Devitalization of pulp: indications to application, methods, medicines

15. Devitalized method of pulpitis ntreatment: indications to application, methods, medicines. Devitalized extirpation and amputation of npulp and combined methods of pulpitis treatment. Indications, stages of ntreatment, nowadys technologies. Complications and their removal. Effectivity nof the method.

 

OPENING THE PULP CHAMBER AND CANALS

 

After  the  tooth  is  isolated,  the  dentist  makes  an opening through the crown of the tooth to gain access to  the  pulp  chamber  and  canal.  The  opening  is  made through the lingual surface on anterior nteeth (fig. 7-16, A) and through the occlusal surface on posterior nteeth (fig.  7-16,  B).  nFriction-grip  and  latch-type  burs  or diamond  stones  are  used  to  create  the  endodontic opening. Sizes vary according nto the preference of the dentist and the size of the chamber and canals of the tooth.

REMOVING  THE  PULP

 

After the endodontic opening is made, the dentist nwill  locate  the  nroot  canals  and  nremove  the  pulp.

Anterior  nteeth  usually  have  none  root  canal,  nbut  often lower  incisors  nwill  have  two  ncanals.  Posterior  teeth may  nhave  up  to  nfour  canals  of  ndifferent  sizes.

Anatomical variations exist among patients; therefore, nadditional  canals  may  nbe  found.  A  nthin,  straight explorer  can  nbe  used  as  na  probe  to  nlocate  canal openings  within  nthe  pulp  chamber.  nThe  larger  pulp canals are easier to locate; whereas, nsmaller canals are sometimes difficult to locate.

Once the canals are located, the pulp tissue must nbe removed.  If  the  npulp  tissue  is  nstill  intact,  the  nthin, flexible, barbed broach is used to remove it. Broaches are  considered  ndisposable  and  should  nbe  discarded after  one  nuse,  since  they  nare  subject  to  nfracture  after repeated   sterilization.   If   nthe   pulp   tissue   nhas disintegrated, it is simply removed when the canal is cleaned and nfilled.

 

Direct Pulp Capping with MTA

 

MECHANICAL pulpal exposure is inevitable when one nexcavates a large carious lesion.  If the ntooth is pretty much broken down and requires a crown, then root canal therapy nshould be done.  But what would you do if nthe tooth were asymptomatic with a lot of tooth structure left before the nexcavation?  Would you attempt to do a ndirect pulp cap to avoid root canal therapy for the patient?  What pulp capping material should you use and nhow should you proceed?

     I was ntaught in dental school to do direct pulp capping in primary teeth.  When it came to permanent adult teeth, I was ntold not to bother because the success rate was low unless the permanent was ia young person with incomplete root formation. In that case, direct pulp ncapping should be done in the hope that apexification would continue.

     Many articles have been written about pulp ncapping with MTA.  Tziafas et al did a nstudy to determine the early pulpal cell response after capping application of nMTA in mechanically exposed pulps.  “A nhomogeneous zone of crystalline structures was initially found along the npulp-MTA interface, while pulpal cells showing changes in their cytological and nfunctional state were arranged in close proximity to the crystals.  Deposition of hard tissue of osteotypic form nwas found in all teeth in direct contact with the capping material and the nassociated crystalline structures.  nFormation of reparative dentine was consistently related to a firm nosteodentinal zone.”  Aeinehchi et al nfound that pulp capped with MTA “demonstrated less inflammation, hyperaemia and nnecrosis plus thicker dentinal bridge and more frequent odontoblastic layer nformation than calcium hydroxide.”  nMoghaddame-Jafari et al found that MTA induces proliferation and not napoptosis of pulp cells in vitro.  And nChacko and Kurikose found that pulps capped with MTA showed dentin bridge nformation which was more homogeneous and continuous with the original dentiwhen compared to the pulps capped with calcium hydroxide.  All these studies suggest that MTA is a good nmaterial to use for direct pulp capping.

     A 43-year-old gentleman came in to see me non a Saturday morning regarding a large carious lesion on the mesial of tooth # n15.  (See Figure 1.)  He said that he would be out of the country nfor three months and was worried that the tooth might blow up on him.  Examination showed that the tooth was nasymptomatic and vital.  The x-ray showed nthat there was a little bit of dentin separating the caries from the pulp.  I excavated the decay using the # 8 round bur non a slow-speed handpiece.  There was a nlittle bit of pink showing by the time I removed all the decay.  I went in and removed a little bit of the npulp horn to make sure that all the infected pulp, if any, had beeremoved.  I irrigated the area with 2 npercent lidocaine to remove the debris.  nI then mixed a little bit of MTA into a putty and applied it on top of nthe pulp.  I used a moist cotton pellet nto condense the MTA and also to remove some of the moisture.  The cavity was closed with zinc phosphate ncement.  (See Figure 2.)

 

The patient was supposed to come back for an evaluation when he returned nfrom his trip.  That was back in January nof 2002.  He finally did come back oNovember 10, 2006, for a root canal on a different tooth.  I took an x-ray of # 15 at that time and saw nthat  there was now a thick layer of ndentin bridge right below the MTA (Figure 3).  nThere was no sensitivity to percussion, palpation, or chewing.  The pulp was vital to the Endo Ice test with nno inflammation.  The only problem was nthat it had a large open contact space.  nI might have been lucky with the successful pulp capping in this case or nmaybe MTA is the next best thing.  The nonly other direct pulp capping I did on an adult was on one of the dentists iour office.  He had extensive decay, and nthe tooth was angulated so that access and proper isolation were very ndifficult.  I did a pulpotomy on this ntooth, placed MTA in the chamber, and restored it with amalgam.  It has been asymptomatic ever since.

 

 

What is an indirect pulp ncap?

 

 When a ndentist performs an indirect pulp cap on a tooth with a deep cavity, he does nnot expose the ‘nerve’ . Instead he leaves a small amount of ‘suspect’ tooth nstructure called affected dentin in between the nerve and the cavity npreparation. He usually places a medication over the affected dental such as ncalcium hydroxide that dries out the dentin and stimulates the formation of nsound secondary dentin.

 

If in the process of cleaning out ‘decay’ the nnerve is exposed, it sustains and injury that it may not be able to recover nfrom. The thinking behind this procedure is that by not exposing the pulp ndirectly, a root canal may be avoided, and the tooth will be OK with a final nrestoration, assuming the tooth remains asymptomatic.

 

Some dentists advocate leaving a sedative filling nin the tooth as an interim restoration and after a long period of time taking nit out and completely removing any soft dentin that remains. It is my nobservation that the Calcium hydroxide has the effect of desiccating the naffected dentin and I do not usually have to go back to remove the affected ndentin does not actually need to be removed at a later time.

Stages of tooth’ cavity disclosure:

1.      Unroofing of pulp chamber;

2.      gaining straight-line access to root canal norifices;

3.      final forming of ncarious cavity and tooth’ cavity.

Access should be ndesigned to reduce the curvature required to negotiate the apical 1/3 of the ncanal and will involve removal of the entire roof of the pulp chamber, nincluding the pulp horns. The access to cavity in anterior teeth should be nmidway between incisal edge and the cingulum, and iposterior teeth will vary according to the anatomy of the pulp chamber (Fig.1). nLining up a bur with the pre-operative radiograph will help to gauge the depth nof preparation. The turbine handpiece should be used to gain initial access, nreverting to slow speed for removal of the roof of the pulp chamber and nsubsequent preparation. When access is completed, the cavity should have a nsmooth funnel shape.

Tooth’ ncavity disclosure of posterior teeth is better to do in the projections of pulp nhorns, with the round-shaped burs. A shaping of tooth’ cavity walls, with the nhelp of fissure burs are performed.

Goals of endodontic access

Acces preparation is the most important phase of the technical aspects of nroot canal treatment. The bulk of procedural errors and treatment difficulties nare related to errors or problems in obtaining adequate access (Fig. n2).

 

The ideals of endodontic access are nas follows:

1.     nComplete removal of nthe chamber roof

2.     nRemoval of coronal npulp

3.     nStraight-line access nto facilitate placement of endodontic instruments.

Unroofing of the Pulp Chamber

Unroofing the nchamber and removing the coronal pulp facilitates the clinician’s ability to nvisualize the chamber floor and aids in locating the canals. Complete removal nof tissue and debris prevents subsequent infection. Unroofing the chamber and nremoving the coronal pulp (in vital cases) allow the clinician to see the npulpal floor. In cases of observable canals, most or all of the canal orifices nmay be easily located before the chamber is completely unroofed, but the nclinician may however miss canals.

Facilitation of Instrument Placement

Although ncontemporary endodontic techniques require fewer instruments, the overall nthrust of endodontic cleaning and shaping continues to be the serial placement ninto the root canal system of variably sized, tapered, or shaped instruments. nThis serial placement of instruments is greatly facilitated by spending a few nextra minutes on the access preparation.

  Commoterms and expressions used for endodontic disease conditions and treatment nprocedures

 

Pulpitis  Inflammation of the dental npulp. Symptomatic and asymptomatic pulpitis, as well as irreversible and nreversible pulpitis, are commonly used terms to specify lesions with and nwithout painful symptoms. The terms total and partial pulpitis are also in use.

Pulp nnecrosis.  Pulp ndeath. Pulp chamber is without of a functional pulp tissue. nNecrosis can be more or less complete, i.e. partial or total.

Apical nperiodontitis.  nAn inflammatory reaction of the tissues surrounding nthe root apex of a tooth. Symptomatic/asymptomatic apical periodontitis nand acute/chronic apical periodontitis, respectively, are applied to indicate nlesions with and without overt clinical symptoms such as pain, swelling and ntenderness. Dental or apical granuloma is a histological term for aestablished lesion. Apical, periapical and periradicular nare interchangeable terms to state the location of the process at or near the nroot tip.

Pulp capping n(lining placing)   Treatment procedure naimed at preserving a dental pulp that has been exposed to the oral nenvironment.

Partial pulpotomy   Treatment procedure by which the most (ofteinflamed) superficial portion (1–2 mm) of the coronal pulp is surgically nremoved with the aim of preserving the remaining tissue.

Pulpotomy (amputation)   Treatment procedure by which the coronal npulp tissue is surgically removed with the aim of preserving the remaining ntissue. The term pulpotomy is also used to describe a pain-relieving procedure nin an emergency treatment of symptomatic pulpitis.

Pulpectomy (extirpation)   Treatment procedure by which entire pulp ntissue (often inflamed) is surgically removed and replaced with a root filling.

(RCT)  nRoot canal treatment   Treatment of teeth nwith necrotic pulps where root canals are often infected.

Non-surgical retreatment    Treatment of root filled teeth with nclinical and/or radiographic signs of root canal infection, where root fillings nare removed, canals disinfected and refilled. May also be ncarried out to improve the technical quality of previous root fillings.

Surgical retreatment   Treatment procedure by which the root apex nof a tooth is surgically accessed to manage a root canal infection that has not nbeen successfully treated by RCT. Retrograde endodontics or surgical nendodontics are other terms for this procedure.

Apexification – treatment procedure by which closure of root apex is promoted by ncalcium hydroxide, in teeth where loss of vitality has occurred before normal ngrowth and development of the tooth was completed.

Apexogenesis – treatment nprocedure by which the preservation of the radicular pulp tissue allows ncontinuing development and apical maturation of teeth with open apices.

Traditional ndiscussions of canal preparation have recognized cleaning and shaping as ntwo distinct processes. Cleaning –refer nto the debridement of the root canal space and shaping as the step to prepare the canal for obturation. All nclinically accepted endodontic instruments and instrumentation techniques nattempt to perform both processes simultaneously.

Debridement nof the root canal space includes removal of vital and necrotic tissue, nbacteria, bacterial byproducts, and dentinal debris created during the cleaning nand shaping process. Irrigation and disinfection are integral parts of ndebridement.

Manipulations nof root canal treatment (RCT) are carried out manually or with the help of nrotary instruments by several treatment methods, the most widespread  among them are:

• apical-crown – nenvisage treatment from the apical hole to canal orifices with gradually nincreasing of  instrument diameter( e.g. nfrom №10 -№ 40)

• crown-apical n– envisage root canal treatment that nstarts from canal orifices to apical hole with a gradual decrease in instrument ndiameter(e.g. from №40 –№ 10)

• hybrid method nof treatment – have been developed out of the two methods. Starting coronally nwith larger instruments, often power driven, one works down the straight nportion of the canal with progressively smaller instruments, that is the ncrown-down approach. Then at this point, the procedure is reversed, starting at nthe apex with small instruments, and gradually, increasing in size as one works nback up the canal, that is the ‘step-back’ approach. This hybrid approach could nbe called the crown-down – step-back technique or ‘modified double-flared ntechnique’.

 

 

Step-back ntechnique. (Fig. n3, 4)An apical part of the root canal is prepared first and the canal nis then widened from apex to crown. Blockage of canals may occur using this ntechnique, and irrigation can be difficult. After determining the WL, the first nactive instrument to be inserted should be fine (№ 08, 10 or 15) 0,02 tapered, stainless steel file, curved and coated with nlubricant. The most important part of the Step-back preparation is the reuse of nfiles; one size smaller than the last one (recapitulation) used to prevent ndentine shavings from building up and causing blockage of the canal. Irrigatioalone may not be efficient in these cases for preventing clogging. Once the napical preparation is complete № 2 or 3 Gates Glidden are used to further nfunnel the preparation coronally.

 

 

Crown-down technique. (Fig. 5) At first n(along with several others) prepares the coronal part of the canal before the napical part. This has advantages and is the preferred technique. Initially nH-file № 15, 20 is penetrated root canal; then Gates Glidden drills (№2, 3), nflaring the coronal segment of root canal is used; determination of the WL and ncreation of an apical stop; then shaping the remaining canal in crown-dowapproach, using decreasing size of instruments in sequence.

 

Anticurvature filing.  It was developed to minimize nthe possibility of creating a ‘strip’ perforation on the inner walls of curved nroot canals. It is used in conjunction with other techniques or preparation, nand the essential principle is the direction of most force away from the ncurvature. The walls on the opposite side from the curve are instrumented more nthan the inner walls resulting in a decrease of the overall degree of canal ncurvature. Bottom Line: Anti-curvature approach can preserve dentinal thickness nnear furcation. It also gives a more straight line access deeper into the ncanal.

Balanced nforce technique. (Fig. 6) It’s ninvolves using blunt-tipped files with an anticlockwise rotation whilst napplying an apically directed force. It requires practise to master but is nparticularly useful when preparing the apical part of severely curved canals.

 

Advantages of orifice enlargement (Fig. 7)

Effectively, ⇓ nthe curvature in the coronal part of the root canal, allowing straighter access nfor files to the apical region. It therefore reduces the possibility of apical ntransportation (zipping). 

It allows improved access for the flow of nirrigant solution within the canal. 

It reduces the probability of apical extrusion of ninfected material as most of the canal debris is removed before apical ninstrumentation takes place. This is particularly important because the nmajority of bacteria of an infected root canal are located in the coronal nregion.

 

Passing and enlargement of root canal (especially nnarrow and sclerosed) is not always possible to implement using only endodontic ninstruments. In such cases, additional chemical expansion is conducted. Such ntechnique involves the use of different types of acids for decalcification of ndentin.

 

In root canal ntreatment is often used products based on EDTA.

 For chemical enlargement of a nroot canal a small amount of gel product is applied to endodontic instruments nand instrumental treatment of root canal is performed. The procedure is nrepeated several times. After obtaining the required result, canal is washed nwith solution of sodium hypochlorite or distilled water.

Drugs for chemical nenlargement of root canals

 

Root canal treatment should include thorough instrumental ndebridement and medicament treatment as well (antiseptic solutions), these two procedures should go together.

Irrigants. These nare required to flush out debris and lubricate instruments. Dilute sodium nhypochlorite is generally considered to be the best irrigant as it is nbactericidal and dissolves organic debris. The normal concentration is 2.5% navailable chlorine. Chelating agents which softedentine by their demineralizing action are particularly helpful when trying to nnegotiate sclerosed or blocked canals. It is recommended to coat instrument iantiseptic solution every time it is inserted into root canal, because nirrigants not only cleans the root canal, but also dissolves flakes of debris non the working part of instrument.

Solutions that can be used as nirrigants in medicament treatment of root canals: 3% sodium hypochlorite sol., n0,2% chlorhexidini, 1% sol. Chloramine, 2-5% Iodide nsol., 3% H₂O₂ , Dikamfen, Formokrezol (used for antiseptic treatment of root canals nin the case of apical periodontitis)

Delivery of Irrigants

Syringe

Commercial nendodontic syringes have a fine bore to allow delivery of irrigant into the napical part of the root canal system. Gauge 27 needles are manufactured with a cut away tip to allow irrigant to pass out sideways and reduce the risk of napical extrusion.

Intracanal medicaments are advocated nto:

• nEliminate bacteria after chemomechanical ninstrumentation

• nReduce inflammation of the periapical tissues

• nDissolve remaining organic material

• nCounteract coronal microleakage.

 

Prepared nroot canal for sealing, regardless of the method of instrumental treatment, must nfulfill the following criteria as follows:

– nTo be sufficiently enlarged;

– nTo have a conical shape;

– nTo have formed an apical stop;

– nDo not contain a necrotic dentin;

– nDo not have typical smell (when it was apical periodontitis);

– nTo be cleaned and dried;

– nDo not have a painful reaction to percussion (when it was apical nperiodontitis).

 

Common errors in canal preparation

Incomplete debridement: nshort working length, missed canals. 

 Lateral nperforation: often occurs as a result of poor access.  

Apical perforation: nmakes filling difficult.

Ledge formation: ncan be very difficult to bypass.

Apical transportation n(zipping) (Fig. 8) A file will tend to straighten out when used in a ncurved canal and straightening can transport the apical part of the preparatioaway from the curvature. The use of flexible files reduces the likelihood of nthis happening. 

Elbow formation When apical zipping happens, a narrowing often occurs ncoronal to this in the canal such that the canal is hourglass in shape. This narrowing nis termed an elbow. 

Strip nperforation A perforation occurring nin the inner or furcal wall of a curved root canal, nusually towards the coronal end.

 

 

SOME ENDODONTIC PROBLEMS AND THEIR nMANAGEMENT

Fractured ninstruments. Sometimes it is possible to get hold nof the fractured portion with a pair of fine mosquitos. If not, insertion of a nfine file beside the instrument may dislodge it. Should the fractured piece be nlodged in the apical portion of the canal it may be better to fill the canal nbelow it and keep it under observation, resorting to an apicectomy as a nlast-ditch solution.

Fractured ninstrument removal. Ultrasonic nvibration may be used to facilitate fractured instrument removal. The cliniciamust take care to ascertain the type of metalic obstructiobecause nickel-titanium (NiTi) and stainless steel nrespond differently to ultrasonic vibration. Direct ultrasonic vibration causes nNiTi to fragment, so the clinician must work ncarefully around the fragment. Stainless steel is more resistant to vibratioand responds to it by subsequently loosening.

Ultrasonic vibration is applied directly to nstainless steel files. Fine inserts can be used to work counter-clockwise naround broken instruments. This technique often results in an “unscrewing” naction that assists in removal.

Recurrent symptoms/intractable ninfection If thorough ncleaning and repeated dressing of the canal with calcium hydroxide are nunsuccessful, it may be necessary to do an apicectomy. Do not routinely turn to nsurgery for failed cases consider retreatment in the first instance.

If careful exploration with a small nfile is unsuccessful, investigation of the expected nposition of the canal entrance with a small round bur may help. Once the canal nis found, a No. 8 or 10 file should be used to try and negotiate it, using nEDTA, File Eze, or RC Prep as a lubricant, and the ncanal prepared and filled conventionally. Success rates of 80% have beereported for canals that were hairline or undetectable on radiographs. nOccasionally, a total blockage of the canal is encountered, in which case the nfilling is placed to this level and/or an apicectomy done.

Pulp stones nin the pulp chamber can usually be flicked out. If they occur in the canal use nEDTA and a small file to try and dislodge them.

Paifollowing instrumentation. This nis usually due to instruments or irrigants, or to debris being forced into the napical tissues. Placement of a small amount of Ledermix(Antibiotic/steroid npaste ) in the canal may provide symptomatic relief, but care is required not nto breach the apex. Occasionally, an acute flare-up of a previously nasymptomatic tooth occurs following initial instrumentation this is called a nphoenix abscess. Loss of face is saved by warning patients that this cahappen. Affected teeth should be opened and irrigated and if possible resealed. nThis may need to be repeated after 24-48 h.

Perforations can be iatrogenic or ncaused by resorption

In the latter case, dressing with non-setting ncalcium hydroxide may help to arrest the resorption and promote formation of a ncalcific barrier. Increasingly MTA is being used for the repair of perforations nand in surgical endodontics as a retrograde filling material with excellent nresults. Management of traumatic perforations depends upon their size and nposition:

Pulp chamber floor If small perfortion, none can cover with calcium hydroxide and fill with GP or GI, but if large, hemisection or extraction may be necessary.

Lateral perforation If this occurs near the ngingival margin it can be incorporated in the final restoration of the crown, ne.g. a diaphragm post and core crown. If in the middle 1/3, the remainder of nthe canal may be cleaned by passing instruments down the side of the wall nopposite the perforation. Then the canal can be filled with GP, using a lateral ncondensation technique to try and occlude the perforation as well. Larger nperforations may require a surgical approach and in multirooted nteeth hemisection or extraction may be unavoidable. n 

Apical 1/3 It is usually worth trying a vertical condensation technique nto attempt to fill both the perforation and the remainder of the canal. If this nis unsuccessful an apicectomy will be required.

Ledge formation If this occurs, return to na small file curved at the apex to the working length and use this to try and nfile away the ledge, using EDTA or RC- Prep as lubricants.