In parts 1 and 2 of this 3-part articleseries we discussed some of the waysendodontics melds with restorative den-

tistry. We also discussed the rationalebehind, and the design features of, theEndoSequence (Brasseler USA) file. Addi-tionally, we reviewed instrumentation tech-niques from both the basic and advancedperspectives. Progressing along this Endo-Restorative Continuum, we wish to nowaddress obturation of the root canal spaceand introduce a new post concept.

OBTURATIONIt is a continuing goal of Real World Endo todevelop products and techniques that willdeliver excellent endodontic results with op-timal efficiency. An additional goal includesdesigning these techniques in such a waythat the majority of practitioners will beable to predictably and successfully performthese procedures. The basic EndoSequencefile system gives all clinicians the ability tomachine predictable shapes that ultimatelylead to synchronicity between the prepara-tion and the master cone fit (Figure 1).Embracing this concept and taking it to

advanced levels in obturation, are sealer-based obturation systems based on glassionomer (GI) and bioceramic technologies.

Glass Ionomer Obturation TechnologiesActiv GP (Brasseler USA) is a system whichutilizes improved GI technology—both as asealer and as a special GI coated gutta-per-cha cone—to create a true single conemonobloc obturation (Figure 2). This is verysignificant because, for the first time, a truemonobloc will allow us to create a hermeticseal within the root canal space. A hermeticseal has been a goal of endodontics for morethan 50 years. Furthermore, a true singlecone technique is a method that is now clin-ically achievable as a result of improvedmaterial science. More importantly, such atechnique (when performed properly) willgive the greatest percentage of cliniciansthe ability to produce superior obturationresults.1

In the original pursuit of this goal, GI(Ketac-Endo) was selected because of itssuperior biocompatibility and its physicalproperties. However, a problem historicallywith the early generations of GI and resinsealers was that neither method was able todevelop a true monobloc. Although therewere advocates on both sides of the argu-ment, research has shown that both the GIand resins sealers have had some advan-tages and some limitations. However, therewas one thing that both the resin and GIadvocates could agree on—that obturationwas headed in the direction of sealer basedtechniques rather than the mechanicalpacking and melting of gutta-percha. Thismade sense from both the technical and sci-ence sides.

It is also very interesting to see how the2 materials differed. The resins were shownto have a good seal between the sealer andthe gutta-percha cone, but their seal to thecanal wall was questionable. On the otherhand, GI cements displayed an excellentseal to the canal wall, but their seal to thegutta-percha was less than ideal. So as the20th Century came to a close, we still foundourselves searching for a technique thatcould consistently deliver a true monoblocobturation.1

Activ GP obturation is a single cone

technique that requires a minimal amountof sealer rather than the excess that is uti-lized in other methods. This is because itinvolves a precision-based system. As previ-ously mentioned, precision-based endodon-tics requires accuracy between the file andthe master cone. Similar to the regularEndoSequence gutta-percha, all Activ GPpoints are laser-verified to precisely matchthe preparations made by the .04 or .06tapered Endo-Sequence file system (Figure3). The precision matching of the primarycone to the preparation (endodontic syn-chronicity) is very important with any sin-gle cone technique. This is because the accu-racy of the cone fit to the preparation mini-

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... an endodontic system(EndoSequence) has been intro-duced that bridges the gapbetween root canal therapy andrestorative dentistry.

EndoSequence:Melding EndodonticsWithRestorative Dentistry,Part 3

This is Part 3 of a 3-part article series. Part 2 ofDrs. Koch and Brave’s article was published inthe February 2009 issue of Dentistry Today andcan be found in our archived articles at den-tistrytoday.com. This, and all future articles thatare presented in multiple parts, will now beavailable to our readers for review in theirentirety at our Web site dentistrytoday.com. Thisis being done to help those readers who may havemissed a portion of any multiple-part article, andwill also facilitate the ability to review a com-plete article in its entirety for others.

Kenneth A.Koch, DMD

Dennis Brave,DDS

Figure 1b. Final obturator with burnout for post.

Figure 1a. Mandibular premolar demonstrating the pre-cise synchronicity established between the lastEndoSequence rotary file and master cone.

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mizes the amount of sealer and anydimensional change. Althoughdimensional change can occur withall sealers, GI is very stable and doesnot shrink.

Furthermore, due to the pre-dictability of shape associated withconstant tapers, it may be statedthat a true single cone techniqueshould be accomplished with a con-stant tapered preparation such as a.04 or .06. A variable taper techniqueis not recommended because its lackof shaping predictability (and its cor-responding lack of reproducibility)will lead to a less than ideal cone fit.This lack of endodontic synchronici-ty is why all variable taper prepara-tions are associated with thermo-plastic techniques.

Bioceramic Obturation TechnologyWhile GI has been a huge help inestablishing a true single cone fillingtechnique, the obturation equation

has further changed with the intro-duction of a new material(EndoSequence BC Sealer [BrasselerUSA]), which utilizes bioceramictechnology. However, before we dis-cuss how this specific sealer ischanging obturation, we need toaddress some of the merits associat-ed with bioceramics.

The first question we need to askourselves is, “What are bioceram-ics?” Bioceramics are ceramic mate-rials specifically designed for use inmedicine and dentistry. They includealumina and zirconia, bioactiveglass, glass ceramics, coatings andcomposites, hydroxyapatite andresorbable calcium phosphates, andradiotherapy glasses.2-4 Bioceram-ics are widely used for orthopedicapplications, such as joint or tissuereplacements, as a coating to im-prove the biocompatibily of metalimplants, and they can also act asresorbable lattices providing aframework that is eventually dis-solved as the body rebuilds tissue.

The properties associated withbioceramics make them very attrac-tive to both medicine and dentistry.In addition to being nontoxic, bioce-ramics can be classified as:2-5• Bioinert: noninteractive with bio-

logical systems.• Bioactive: durable tissues that can

undergo interfacial interactionswith surrounding tissue.There are numerous bioceramics

currently in use in both dentistry andmedicine, although more are used inmedicine. Alumina and zirconia areamong the bioinert ceramics used forprosthetic devices. Bioactive glassesand glass ceramics are available foruse in dentistry under various tradenames. In addition, porous ceramicssuch as calcium phosphate basedmaterials have been used for fillingbone defects. Also, some calcium sili-cates (MTA [DENTSPLY TulsaDental Specialties] and BioAggregate[DiaDent]) have been used in den-tistry as root repair materials and forapical retrofills.

However, we must ask ourselvesagain, “What are the advantages ofbioceramics in dental applications?”Clearly the first answer is related tophysical properties. Bioceramics areexceedingly biocompatible, nontoxic,do not shrink, and are chemicallystable within the biological environ-ment. Secondly, and very importantin endodontics, bioceramics will notresult in a significant inflammatoryresponse if an overfill occurs duringthe obturation process or in a rootrepair. A further advantage of thematerial itself is its ability to formhydroxyapatite and a bond betweendentin and filling materials.

While the properties associated

with bioceramics make them veryattractive to dentistry, in general,what would be their advantage ifused as an endodontic sealer? Fromour perspective as clinicians, some ofthe advantages are: enhanced bio-compatibility, possible increasedstrength of the root following obtu-ration, high pH (12.9) during thesetting process which is stronglyantibacterial, sealing ability, andease of use.6

The introduction of Endo-Sequence BC Sealer (Figure 4) al-lows us, for the first time, to takeadvantage of all the benefits associ-ated with bioceramics; but to notlimit its use to merely root repairsand apical retrofills. This is possiblebecause of nanotechnology—the par-ticle size of BC Sealer is so fine thatit can actually be used with a capil-lary tip. This material has beendesigned as a nontoxic hydraulic cal-cium silicate cement that is easy touse as an endodontic sealer. The pur-pose of BC Sealer is to im-prove theconvenience and delivery method ofan excellent root canal sealer, whilesimultaneously utilizing the waterinherent in the dentinal tubules todrive the hydration reaction of thematerial, thereby shortening the set-ting time. Dentin is composed ofapproximately 20% (by volume)water7, and it is this water whichinitiates the setting of the materialand ultimately results in the forma-tion of hydroxyapatite.

For clinical purposes, the advan-tages of a premixed endodontic ce-ment (sealer) should be obvious. Inaddition to a significant saving of timeand convenience, one of the majorissues associated with the mixing ofany cement, or sealer, is an insuffi-cient and nonhomogenous mix, whichultimately may compromise the bene-fits associated with the material.Keeping this in mind, BC Sealer hasbeen designed as a premixed bioce-ramic sealer that hardens only whenexposed to a moist environment (pro-duced by dentinal tubules).

The technique with this materialis straightforward. Simply removethe syringe cap from the Endo-Sequence BC Sealer syringe andattach an Intra Canal Tip of yourchoice to the hub of the syringe. TheIntra Canal Tip is flexible and canbe bent to facilitate access to the rootcanal (Figure 5). Then, insert the tipof the syringe into the canal no deep-er than the coronal one third. Gentlyand smoothly dispense a smallamount (1 to 2 calibration markings)of EndoSequence BC Sealer into theroot canal by compressing theplunger of the syringe. Using a No.15 hand file or something compara-ble, lightly coat the canal walls with

the existing sealer in the canal.Next, coat the master gutta-perchacone with a thin layer of sealer andthen very slowly insert it into thecanal. The synchronized mastergutta-percha cone will carry suffi-cient material to seal the apex.

The precise fit of the Endo-Sequence gutta-percha master cone(in combination with a constanttaper preparation) creates excellenthydraulics and, for that reason, it isrecommended that the practitioneruse only a small amount of sealer.Furthermore, as with all obturation

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Figure 2. Light refractive metallograph show-ing the relationship between the dentin, ActivGP Sealer (Brasseler USA), and the mastercone. Note: this image demonstrates amonobloc obturation.

Figure 3. Activ GP (Brasseler USA) is availablein a nonspill gutta-percha organizer.

Figure 4. EndoSequence BC Sealer (BrasselerUSA) is a new bioceramic sealer.

Figure 7. Post-op radiograph of maxillarymolar with .04 tapers and BC Sealer. As evi-dence of the flow ability of this sealer, pleasenote the sealed delta in the palatal root.Courtesy of Dr. Alex Fleury, Dallas.

Figure 5. The intra canal tip can be precurvedto expedite placement of the sealer.

Figure 6. Post–op radiograph of a mandibularmolar case with .04 tapers and BC Sealer.Notice the endodontic synchronicity of thepreparation and obturation particularly in themesial canals. Courtesy of Dr. Alex Fleury,Dallas.

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techniques, it is important to insertthe master cone slowly to its finalworking length. Finally, here’s moregood news. The glass components inthe bioceramic sealer bond to theActiv GP GI coated cones.

IMPORTANCE OF A TRUE SINGLECONE TECHNIQUE

When we talk about a true singlecone technique let’s think aboutwhat this really means. The easiestway to comprehend this is to com-pare it to carrier-based techniques.In these techniques, you heat theobturator and then insert it into thetooth, delivering it to a point just shyof the working length. Basically, you

are using a hard plastic carrier todeliver heated gutta-percha (orresin) into the root canal system.The primary limitation associatedwith this technique is the concern ofstripping (denuding) the carrier ofgutta-percha (or resin) when it isinserted into the canal orifice.Additionally, there is a lack of apicalcontrol that is the result of usingheated gutta-percha (or resin).However, the concept of filling a rootcanal with a device that you can“feel” is admirable. It is essentiallythe same with an Activ GP cone andBC Sealer, but with a few differ-ences. Again think about what youare actually doing. In essence, youare using a stiff carrier (one that isactually a stiffer gutta-percha cone)to deliver a dimensionally stable bio-ceramic sealer into the root canalsystem. So, while you get the “feel” ofa carrier-based technique, you havethe advantage of using gutta-perchaas a carrier to deliver sealer. Afterall, it is the sealer that creates theseal in obturation, not heated gutta-percha. Additionally, post prepara-tion will be a lot easier because youare now removing gutta-percha, notcutting plastic.

The 5 cases seen in figures 6 to 9evidence the results of Activ GPcones used with BC Sealer.

RETREATMENTRetreatment also remains an impor-tant aspect of advanced endodontictherapy. It is an area where an effi-cient instrument excels. Dr. WaynePulver (oral communication, March2008), an endodontist in Ontario,Canada, describes retreatment withEndoSequence in the following man-ner. “Retreatment of plastic fillingmaterials such as gutta-percha canbe readily accomplished using theEndoSequence instruments. Thebulk of the filling material can beremoved with the use of a heatedinstrument, such as the ‘Touch’nHeat’ by SybronEndo, or the use ofGates Glidden drills in a crowndown technique: No. 4, No. 3, No. 2.Avoid the use of large GatesGliddens such as Nos. 5 and 6 exceptin very large canals because theseinstruments may over enlarge thecoronal part of the canal. The use ofsolvents can expedite the process.However, judicial use is suggestedbecause excess solvent can causeperiapical inflammation and poten-tial postoperative discomfort. Ifused, the solvent should be placedusing a tuberculine syringe to con-trol how much is placed into thechamber of the tooth.”

Dr. Pulver goes on to say, “Oncethe bulk of the material is removed,the EndoSequence files can now beintroduced into the tooth. Depending

on the size of the canal, .06 taperswork best except in very fine canals.The EndoSequence file design isideal for gutta-percha removal. Theinstrument is a true reamer with anoncutting tip. The instrumentshould be used in a crown downtechnique. In most canals, the No. 30.06 is the first instrument to be used.Using a torque control motor at 500rpm, the file is taken to resistanceand withdrawn slightly and then itis reinserted 3 times, advancing itapproximately 1 mm each time.Proceed apically using the sametechnique with the No. 25 and No. 20.06 files. Once the instrumentationis within 5 mm of the apex, considerthe final removal of the plastic mate-rial with hand files and solvent. Thiswill create a glide path which willallow for final instrumentationusing the No. 30, No. 25, and No. 20Sequence files.”

Dr. Pulver has given some excel-lent clinical tips how to facilitate theretreatment of gutta-percha. Noticethat he takes the first file in retreat-ment to resistance, rather thanengagement. Thereafter, he takeseach file to engagement which isabout 1 mm each time.

Dr. Ali Nasseh, an endodontist inBoston, has also addressed the ques-tion of retreating bioceramic sealercases. Historically, there had beenconfusion about retreating GIendodontic cases (GI sealer is defi-nitely retreatable when used as asealer8) and similarly, there has alsobeen confusion concerning theretreatability of bioceramics. Thekey is using bioceramics as a sealer,not a filler. This is why endodonticsynchronicity is so important. Andagain, this is also why the use of con-stant tapers makes so much senseby minimizing the amount ofendodontic sealer thereby facilitat-ing retreatment.

The technique is relativelystraightforward, as Dr. Nasseh (oralcommunication, December 2008)describes it:

“The key in retreating bioceramiccases is to use an ultrasonic with acopious amount of water. This is par-ticularly important at the start of theprocedure in the coronal third of thetooth.Work the ultrasonic (with lots ofwater) down the canal to approximate-ly half its length. At this point, add asolvent to the canal (chloroform) andswitch over to an EndoSequence file(No. 30 or 35/.04 taper) run at anincreased rate of speed (1,000 rpm).Proceedwith this file, all theway to theworking length, using solvent whenindicated.An alternative is to use handfiles for the final 2 to 3 mm and thenfollow the gutta-percha removal with arotary file to ensure synchronicity.”

The case seen in Figure 10

demonstrates the retreatment of BCSealer.

A final aspect of the Endo-Restorative Continuum, and the onewhich ultimately melds restorativedentistry with endodontics, is therestoration of the endodontically treat-ed tooth. It is well known and estab-lished that the ferrule effect (a mini-mum of 1.5 to 2.0 mm of vertical toothstructure at the gingival aspect of acrown preparation) is a key factor inthe long-term success of these teeth.9But let’s examine something morebasic regarding posts.

POSTSIt has been commonly accepted thatall posts weaken teeth, and it is gen-erally recognized that the main pur-pose of a post is to retain the core.Yet, post design as it relates toendodontic shaping, has become aconfusing issue. Years ago there wasa mantra in restorative dentistry,“tapered posts split roots.” That wasbecause all the specialists at the timewere creating essentially parallelpreparations with .02 taper handfiles and if one inserted a taperedpost into such a shape, you incurredthe risk of splitting the tooth.Consequently, we used parallel posts.Then endodontic shaping evolved tothe use of tapered preparations.

Today, while most practitionersare creating tapered endodonticpreparations (constant or variable)many clinicians still are attemptingto place parallel posts into theseshapes. This likewise makes littlesense and, as a result, clinicians areexcessively enlarging their parallelpost preps to gain some “bite” on thesides of the tapered canal walls. Un-fortunately, the more coronal radicu-lar dentin that has been removed,the less retentive is the final restora-tion. Additionally, this can alsoseverely compromise the tooth and,as a result, we are witnessing manyfractures emanating from the bot-tom of the posts (Figure 11). The netresult is a diminished long-termprognosis. The answer to this dilem-ma is straightforward. Use a postdesign that matches the shape of theendodontic preparation. When onethinks about it, this is what castposts were attempting to create—posts that precisely match the shapeof the endodontic preparation!

A solution to this discrepancybetween post size and canal shapehas been achieved with the introduc-tion of the EndoSequence PostSystem (Brasseler USA). TheEndoSequence rotary file creates afully tapered preparation (.04 or .06)from orifice to apex. The correspon-ding paper points and gutta-perchacones are laser verified to preciselymatch the shape created in the

Figure 8. Pre- and post-op radiographs of amandibular molar with .04 taper preparationsand BC Sealer. Courtesy of Dr. Ali Nasseh,Boston.

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Figure 9. Pre- and post-op radiographs of amaxillary molar with .04 tapers and BC Sealer.Courtesy of Dr. Ali Nasseh, Boston.

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canal. The EndoSequence post goesone step further and is likewisetapered (.04 or .06) to match theexact shape of the instrumentedcanal. Because of the synchronicitythat has been established, there isno need to alter the shape of the rootcanal preparation to match the post(Figure 12). In a sense, the lastrotary file taken to length is actingas a post drill.

This concept has also beenaddressed in a recent article by Dr.Richard Trushkowsky10 when hewrote, “The ideal post should havethe same shape as the endodonticpreparation, and should be noncor-rosive, readily adjusted, and able tobe removed without difficulty.”Furthermore, since the dual cureresin cement that is used to bond thepost to the canal wall is also thesame material used to create thebuildup (EndoSequence Build-up),

one can think of this technique as anintraradicular core buildup with arebar. Not only is this “post tech-nique” easy to replicate, it is kinderand much safer.

CONCLUSIONIn this 3-part article series, a casehas been made for the importance ofmaintaining endodontics as part ofthe treatment planning process andfor performing endodontics in amore conservative fashion. Whentalking about doing “conservativeendo,” everyone thinks of coronaltooth structure, but it is the preser-vation of the radicular dentin (par-ticularly in the coronal third of theroot) that will enhance the long-termretention of the endodonticallytreated tooth.

Additionally, it has been empha-sized in this article that we need tothink in terms of an Endo-Restorative Continuum rather thanjust endodontics. Furthermore, anendodontic system (EndoSequence)has been introduced that bridges thegap between root canal therapy andrestorative dentistry. This is signifi-cant because this “melding” ofendodontics with restorative den-tistry now gives you the ability tooffer your patients endodontic thera-py that will stand the test of time.�

References1. Koch K, Brave D. A new endodontic obturation

technique. Dent Today. May 2006;25:102-107.2. Best SM, Porter AE, Thian ES, et al.

Bioceramics: past, present and for the future. JEur Ceramic Soc. 2008;28:1319-1327.

3. Dubok VA. Bioceramics: yesterday, today, tomor-row. Powder Metallurgy and Metal Ceramics.2000;39:381-394.

4. Hench LL. Bioceramics: from concept to clinic. JAm Ceram Soc. 1991;74:1487-1510.

5. Hickman K. Bioceramics. CSA Web site.http://www.csa.com/discoveryguides/archives/bceramics.php. Released April 1999; AccessedJanuary 15, 2009.

6. Koch K, Brave D. A new day has dawned: theincreased use of bioceramics in endodontics.

Dentaltown. In press.7. Pashley DH. Dynamics of the pulpo-dentin com-

plex. Crit Rev Oral Biol Med. 1996;7:104-133.8. Friedman S, Moshonov J, Trope M. Residue of

gutta-percha and a glass ionomer cement seal-er following root canal retreatment. Int Endod J.1993;26:169-172.

9. Schwartz RS, Robbins JW. Post placement andrestoration of endodontically treated teeth: a lit-erature review. J Endod. 2004;30:289-301.

10. Trushkowsky R. Fiber post selection and place-ment criteria: a review. Inside Dentistry.2008;4:86-94.

Dr. Koch is the Founder and past director ofthe New Program in postdoctoral endodonticsat the Harvard School of Dental Medicine. Inaddition to having maintained a private prac-tice limited to endodontics, he has writtennumerous articles on endodontics and lectur-ers worldwide. He is a co-founder of RealWorld Endo and can be reached by visitingrealworldendo.com.

Dr. Brave is a Diplomate of the AmericanBoard of Endodontics and is a member of theCollege of Diplomates. In endodontic practicefor more than 25 years, he has lecturedextensively on endodontics and holds severalpatents, including the VisiFrame. Formerly anassociate clinical professor at the Universityof Pennsylvania, Dr. Brave currently holds astaff position at The Johns Hopkins Hospital.He is a co-founder of Real World Endo andcan be reached by visiting realworlden-do.com.

DISCLOSURE: Drs. Koch and Brave, inassociation with Brasseler USA, are thedevelopers of the EndoSequence system.

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Figure 11. Fracture emanating from the bot-tom of a post.

Figure 12. Complete endodontic synchronicity—from file through post placement (in blocks).Figure 10. Pre- and post-op radiographs of acase initially obturated with Activ GP and BCSealer and then retreated and obturated withthe same technique. Courtesy of Dr. AliNasseh, Boston.

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Other articles linked in this seriescan be found on

www.dentistrytoday.com

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