechniquehas
hadasomewhatunfortunateinfluenceontheoveralldesignofrotaryinstruments(smalltip,
larger/progressivetaper)inthemarket.Itmustbepointedoutthatthisisprobablytheoppositeofwhat
weshouldbethinking,becauseourfirstpriorityindoingarootcanaltreatmentshouldbeproper
debridinganddisinfectionofthecanals,notfillingtherootsaccordingtothemandatesofaspecific
obturationtechnique.Obturationtechniqueswillevolveandgetmodifiedovertime.Moreover,some
cliniciansmaytakeastandthatitisnotpossibletocreatea“continuouslytaperingfunnel”inallthe
canals.Asstatedbefore,thesizeofinstrumentationremainsanareaofopendiscussion,butwhat
everybodyagreesonisthefactthatbyinstrumentingthecanalswemustcreateastoporaboxjustshort
oftheapicalconstriction.Let’slookatsomeofthetechniquesthatmayfacilitatetherootfillingprocess.
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Overuseofthesealercanmakethingsmoredifficult.Itshouldberememberedthatexcess
sealerjustcomesbackoutduringbackfillingwithguttapercha,makingthingsmessier,especially
whenalargeamountofsealerisallmuddledupwiththermoplasticguttapercha.
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Thesealercanalsobeplacedinthecanalbeforeconeplacementeitherwithafileorwitha
smallersizeguttapercha,butthisisnotmandatory.Then,asmallamountofsealercouldbe
placedonthe3-4mmtipoftheguttaperchaconeandplacedinthecanal.
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Anypastetypematerial,suchasthesealerorcalciumhydroxidepasteusedasinter-appointment
medicament,canbeplacedinthecanalbyrotatingafileinacounterclockwisemotion.
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Rememberthatthedefaultclockwiserotationofarotaryfileremovesdebrisupandoutofthe
canal.
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Treattheguttaperchaconewithcarewhileplacingitinthecanalwithacollegepliertomake
surethatthetipdoesn’tgetfoldedover.Keepaneyeonthetipuntilitdisappearsintothe
orifice.Then,usingyourfingers,gentlyrotatetheconebackandforthuntilitadvancesallthe
waytoworkinglength.Strictlyusingaverticallydirectedmotionwithoutanyrotationmay
preventtheguttaperchaconefromseatingallthewayinsomecanals.
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Twocanalsthatjoin:Separatelyplacingaguttaperchaconeineachcanalwillallowittoadvance
toworkinglength,butwhenplacedtogether,thefirstconewillpreventthesecondconefrom
gettingtolength.Thishappensfrequentlyinthetwomesiobuccalsofmaxillarymolars,thetwo
mesialsofthemandibularsecondmolars,upperpremolars,andlowerincisors.Youmayalsoget
ahintofthisparticularanatomyifyouarelookingattheorificeswithahigh-powered
magnificationwhiledryingthecanals,asyoumaybeabletonoticethefluctuationofirrigantin
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the2 canalwhilethe1 canalisbeingdriedwithapaperpoint.Placethefirstconeinthecanal
thatisassumedtobelargerorstraighter(e.g.,inMB1beforeMB2inuppermolars,inthepalatal
beforethebuccalinupperpremolars,inthemesiolingualbeforethemesiobuccalinmandibular
nd
st
molars).Now,searoffthe2 conethatisnotreachingtheapexfirst,thenburnoffthe1 cone
st
thatwasinitiallyplacedtolength.Insummary,thestepsareasfollows:Placethe1 coneto
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nd
st
length,placethe2 conetojoininglevel,burnoffthe2 cone,thenburnoffthe1 cone.
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Oneofthemorefrequentlyaskedquestionsinregardtoobturationisaboutfillingthecanals
thatbranchinto2ormorecanalsfurtherapically.Forallintentsandpurposes,stronglyconsider
referringthesecasestoaspecialist.Thelevelofdifficultyisexceedinglyhighinsomecases,
especiallywhenonecanalbranchesoutatasharpangle,andpropermanagementmayonlybe
possibleundertheuseofamicroscope.
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Help!Myguttaperchadoesn’tgotomyworkinglength!Sometimeswerealizethatdespite
havingfullycompletedtheinstrumentation,theguttaperchaconedoesn’tfitallthewayto
workinglength.Thereareanumberofpossibleexplanationsforthis,butwhateveryoudo,resist
thetemptationtofillit3mmsshortandmaketheall-too-commondefensivestatement—Well,
myapexlocatortoldmethatthatwastheworkinglength.Itneedstobepointedoutthatthe
canalconstrictionisshortoftheradiographicapexandinsomecasestherootfillingcouldlooka
littleshort.Yet,iftheapexlocatorinitiallyindicatedthattheworkinglengthwas20mms,andifI
filleditto18mms,thenthemachinemostcertainlydidnottellmethat18mmswasthelength.
What’sresponsibleforthatdiscrepancyisthehumanerrorinproperexecution.Let’slookat
someofthereasonswhyaguttaperchaconemaynotgofullytoworkinglength:
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Debrisinthecanal:Afilemaystillgotoworkinglengthinpresenceofsomedebris
becauseitismetal,butasoftguttaperchaconemaynot.Hittheapexonemoretime
withthelargestrotaryfileyouused(wipethefilecleanbeforeyoudothis)andthen
irrigatethecanalonemoretime.
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Discrepancyinmanufacturing:Ifyoutook5differentbrandsofguttaperchaand
comparedtheexacttipsizeusingagauge,thenitwouldshowusthatsomebrandsof
guttaperchaarebiggerorsmallerthantheothers.Now,ifyouopenedupapacketof
guttaperchafromonebrandandthencomparedtheguttaperchaconesinthatpacket,
youarestilllikelytogetsomediscrepancyinsizedespitetheconesbeingmadebythe
samemanufacturer.Atanyrate,ifoneconedoesnotfittoyourdesiredlength,try
anotheroneofthesamesizeorasmallersize(whichmayhavetobemodified).
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Usingastrictlyverticalmotiontoplacethecone:Asexplainedbefore,incorporatea
rotatingmotionwhenplacingtheguttapercha.
Ifyourgoalwastoinstrumentacanaltoacertainsize,andiftheguttaperchaconestopsalittle
short,thenyoucanalsotryinstrumentingthatcanalwithafileonesizelargertoabout0.5mm1mmshortoftheworkinglength.Iactuallydothisroutinelywithsmallercanals.Forexample,if
Iintendedtofillthemesialcanalsofalowermolarwithsize30/04guttaperchaconesandthe
workinglengthis20mms,thenIwouldinstrumentthecanalswithasize30/04rotarytolength
andthenwithasize35/04toabout19or19.5mms.Usingthistechnique,theconewilladvance
righttotheworkinglengthandstillgiveyouasolidtugbackmostofthetime.
AFINALWORD
BackinthedayswhenIwasadentalstudent,arespectableperiodontistwhowastheheadoftheperiodontics
departmenthadsaidsomethingthatIremembertothisday—thathedidn’tlearntoSRPuntil2yearsafterhe
becameaperiodontist.ThisstatementwassostrikingtomethatIstillrememberthetoneoftheprofessor’s
voicewhenhesaidit.Not2yearsafterhegraduateddentalschool,but2yearsafterhebecameaspecialist.
Myperspectiveabouttheendodonticspecialtyissimilar.AndIsaythisnottomakeitseemlikelearning
aboutrootcanalsisadauntingtask,butasareminderthatcontinuouslylearningtoimproveyourselfand
puttingintheeffortcanresultinalevelofproficiencythataddslayersofsatisfactiontoyourpracticeof
dentistry.IfyoucontinuetodoRCTsinyourpractice,youareboundtohavedifficultandfrustratingcasesat
somepoint.Butgettingbetteratanythingworthwhileisahumblingexperiencebecauseitgoeshandinhand
withfailure.Itisonlyhumantobediscouragedbytheseexperiences,butthemostimportantthingistosee
whatcouldbelearnedfromthesechallengingcases.Standup,dustyourselfoff,anddon’tstopdoingyour
carefullyselectedcases.Iwishyouthebestofluck!