牙体牙髓英文版课件：ROOT CANAL PREPARATION

ROOTCANALPREPARATIONRATIONALEMicrobiologyApicalperiodontitisiscausedbymicrobialinfectionoftherootcanalsystem.Successfultreatmentisdependentonthecontrolofthismicrobialinfection.Anunderstandingofthemicrobiologyofapicalperiodontitisisapre-requisiteforeffectivetreatment.TheGeneralMicrobialFlora

Withthedevelopmentofanaerobicculturingtechniquesandsamplingmethodsaninsightintothemicrobialfloraofinfectedrootcanalshasbecomepossible.Nowadaystherearesophisticatedtechniquesforidentificationofbacteriathatdonotrelyonculturingmethods.Indeedsomebacteriathatcanbeidentifiedbygenetictechniquesarenon-cultivable.Apicalperiodontitisistypicallyapolymicrobialinfectiondominatedbyobligatelyanaerobicbacteria.RationaleforRootCanalPbinationACCESSCAVITYPREPARATION

5PulpchamberroofPulphornRootcanalorificeApicalforamenPulpchamberfloorPulpchamberRootcanalRootcanalsystemMajoranatomiccomponentsoftherootcanalsystemPreoperativeRadiographThereisanoldcliche’that

'AccessisSuccess'.Apreoperativeradiographshouldnormallybetakenusingaparallelingdevice,asthisproducesanimagethatisalmostactualsize.Theradiographmustshowtheentiretoothandatleast2mmofbonesurroundingtherootapices.PrinciplesoftheParallelingTechniqueThefilmpacketisplacedinaholderinthesameplaneasthelongaxisofthetooth.Thetube-headisthenaimedatarightangletothetoothandfilmpacketusinganaimingdevice.AholdershouldbeusedtohelpaligntheX-rayfilmandbeam.Panoramic&CephalometricX-RayUnit口腔曲面断层全景X线CBCT(theabbreviatedformof)ConebeamCT锥形束CTAgood-qualityradiographofthemandibularfirstmolarwhichrequiresrootcanaltreatment.numberofroots,sizeofpulpchamber,fitofcoronalrestoration,caries,pulpstones,curvatureofrootcanals,likelihoodoflateralcanals,Iatrogenicdamage(perforationsandfracturedinstruments).Theobjectivesofaccesscavitypreparationareto:Thepulpchambercanbedebrided.EnabletherootcanalstobelocatedProvidingdirectstraightlineaccesstotheapicalthirdoftherootcanalsEnableatemporarysealtobeplacedsecurelyConserveasmuchsoundtoothtissueaspossible17How?LocationofAccessCavityTheLid-offApproachtoAccessCavity1.Estimatelength2.Penetratetothepulpchamber3.Liftofftheroofwithaburinapullingaction4.Refinetheaccesscavity.PreoperativecariousexposureDome-endedfissureburisusedtopenetratepulpchamberRoofofpulpchamberremovedwithroundburNonend-cuttingburisusedto'liftlid'ofpulpchamberandrefinecavityEstimatingtheDepthThedepthoftheroofofthepulpchambercanbeestimatedfromthepreoperativeradio-graph.FG:标准形状

RA/CA:

弯头

HP:低速车针nonend-cuttingburDiamendo：是锥形金刚砂钻针，顶端为圆钝球形，无切削作用，

不仅能够去除牙本质肩领，还可以有效防止髓腔壁穿

孔，预备的髓腔壁剖面更完整longshanklow-speedroundburThepulpfloormapendodonticexplorerAnendodonticprobe(e.g.DG16,HuFriedy,Chicago,IL,USA)isadouble-endedlongprobedesignedfortheexplorationofthepulpfloorandlocationofrootcanalorifices.Along-shankedexcavatormayalsobehelpfulforremovingsmallcalcificationsandobstructionswhenlocatingcanals.TroubleshootingAccessCavityPreparationCalcificationsPulpstonesandirritationdentineformedinresponsetocariesand/orrestorationsmaymakethelocationofrootcanalorificesdifficult.Specialtipsforultrasonichandpiecesare

invaluableinthissituation,astheyallowthepreciseremovalofdentinefromthepulpfloorwithminimalriskofperforation.IntheabsenceofaspecialtipapointedultrasonicsealertipcanbeusedtoremovepulpstonesfromthepulpchamberAnultrasonictipforremovalofdentineonthepulpfloorSclerosedCanals

IlluminationandmagnificationarevitalforthelocationofSclerosedrootcanals.Theendodontistwoulduseasurgicalmicroscope.whileageneraldentalpractitionermighthaveloupesandaheadlightavailable.LoupesgiveexcellentmagnificationandilluminationUnusualAnatomyGoodradiographictechniqueshouldalertthepractitionertounusualanatomy,suchasC-shapedcanals.TheC-shapedcanalmayhavetheappearanceofafusedrootwithveryfinecanals.Ifconfrontedwithapulpchamberthatlooksunusualthedentineareasonthepulpfloormapshouldgivesomeideaofthelocationofrootcanals,andoftherelationshipofthefloortosurroundingtoothstructure.TheLocationof`Extra'CanalsThesecondmesiobuccalcanalofmaxillarymolarsThereisasecondmesiobuccalcanalinapproximately60%ofmaxillarymolars.LocationofthesecondmesiobuccalcanalinthemaxillaryfirstmolaritoftenliesunderalipofdentineonthemesialwalloftheaccesscavityAlipofdentinehasbeenremovedusingaroundburtouncoverthetwomesiobuccalcanals(arrowed)inthismaxillarymolar.Fourcanalsinmandibularmolars:

Fourcanalsarefoundinapproximately38%ofmandibularmolars.Ifthedistalcanaldoesnotlieinthemidlineofthetooth,thenaseconddistalcanalshouldbesuspected.Thecanalsareoftenequidistantfromthemidline.DistalcanalorificeslieequidistanttomidlineLocationofaseconddistalcanalinthemandibularfirstmolar.TwocanalsinmandibularincisorsTheincidenceoftwocanalsinlowerincisorsmaybeashighas41%.Acommonreasonforfailureofrootcanaltreatmentintheseteethoccurswhenasecondcanalhasnotbeenlocatedandisconsequentlynotcleaned.Canalsmaybemissedowingtoincorrectpositioningoftheaccesscavity.Ifaccessispreparedtoofarlinguallythenitmaybeimpossibletolocatealingualcanal.Togainentryintoalingualcanaltheaccesscavitymaysometimesneedtobeextendedveryneartotheincisaledge.TwocanalsinamandibularpremolarThehighestreportedincidenceoftwocanalsinmandibularpremolarsis11%.Therearerarelytwoorifices.Thelingualcanalnormallyprojectsfromthewallofthemainbuccalcanalatanacuteangle.Itcanusuallybelocatedbyrunningafine(ISO08or10)filewithasharpbendinthetipalongthelingualwallofthecanal.PREPARATIONTECHNIQUESTheaimsofrootcanalpreparationare:•Toremoveinfecteddebrisfromtherootcanalsystem•Toshapethecanalallowingthoroughdis-infectionwithirrigantsandintracanalmedication•Toprovideaspacefortheplacementofarootcanalfilling.Thefillingmaterialshouldideallysealtheentirerootcanalsystemfromtheperiodontaltissuesandoralcavity.TerminologyCrown-downPreparationTherootcanalsystemofatoothcanbepreparedtogiveataperedpreparationinessentiallytwoways:apicaltocoronalorcoronaltoapical.Preparationofthecoronalpartoftherootcanalfirsthasseveralsignificantadvantages.ProceduralErrorsTransportation

Transportationresultsfromtheselectiveremovalofdentinefromtherootcanalwallinaspecifiedpart.Incross-sectionthecentralpointofthecanalwillhavemovedlaterally.Transportationcanbecarriedoutelectively(duringcoronalflaringtostraightenthecanal),ormayoccurasaniatrogenicerrorresultingfromtheincorrectuseofhandinstruments.Internaltransportationisusedtodescribethemovementofthecanalsysteminternally.Externaltransportationoccurswhenthecanalisover-preparedandtheapicalforamenisenlargedormoved;oftentheforamenbecomesatear-dropshape.Elbowsandzips

arecausedbythefileattemptingtostraightenintherootcanalasitisworkedupanddown.Filingproducesacanalthattakesonanhourglassshape,withthenarrowestcross-sectionalareaattheelbowandwiththecanalwideningintothezippedregionfurtherapically.Theresultantspaceisdifficulttocleanandobturate.StripPerforationStripperforationoccursinthemiddlepartoftheinnercurveofarootcanalifexcessivedentineisremovedduringpreparation.Thismaybearesultofrelativelylargeandstifffilesattemptingtostraightenwithintherootcanal,orofover-useofGatesGliddenbursororificeshapersBalancedForceThebalancedforceactionwhenusedwithflexiblefilesresultsinamorecentredpreparationandlesstransportationthanwithafilingtechnique.Thetechnique(Roaneetal1985)Thisinstrumentationtechniqueusesclockwise/anticlockwiserotationalmotiontoremovedentinewithflexiblestainlesssteelfilesornickel-titaniumfiles.Itisusefulforrapidlyremovingdentineincurvedcanalswhilstmaintainingcurvature(filesarenotprecurved).UsingGreaterTaperFilesforApicalPreparation

GreaterTaperfilesaremanufacturedfromnickel-titaniumandhavetobeusedwithareversebalancedforceaction.Topreventthetipbindingandpossiblyfracturingitisimportanttoprepareapilotchannel(glidepath)fortheinstrumentstofollow.ThecanalisinstrumentedtotheworkinglengthusingabalancedforceactionwithFlexofilestoatleastasize25.GreaterTaperfilescanthenbeworkedtothesamelengthinsteadofsteppingbackwithmultipleinstruments.Greater

Taper

hand

files:

white

0.06,

yellow

0.08,

red

0.10,blue

0.12.Tapers

appropriate

for

various

root

canal

situationsMerging

Theapicalandcoronalpreparationshouldmergeintooneanotherinagradualsmoothtaper.ThiscanoftenbeachievedwithasingleGreaterTaperinstrument,asopposedtosteppingbackwithmultipleinstruments.Crown-down

PreparationTechniquesThe

following

crown-down

hand

preparationtechniques

are

described:

Stepdown

Modified

Double

FlareStepdownTechniqueofCanalPreparation

(Ahand-filingtechniquewithprecurvedfiles:Goerigetal(1982).)PrecurvingFiles

Filescanbeeasilyandaccuratelyprecurvedinafile-bendingdevice.Thecurveisestimatedfromtheradiograph,andby

feedbackfromsmallfilesthatareplacedin

thecanalatthestartoftreatment.Initial

Coronal

FlareApical

PreparationApical

Flare

(Stepback)ArmamentariumArmamentariumStainlesssteelsize10K-filesUsedtoexplorecanalpatencyFilingorquarterturnpullmotionDonotrotatethrough360degreesArmamentariumStainlesssteelsize15and20KfilesUsedtoestablishactualworkinglengthArmamentariumArmamentariumProfileorificeshapersUsedtopreparethecoronalonethirdoftherootcanalProfileOrificeShapersArmamentariumProfile0.06taperrotaryfilesUsedtopreparethemiddlethirdArmamentariumArmamentariumProfile0.04taperhandNiTifilesUsedtopreparetheapicalthirdoftherootcanalTheModifiedDouble-FlareTechniqueA

technique

that

uses

the

balanced

forceCoronal

PreparationPreparation

of

the

Apical

SectionApical

Flaring

instrumentationaction:Saunders(1992)改良双敞技术弯曲根管预备方法.改良双敞技术与NiTiflex基本步骤：①敞开根管冠部；②根尖部预备；③逐步后退技术预备根管中段；④器械尖端无切削作用，平衡力切削。NiTi器械的优点：具有优良的抗扭断性；柔韧性为SS器械的2-3倍。超弹性；生物相容性；抗腐蚀性。临床英语会话

Attheregistration挂号1.WhatcanIdoforyou?2.Whatiswrongwithyou?3.Doyouwanttoseeadentist?4.Whichspecialitydoyouwanttoregisterwith?您要挂哪个科的号？5.Doyouwanttohaveyourtoothpulled(toothfilled)?您要拔牙补牙吗？6.Forafilling?Adenture?Oracleaning?补牙？镶牙？还是洁牙？7.Isthisyourfirstvisittothisdentalclinic?8.MayIhaveyouraddress,telephonenumber,ageandoccupation,please?请告诉我您的地址，电话号码，年龄，职业。9.Pleasewriteyournameanddateofbirthonthiscard.10.Pleasefilloutthisrecordcard.请填写这张记录卡。11.Doyouhavearegistrationcard?您有挂号证吗？12.Whendidyoucomelast?13.Doyouhaveanappointment?您有预约吗？14.Wearefullybookedtoday.今天已经约满了。15.Pleaseshowthiscardattheregistrationdeskeverytimeyoucome.每次来挂号，请出示这张卡16.Pleasepayfortheregistration.请交挂号费。17.Hereisyourreceiptandchange.这是收据和找回的零钱。18.Thisisyourregistr