牙体牙髓英文版课件：ROOT CANAL PREPARATION

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1、ROOT CANAL PREPARATIONRATIONALEMicrobiology Apical periodontitis is caused by microbialinfection of the root canal system.Successfultreatment is dependent on the control of thismicrobial infection.An understanding of themicrobiology of apical periodontitis is a pre-requisite for effective treatment.

2、The General Microbial Flora With the development of anaerobic culturing techniques and sampling methods an insight into the microbial flora of infected root canals has become possible.Nowadays there are sophisticated techniques for identification of bacteria that do not rely on culturing methods.Ind

3、eed some bacteria that can be identified by genetic techniques are non-cultivable.Apical periodontitis is typically a poly microbial infection dominated by obligately anaerobic bacteria.Rationale for Root Canal Preparation mechanical means chemical binationACCESS CAVITY PREPARATIONPulp chamber roof

4、Pulp hornRoot canal orificeApical foramenPulp chamber floorPulp chamberRoot canalRoot canal systemMajor anatomic components of the root canal system Preoperative RadiographThere is an old cliche that Access is Success.A preoperative radiograph should normally betaken using a paralleling device,as th

5、is produces an image that is almost actual size.The radiograph must show the entire tooth and at least 2 mm of bone surrounding the root apices.Principles of the Paralleling Technique The film packet is placed in a holder in the same plane as the long axis of the tooth.The tube-head is then aimed at

6、 a right angle to the tooth and film packet using an aiming device.A holder should be used to help align the X-ray film and beam.Panoramic&Cephalometric X-Ray Unit口腔曲面断层全景X线CBCT(the abbreviated form of)Cone beam CT 锥形束CTA good-quality radiograph of the mandibular first molar which requires root cana

7、l treatment.number of roots,size of pulp chamber,fit of coronal restoration,caries,pulp stones,curvature ofroot canals,likelihood of lateral canals,Iatrogenic damage(perforations and fractured instruments).The objectives of access cavity preparation are to:The pulp chamber can be debrided.Enable the

8、 root canals to be located Providing direct straight line access to the apical third of the root canalsEnable a temporary seal to be placed securelyConserve as much sound tooth tissue as possibleHow?Location of Access CavityThe Lid-off Approach to Access Cavity1.Estimate length2.Penetrate to the pul

9、p chamber3.Lift off the roof with a bur in a pulling action4.Refine the access cavity.Preoperative carious exposureDome-ended fissurebur is used to penetratepulp chamberRoof of pulp chamber removed with roundburNon end-cuttingbur is used to lift lid of pulp chamber and refine cavityEstimating the De

10、pthThe depth of the roof of the pulp chamber can be estimated from the preoperative radio-graph.FG:标准形状标准形状 RA/CA:弯头弯头 HP:低速车针低速车针nonend-cutting burDiamendo：是锥形金刚砂钻针，顶端为圆钝球形，无切削作用，：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孔，预备的髓腔壁剖面更完整long shank low-speed ro

11、und burThe pulp floor mapendodontic explorerAn endodontic probe(e.g.DG16,Hu Friedy,Chicago,IL,USA)is a double-endedlong probe designed for the exploration of the pulp floor and location of root canal orifices.A long-shanked excavator may also be helpful for removing small calcifications and obstruct

12、ions when locating canals.Troubleshooting Access Cavity PreparationCalcifications Pulp stones and irritation dentine formed in response to caries and/or restorations may make the location of root canal orifices difficult.Special tips for ultrasonic handpieces are invaluable in this situation,as they

13、 allow the precise removal of dentine from the pulp floor with minimal risk of perforation.In the absence of a special tip a pointed ultrasonic sealer tip can be used to remove pulp stones from the pulp chamberAn ultrasonic tip for removal of dentine on the pulp floorSclerosed Canals Illumination an

14、d magnification are vital for the location of Sclerosed root canals.The endodontist would use a surgical microscope.while a general dental practitioner might have loupes and a headlight available.Loupes give excellent magnification and illuminationUnusual AnatomyGood radiographic technique should al

15、ert the practitioner to unusual anatomy,such as C-shaped canals.The C-shaped canal may have the appearance of a fused root with very fine canals.If confronted with a pulp chamber that looks unusual the dentine areas on the pulp floor map should give some idea of the location of root canals,and of th

16、e relationship of the floor to surrounding tooth structure.The Location of Extra CanalsThe second mesiobuccal canal of maxillary molarsThere is a second mesiobuccal canal in approximately 60%of maxillary molars.Location of the second mesiobuccal canal in the maxillary first molarit often lies under

17、a lip of dentine on the mesial wall of the access cavity A lip of dentine has been removed using a round bur to uncover the two mesiobuccal canals(arrowed)in this maxillary molar.Four canals in mandibular molars:Four canals are found in approximately 38%of mandibular molars.If the distal canal does

18、not lie in the midline of the tooth,then a second distal canal should be suspected.The canals are often equidistant from the midline.Distal canal orifices lieequidistant to midlineLocation of a second distal canal in the mandibular first molar.Two canals in mandibular incisors The incidence of two c

19、anals in lower incisors may be as high as 41%.A common reason for failure of root canal treatment in these teeth occurs when a second canal has not been located and is consequently not cleaned.Canals may be missed owing to incorrect positioning of the access cavity.If access is prepared too far ling

20、ually then it may be impossible to locate a lingual canal.To gain entry into a lingual canal the access cavity may sometimes need to be extended very near to the incisal edge.Two canals in a mandibular premolar The highest reported incidence of two canals in mandibular premolars is 11%.There are rar

21、ely two orifices.The lingual canal normally projects from the wall of the main buccal canal at an acute angle.It can usually be located by running a fine(ISO 08 or 10)file with a sharp bend in the tip along the lingual wall of the canal.PREPARATION TECHNIQUESThe aims of root canal preparation are:To

22、 remove infected debris from the root canal system To shape the canal allowing thorough dis-infection with irrigants and intracanal medication To provide a space for the placement of a root canal filling.The filling material should ideally seal the entire root canal system from the periodontal tissu

23、es and oral cavity.TerminologyCrown-down PreparationThe root canal system of a tooth can be prepared to give a tapered preparation in essentially two ways:apical to coronal or coronal to apical.Preparation of the coronal part of the root canal first has several significant advantages.Procedural Erro

24、rsTransportation Transportation results from the selective removal of dentine from the root canal wall in a specified part.In cross-section the central point of the canal will have moved laterally.Transportation can be carried out electively(during coronal flaring to straighten the canal),or may occ

25、ur as an iatrogenic error resulting from the incorrect use of hand instruments.Internal transportation is used to describe the movement of the canal system internally.External transportation occurs when the canal is over-prepared and the apical foramen is enlarged or moved;often the foramen becomes

26、a tear-drop shape.Elbows and zips are caused by the file attempting to straighten in the root canal as it is worked up and down.Filing produces acanal that takes on an hourglass shape,with the narrowest cross-sectional area at the elbow and with the canal widening into the zipped region further apic

27、ally.The resultant space is difficult to clean and obturate.Strip PerforationStrip perforation occurs in the middle part of the inner curve of a root canal if excessive dentine is removed during preparation.This may be a result of relatively large and stiff files attempting to straighten within the

28、root canal,or of over-use of GatesGlidden burs or orifice shapersBalanced Force The balanced force action when used with flexible files results in a more centred preparation and less transportation than with a filing technique.The technique(Roane et al 1985)This instrumentation technique uses clockw

29、ise/anticlockwise rotational motion to remove dentine with flexible stainless steel files or nickel-titanium files.It is useful for rapidly removing dentine in curved canals whilst maintaining curvature(files are not precurved).Using Greater Taper Files for Apical PreparationGreater Taper files are

30、manufactured from nickel-titanium and have to be used with a reverse balanced force action.To prevent the tip binding and possibly fracturing it is important to prepare a pilot channel(glide path)for the instruments to follow.The canal is instrumented to the working length using a balanced force act

31、ion with Flexofiles to at least a size 25.Greater Taper files can then be worked to the same length instead of stepping back with multiple instruments.Greater Taper hand files:white 0.06,yellow 0.08,red 0.10,blue 0.12.Tapers appropriate for various root canal situationsMerging The apical and coronal

32、 preparation should merge into one another in a gradual smoothtaper.This can often be achieved with a single Greater Taper instrument,as opposed to stepping back with multiple instruments.Crown-down Preparation TechniquesThe following crown-down hand preparationtechniques are described:Stepdown Modi

33、fied Double FlareStepdown Technique of Canal Preparation(A hand-filing technique with precurved files:Goerig et al(1982).)Precurving Files Files can be easily and accurately precurvedin a file-bending device.The curveis estimated from the radiograph,and by feedback from small files that are placed i

34、n the canal at the start of treatment.Initial Coronal Flare Apical Preparation Apical Flare(Stepback)ArmamentariumArmamentariumStainless steel size 10 K-files Used to explore canal patency Filing or quarter turn pull motion Do not rotate through 360 degreesArmamentariumStainless steel size 15 and 20

35、 K files Used to establish actual working lengthArmamentariumArmamentariumProfile orifice shapers Used to prepare the coronal one third of the root canalProfile Orifice ShapersArmamentariumProfile 0.06 taper rotary files Used to prepare the middle thirdArmamentariumArmamentariumProfile 0.04 taper ha

36、nd NiTi files Used to prepare the apical third of the root canal The Modified Double-Flare Technique A technique that uses the balanced force Coronal Preparation Preparation of the Apical Section Apical Flaring instrumentation action:Saunders(1992)改良双敞技术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：敞开根管冠部；根尖部预

37、备；逐步后退技术预备根管中段；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。临床英语会话临床英语会话 At the registration挂号挂号 1.What can I do for you?2.What is wrong with you?3.Do you want to see a dentist?4.Which speciality do you want to register with?您要挂哪个科的号？5.Do you want to have your tooth pulled(tooth

38、filled)?您要拔牙补牙吗？6.For a filling?A denture?Or a cleaning?补牙？镶牙？还是洁牙？7.Is this your first visit to this dental clinic?8.May I have your address,telephone number,age and occupation,please?请告诉我您的地址，电话号码，年龄，职业。9.Please write your name and date of birth on this card.10.Please fill out this record card.请填写

39、这张记录卡。11.Do you have a registration card?您有挂号证吗？12.When did you come last?13.Do you have an appointment?您有预约吗？14.We are fully booked today.今天已经约满了。15.Please show this card at the registration desk every time you come.每次来挂号，请出示这张卡 16.Please pay for the registration.请交挂号费。17.Here is your receipt and c

40、hange.这是收据和找回的零钱。18.This is your registration card.Please dont lose it and bring it here whenever you come.这是您的挂号证，请不要遗失，每次来时带着它。19.Please wait in the waiting room.请在候诊室等。20.The doctor will see you soon.21.The doctor now is with a patient.22.Your turn is next.23.There are two more patients before yo

41、u.24.The patient before you is a rather complicated case,Im sorry you will have to wait at least half an hour.前面那个病人比较复杂，您至少还得等半小时。25.Please come into the treatment room,will you?请进治疗室。Directions for the position,manner and action 椅位，方式和行为的指导椅位，方式和行为的指导 1.Please sit down in this chair.2.I will lean

42、the chair back.我把牙椅向后倾斜点。3.I will bring the chair up.我将抬高牙椅。4.Please slide up/down the chair.5.Are you comfortable in this position?6.I will place an apron on you.我给您系上胸巾。7.Please lift your head.8.Please turn your head to the right/left.9.Please tuck your chin.请收下颌。10.Please open your mouth a litter

43、 wider.11.Please keep your mouth open.12.Bite down,please.请咬合。13.Tap your back teeth together.请咬后牙。14.Move your jaw to the right and left.请左右错颌。15.Slide your lower jaw forward.向前伸下颌。16.Please keep the teeth together.请保持咬合状态。17.Relax and make yourself comfortable.放松自己，使自己感觉舒服。18.Please relax your tongue/jaw/shoulders.放松舌头/下巴/肩膀。19.Please raise your left hand if you feel pain.如果疼痛，请举起您的左手。20.Rinse your mouth,please.请漱口。