roots

rootsthe international magazine of endodontics

_working lengthEndodontic success and working length: thinking three-dimensionally

_clinicalNonsurgical therapy of mucosal and cutaneous fistulae

_trendsCeramics-based sealers as new alternative to currently used endodontic sealers

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i s sn 1616-6345 Vol. 5 • Issue 1/2009

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roots _ contents I

roots 1_2009

I trends

4 Endodontic success and working length: thinking three-dimensionally _ E. Steve Senia

I research

12 The leakage resistance of endodontic fiber obturator _ Gregori M. Kurtzman & J. A. von Fraunhofer

I trends

18 K3 rotary nickel titanium instrumentation: Blending safety and efficiency _ Gary Glassman

I trends

26 Answering two frequently asked clinical endodontic questions: How much taper? How do I troubleshoot my apex locator? _ Richard Mounce

I trends

32 Nonsurgical therapy of mucosal and cutaneous fistulae _ Arnaldo Castellucci

I research

42 Ceramics-based sealers as new alternative to currently used endodontic sealers _ Deyan Kossev & Valeri Stefanov

I about the publisher

49 _ submissions 50 _ imprint

To power source

Obturated canal

Detector wire(PVC-covered electrical wire)

Figure 1. Schematic diagram of test toothpage 12 page 18

page 32 page 42

I on the coverThe cover image for this issue of Roots magazine is courtesy of Dr. Eric Herbranson, 3D Interactive Tooth Atlas, Brown and Herbranson Imaging, eHuman.com.

page 6

page 26

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I trends_ working length

In the article “Endodontic success: it’s all about the apical third” (Roots magazine, Vol. 4, Issue 1, 2008, pages 14–19), we introduced the term working width (WW). Don’t be surprised if you have never heard this term — it’s quite

new and warrants a brief description. WW is the canal’s pre-instrumented diameter, adjacent and coronal to the apical constriction (Fig. 1). I like this term very much, because it is a valuable reminder that canals are three-dimensional. Instrumenta-tion should address a working length and a working width. My last article focused on working width, this article focuses on working length.

Definition of working length There is considerable disagreement regarding ex-

actly where working length (WL) should terminate. Let’s explore the reasons and try to make sense of it all. The American Association of Endodontists’ Glos-sary of Endodontic Terms states: “working length is the distance from a coronal reference point to the point at which canal preparation and obturation should terminate.”1 Where is the disagreement? The definition doesn’t tell us where WL should terminate. Exactly where should it be? Our forefathers hotly debated the question for many years, and the issue appeared to be resolved. Unfortunately, WL is once again embroiled in controversy.

Our forefathers concluded that instrumenta-tion should end at the cementodentinal junction (CDJ) (Fig. 1), which is approximately co-located with the apical constriction. Most agree with that

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Endodontic success andworking length: thinking three-dimensionallyAuthor_ E. Steve Senia, U.S.A.

Fig. 1_Root-end anatomy. Working Width (WW), outlined in blue, is

the canal width coronal to the constriction. If the average size of a constriction is #30, a larger instrument is required to clean

this area. Note that the CDJ (black arrows) is co-located with the

constriction.

Fig. 2a_Photograph showing the foramen, constriction and apex.

RO0109_1-52.indd 4 3/5/09 1:09:38 PM

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I 07roots 1_2009

trends_ working length I

location because the pulp makes dentin and the periodontium makes cementum. Instrumentation should remove pulp tissue and not invade the peri-odontium. That’s not to say that I’m against passing a patency file past the CDJ or even slightly beyond the foramen. However, remember the formula, Area = p (pi) times the radius squared. This means that a #15 (0.15 mm) patency file’s tip occupies only 5 percent of the average foramen’s cross-sectional area (0.60 mm) and only 25 percent of the average constric-tion’s area (0.30 mm)!2

I suspect patency files are used more for warning of an impending ledge than for maintaining patency. The downsides are the likelihood of a patency file lacerating vital tissue beyond the constriction and possibly causing postoperative pain in an asympto-matic vital case. A clean cut of the pulp at its narrow-est point (apical constriction) is a more biologically acceptable approach. In necrotic cases it would likely push infected material into the periapical tissue and possibly cause a “flare-up.”

Termination pointWhere to terminate WL (our clinical target) re-

quires two reference points. The first one is the coro-nal reference point on the crown, and the second is in the apical part of the canal. The AAE Glossary states that a root canal is: “a passage or channel in the root of a tooth extending from the pulp chamber to the apical foramen.”1 Note that the foramen defines the end of the canal. This narrows the choices for WL to somewhere between the foramen and the CDJ/constriction.

The Glossary positions the apical constriction

“usually 0.5 to 1.0 mm short of the center of the api-cal foramen,” but positions the CDJ “ranging from 0.5 to 3.0 mm from the anatomic apex.”1 The last word, apex, is very important. If the CDJ can be as much as 3 mm from the apex, it means that the apex is not a precise reference point for WL determination and should not be used. Clearly, apex and foramen can’t be used interchangeably, and evaluating the quality of an obturation by its distance from the apex is wrong.

A meaningful discussion of WL can only take place when it is understood to be measured in mil-limeters from the foramen and not the apex. So let’s not talk about the apex because it’s irrelevant, and let’s not pretend that the apex is the same as the foramen. It’s all about the foramen, which is usually not at the apex.2,3 Gutierrez and Aguayo3 examined 140 teeth with a scanning electron microscope. They found no foramina located exactly at the apex, and the average distance of the foramen from the apex ranged from 0.2 mm to 3.8 mm. The foramen gives a precise reference point for WL determination — the apex does not.

If we use the foramen, rather than CDJ/constric-tion or apex, as a firm reference point, we can really narrow down the best locations for WL. I purposely use the plural to emphasize the two acceptable loca-tions — 0.5 mm from the foramen or 1.0 mm from the foramen. Why not agree on a WL that ranges from 0.5 mm to 1.0 mm short of the foramen? I think that’s reasonable, and here’s why. Let’s say that I believe WL should be 0.5 mm short of the foramen, whereas you think it should be 1.0 mm short of it. Could I say that my choice is correct, whereas yours is not and your

Fig. 2b_A “perfect” obturation “closing the door” against further contamination from above; bacteria apical to the gutta-percha are trapped and destroyed.

Fig. 2c_WL short of the desired location (constriction), but the WW is correct and the door is closed.

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08 I roots1_2009

treatment will fail? Of course not!

The body’s defenses Let’s discuss WL further using a photograph of a

root end (Fig. 2a) and add an instrumented and obtu-rated canal (Fig. 2b), closing the door and preventing further bacterial contamination from above. Bacte-ria apical to the gutta-percha are cornered with no place to run. They are destroyed by polymorphonu-clear leukocytes (PMN), and any remaining debris is cleaned up by the macrophages.

Hypothetically, let’s now miss our WL by 1 mm (short) (Fig. 2c). Just as in Figure 2b, the door has been shut and the bacteria are trapped. What hap-pens to the bacteria between the foramen and the gutta-percha seal when the WL is perfect or 1 mm short of that length? Same answer, the bacteria are attacked and destroyed by the PMN — the major cir-culating cell in the immune system, whose function is to kill bacteria. (In fact, when the body encounters infection, the production of PMN increases tenfold.) Another body defense cell is the macrophage, whose function is to clean up the debris4 — a task it does very well — as evidenced by the rapid disappearance of extruded root canal sealer.

Now let’s change the situation to where WL is per-fect, but WW is not (Fig. 2d). There is a dramatic dif-ference between what happens to the bacteria in a correctly cleaned and filled canal (Fig. 2e) versus one where necrotic tissue remains. When this happens, the door is not shut since the root canal sealer can-not replace the infected tissue. Bacteria feast on the tissue and reproduce rapidly. Because the infected pulp is 1 mm from the apex (Fig. 2d), the continuous production of bacteria and their toxins exiting the foramen was too much for the body defenses and the case failed.

There seems to be a widespread belief that the immune system behaves differently at the apex compared to other places in the body. The apex is not a mystery zone — the defense mechanisms there are “alive and well” and fully functional. The mis-understanding, I think, arises from the errant belief that canals in necrotic cases lack a blood supply. This is true — high up in the canal — but not within the

region associated with WL. This part of the canal is in close proximity to a generous blood supply.

How to locate WL clinicallyNow that we have decided that WL should range

from 0.5 mm to 1.00 mm from the foramen, how do we find it? I believe electronic apex locators (EAL) have contributed greatly in making WL determina-tion more scientifically based. No longer do we have to engage in the foolishness of evaluating a treat-ment by the aesthetic proximity of obturating ma-terials to the radiographic apex. It’s worth repeating: the apex has nothing to do with WL — it’s all about the foramen. This then begs the question — why are the electronic devices called apex locators?

Apex locator is a poor name, and the manufactur-ers should call them what they are — foramen (or constriction) locators. I recommend we use elec-tronic foramen locator (EFL) and get rid of the term apex locator from here on.

During my teaching years, we evaluated ra-diographic “dead-on the apex” obturations. When the teeth were extracted or viewed during surgical retreatment, the dead-on’s were overfills most of the time. I had to constantly remind students of this fact (and proved it during their training with extracted teeth). Blasting through the constriction to or slightly beyond the foramen and obturating to that point for an aesthetically pleasing X-ray is not scientifically justified.

Knowing the limitations of radiographs for WL determination, let’s see how electronic foramen locators provide greater accuracy. As with all elec-tronic devices, carefully read the instructions. But if they say that the activation of the “bells, lights or whistles” tells you the file tip is at the apex, isn’t that a problem? Since the apex is not the end of the canal, exactly where is the tip? How do we solve this dilemma and make EFLs clinically useful? Un-fortunately, we have to do what the manufacturers should have done. If the alarms indicate the tip is at the apex but we think it’s at the foramen, we should subtract 0.5 mm to 1.0 mm from the file insertion length to get WL. If the alarm is indicating apex but we believe the tip is actually at the constriction, then we should use that for WL. And finally, if the manual says that the bells, lights or whistles go off at the constriction, you will have to confirm the ac-curacy of that statement. You may have to do some fine-tuning as you gain practical clinical experience with your specific device. A little practice and careful observations while using your EFL will be required.

The good news is that in spite of their shortcom-ings, EFLs provide consistently better accuracy than X-rays. They also should help resist the temptation of indulging in “aesthetodontic” contests. In our lectures and writings we could show X-rays of cases that appear “short” (but are not) without worrying

Fig. 2d_Distal canal of mandibular molar cross-sectioned 1 mm from

apex. WL was correct, but WW was not because the final instrument size

was too small. The case failed.

Fig. 2e_Example of a “closing the door” obturation. Compare with

Figure 2d.

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10 I


about our work being judged inferior. All we would have to do is advise the audience beforehand that all WL were 0.5 mm to 1.00 mm from the end of the canal using the accuracy of an electronic foramen locator rather than the inaccuracy of an X-ray.

Alternative technique for WL determination

I give credit for this technique to Bill Wildey, the co-inventor of LightSpeed™ (Fig. 3a). Wildey uses LightSpeedLSX™ instruments (Discus Dental, Culver City, Calif.) to fine-tune WL. He starts with the estimated length given by the EFL; he then goes 1–2 mm beyond that length with the LSX rotating in the handpiece. The small size of the LSX #20 blade usually passes easily through the constriction

because the average diameter of the constriction is roughly #30. Depending on the actual diameter of the constriction (if one exists), the LSX #25 or #30 usually engages the walls of the constriction and a “popping” sensation is felt when the blade goes through the constriction. This tactile feedback gives the exact location of the constriction and the desired location of WL. The key is to advance the instruments very slowly to feel what’s happening in the canal. If a constriction is not present, the popping sensation will be felt passing through the foramen.

Larger LSX sizes, if advanced slowly (recom-mended technique) to the same WL, will allow for the development of an apical stop (matrix). Once developed, the LSX would have to be pushed hard to force it past the stop. Of course, demolishing the constriction where the stop is located (the WL) is not recommended. The apical stop confines our fills to the WL and helps minimize the incidence of overfills.

Notice the length marking rings on the shank of the LSX (Figs. 3b, 3c). I can assure you that significant time savings (and greater accuracy) is possible if you use the rings in lieu of rubber endo stops. In fact, Wildey recommends you have your assistant remove the stops before bringing them chairside to force yourself to make the transition.

ConclusionIn our subconscious minds, we are aware there is

a biologic tolerance to WL. Cases obturated a little short (or a little long) are usually successful when everything else is done correctly. WL need not be perfect for a successful outcome (biologic toler-ance), but the tolerance for an inaccurate WW is not so generous. Avoid the temptation of indulging in “aesthetodontic” contests. The endodontic com-munity should agree to a WL that ranges 0.5 mm to 1.00 mm from the foramen (not apex) and move on to more important issues.

I recommend all manufacturers use the term electronic foramen locator (EFL) rather than apex locator to describe these devices. EFL manufactur-ers should eliminate ambiguous markings on their devices and simply pinpoint only the foramen. Den-tists would then “do the math,” thereby choosing a termination point that is either 0.5 mm or 1.0 mm short of that location. And finally, emphasis should be placed on cleaning the main canal as well as pos-sible (correct WW) close to the constriction/CDJ. Doing so closes the door, prevents bacteria/toxins from contaminating apical tissues and increases the chances of endodontic success.

Smart Endodontics™ offers many helpful tips. To learn more, please call Discus Dental at (800) 817-3636. Request the free CD showing what Smart Endodontics is all about.

I wish to thank Steven S. Senia, BSIE, MBA, for his valuable contribution to this article.

References1. Glossary of Endodontic Terms. American Association of Endo-

dontists 2003, 7th Ed. Chicago, IL.2. Yury Kuttler. Microscopic investigation of root apexes. JADA

1955; 50: 544–52.3. Juan H, Gutierrez G, and Patricia Aguayo. Apical foraminal open-

ings in human teeth. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995; 79: 769–77.

4. Mandell et al. Principles and Practice of Infectious Diseases. Churchill Livingstone, 5th Ed, 2000.

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Fig. 3b_Length-marking rings on the shank can be used as an alternative to rubber endo stops (25 mm LSX).

Fig. 3c_Length-marking rings on 21 mm LSX.

Fig. 3a_LightSpeedLSX™ NiTi rotary instruments with a very short

blade and non-cutting shaft.

_About the author roots

E. Steve Senia, DDS, MS, BSDr. E. Steve Senia earned a DDS degree from Marquette University in 1963. He re-entered the Air Force (previously served as a pilot) and completed a GPR residency. In 1969, he received a MS and Certificate in Endodontics from Ohio State University. He served in the Air Force and retired in 1981 as a colonel and chairman of endodontics at Lackland AFB, Texas. He then became professor and director of the Endodontic Postdoctoral Program at the Uni-versity of Texas Dental School at San Antonio. He retired in 1992. Senia is a diplomate of the American Board of Endodontics. He is a former member of the Editorial Board and the Scientific Advisory Panel of the Journal of Endodontics, an editorial advisor for the Journal of Endodontic Practice and a consultant for the NASA Space Program. He has lectured and published extensively and is the co-inventor of the LightSpeedLSX™ root canal instrumenta-tion and SimpliFill® obturation systems. You may contact Senia at [email protected].

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I research_ obturation

Abstract

Fiber obturators have been introduced into endodontics, but there are few reports of their efficacy compared with standard obturation materials. This study evalu-ated the leakage resistance of fiber obtu-

rators compared with other obturation materials. Sixty-four human single-rooted teeth, with 20

mm average working length, were used for the study. Access was prepared coronally and patency confirmed with a hand file. The canals were instrumented to apical size ISO #40 with NaOCl irrigation, paper point dried, rinsed with 17 percent EDTA solution, re-dried and divided into eight groups of N=8. They were ob-turated as follows: 1) InnoEndo fiber obturator with InnoEndo adhesive and resin sealer. 2) InnoEndo fiber obturator with a self-adhesive resin sealer. 3) Fibrefill fiber obturator with Fibrefill adhesive and resin sealer. 4) Gutta-percha with Endorez resin sealer. 5) Endorez cone with Endorez resin sealer. 6) Resilon cone with Endorez resin sealer. 7) Gutta-percha with ZOE sealer. 8) Gutta-percha with AH26 sealer.

A PVC-covered copper wire was placed coronally

into each tooth in contact with the obturation mate-rial and sealed in place with sticky wax. The exteriors of the teeth and the wax-wire junctions were sealed with three layers of nail varnish with care taken to en-sure that the apices were patent. The teeth then were immersed in 0.9 percent NaCl solution together with a stainless steel counter electrode. A 20 V dc voltage was connected between the stainless steel and each tooth in turn, and current flow determined by voltage drop across a standard resistor (100 Ω) in the circuit. Current flow in the circuit was observed for 30 days and ANOVA and Scheffé testing were used to compare the leakage currents and identify any statistically sig-nificant differences in the leakage behavior.

All specimens showed a progressive increase in leakage with time. The specimen leakage fell into three groups; the least leakage was found with obturations 1, 2, 3 and 5, the greatest leakage with obturations 4 and 8, with obturations 6 and 7 being intermediate.

The data indicate that fiber obturation and a new cone/sealer system provide the best canal obturation as evidenced by the leakage behavior.

IntroductionLeakage can be a hidden factor in endodontic

failure in that percolation at the margins of a res-toration may be long standing before its effects are apparent to the patient or the dentist. In fact, various studies indicate that significant leakage may occur within two days following exposure of teeth with endodontically treated root canals to artificial and natural saliva, leading to complete bacterial leakage.1

In vitro studies likewise indicate that dye leakage can occur in as few as three days.1 It has also been shown that gutta-percha does not offer an effective barrier to crown-down leakage when exposed to the oral environment due to poor bonding with various sealers.1 Additional studies have indicated that gutta-percha will allow bacterial leakage, although the use of adhesive obturation materials can significantly slow or stop coronal-apical bacterial migration.1

Nevertheless, despite its limitations, gutta-percha in combination with various sealers traditionally have

roots1_2009

The leakage resistance ofendodontic fiber obturatorAuthors_Gregori M. Kurtzman & J. A. von Fraunhofer, U.S.A.

Fig. 1_After preparation and obturation, a length of PVC-covered

copper wire was placed coronally into each tooth in contact with the obturation material and sealed in

place with sticky wax.

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14 I roots1_2009

I research_ obturation

been used for endodontic obturation. In recent years, however, novel adhesive systems

have been developed in an attempt to improve leak-age resistance. Fiber obturators were introduced to the market several years ago as a method to address the separate steps of obturation and post placement. These unique obturators allow the practitioner to obturate the canal and place a fiber post in a single

step, thus decreasing the possibility of apical leakage compared to performance of these two stages when performed at separate appointments. Ideally the best

time to completely seal the canal system and prevent coronal leakage issues is at the time of canal obtura-tion when a rubber dam is already in place.

The present study compared the leakage behavior of the recently introduced InnoEndo fiber obtura-tion system compared to that found with traditional materials (gutta-percha used in combination with both AH26 and zinc oxide eugenol [ZOE] sealants) and the newer resin obturation materials. Leakage was assessed using an electrochemical methodology,1,2,3

this approach being adopted because of its accuracy, convenience and high correlation with traditional dye leakage studies.1

Methods and materialsSixty-four human single-rooted teeth, with 20

mm average working lengths, were used in the study. Access was prepared coronally and patency confirmed with a hand file. The canals were instrumented to apical size ISO #40 with sodium hypochlorite (NaOCl) irrigation, paper point dried, rinsed with 17 percent EDTA solution and re-dried before being randomly divided into eight groups of N=8.

The teeth were obturated as follows: IN1: InnoEndo fiber obturator with InnoEndo ad-

hesive and resin sealer.IN2: InnoEndo fiber obturator with a self-adhesive

resin sealer.Fibrefil: Fibrefill fiber obturator with Fibrefill adhe-

sive and resin sealer.GP-ER: Gutta-percha with Endorez resin sealer.ER-ER: Endorez cone with Endorez resin sealer.

Fig. 3_All specimens showed a progressive increase in leakage

with time.

Fig. 2_The teeth were immersed in 0.9 percent NaCl solution together

with a stainless steel counter electrode. A 20 V DC voltage was connected between the stainless steel and each tooth in turn, and current flow was determined by voltage drop across a standard

resistor (100 Ω) in the circuit.

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ER-RES: Resilon cone with Endorez resin sealer.GP-ZOE: Gutta-percha with ZOE sealer.GP-AH26: Gutta-percha with AH26 sealer

(DENTSPLY DeTrey GmbH, Konstanz, Germany).

After preparation and obturation, a length of PVC-covered copper wire was placed coronally into each tooth in contact with the obturation material and sealed in place with sticky wax (Fig. 1). Thereafter, the tooth/wax junction and all external surfaces of the teeth were sealed and insulated with three layers of nail varnish. Care was taken to ensure that the apices of the teeth remained patent.

The teeth then were immersed in 0.9 percent NaCl solution together with a stainless steel counter elec-trode. A 20 V DC voltage was connected between the stainless steel and each tooth in turn, and current flow was determined by voltage drop across a standard resistor (100 Ω) in the circuit (Fig. 2). Current flow in the circuit was observed for 30 days. One way ANOVA with post hoc Scheffé testing at an a priori = 0.05 was used to compare the data and identify any statistically significant differences in the leakage behavior.

ResultsAll specimens showed a progressive increase in

leakage over time (Fig. 3). Statistical analysis indicated that there were no differences (p>0.05) between the groups, primarily because of the large standard devia-tions within the sets of data (Fig. 4). Nevertheless, the trends in behavior indicated that specimen leakage fell into three groups.

The greatest leakage was found in teeth obturated with gutta-percha with Endorez resin sealer and those obturated with gutta-percha and AH26 sealer — that is, obturations 4 and 8.

The least leakage was found with teeth obturated with an InnoEndo fiber obturator and InnoEndo ad-hesive and resin sealer, an InnoEndo fiber obturator with a self-adhesive resin sealer, an Endorez cone with Endorez resin sealer and a Fibrefill fiber obturator with Fibrefill adhesive and resin sealer — specifically, obturations 1, 2, 3 and 5. Teeth obturated with gutta-percha with Endorez resin sealer and those obturated with a Resilon cone with Endorez resin sealer — obtu-rations 6 and 7 — were intermediate in behavior.

DiscussionMethods for the study of leakage may be divided

into three methods — dye penetration, bacterial penetration and electrophoresis. Both dye and bacte-rial penetration methodology provide a qualitative result. The results observed are either black or white, the material leaks or it doesn’t leak. These methods don’t inform us to what degree the material leaks. Dye penetration studies will tell us there was dye leakage along the canal, but to what degree this is clinically significant has been debated as the dye molecule is larger than the bacteria associated with endodontic leakage seen clinically. Bacterial leakage studies were an answer to that question. If the solution in the api-cal chamber of a two-chamber model became turbid, then it was an indication that bacteria penetrated the canal system. But again, this is a qualitative result that

Fig. 4_Statistical analysis indicated that there were no differences (p>0.05) between the groups, primarily because of the large standard deviations within the sets of data.

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Iresearch_ obturation

does not inform us how leakage compares between materials, only that it did leak and when leakage was visible to the eye. Electrophoresis is currently the only method testing leakage behavior that is able to provide a quantitative result, allowing the determination how much different materials leak. This methodology also removes viewer bias as seen with the other meth-odologies. Leakage is measured with an electronic apparatus and is not dependant on the viewer saying he or she could see a result (visible dye shown along the canal’s length when the specimen was sectioned or turbidity seen on the media solution).

Endodontic leakage studies invariably show a scatter in leakage behavior, as evidenced by the large standard deviations in the leakage data. All materials will leak more over the initial period, and leakage be-havior will plateau during the first 30 days then remain fairly consistent thereafter. Nevertheless, the leakage found in the present study for gutta-percha with Endorez resin sealer obturation and teeth obturated with gutta-percha and AH26 sealer was comparable, if somewhat greater than, the findings of other leak-age studies.1

The leakage found for fiber-obturated teeth was similar to that observed with other modern obtura-tion techniques and showed a significantly better leakage resistance than gutta-percha with either ZOE or AH26 sealers.

The findings of this limited in vitro study indicate that the use of fiber obturators combined with newer adhesives holds great promise for achieving consis-tent leak-free root canal obturation.

References1. Khayat A, Lee SJ, Torabinejad M. Human saliva penetration of

coronally unsealed obturated root canals. J Endod. (1993) 19(9): 458–461.

2. Swanson K, Madison S. An evaluation of coronal microleakage in endodontically treated teeth. Part I. Time periods. J Endod (1987) 13(2): 56–59.

3. Cohen S, Burns R. Pathways to the Pulp. 8th edition, CV Mosby, New York, 2001.

4. Britto LR, Grimaudo NJ, Vertucci FJ. Coronal microleakage as-sessed by polymicrobial markers. J Contemp Dent Pract. (2003) 4(3):1–10.

5. Jacobson SM, von Fraunhofer JA. The investigation of microleak-age in root canal therapy. Oral Surg Oral Med Oral Path (1976) 42: 817–823.

6. Mattison GD, von Fraunhofer JA. Electrochemical microleakage study of endodontic sealer/cements. Oral Surg Oral Med Oral Path (1983) 55: 402–407.

7. von Fraunhofer JA, Fagundes DK, McDonald NJ, Dumsha TC. The effect of root canal preparation on microleakage within endo-dontically treated teeth: an in vitro study. Int Endodont J (2000) 33: 355–360.

8. von Fraunhofer JA, Adachi EI, Barnes DM, Romberg E. Effect of tooth preparation on microleakage behavior. Oper Dent (2000) 25: 526–533.

9. von Fraunhofer JA, Klotz DA, Jones OJ. Microleakage within endo-dontically treated teeth using a simplified root canal preparation technique: an in vitro study. Gen Dent (2005) 53: 439–443.

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Gregori M. Kurtzman, DDS, MAGD, DICOIDr. Gregori M. Kurtzman is in private general practice in Silver Spring, Md., and is a former assist-ant clinical professor at the University of Maryland School, Baltimore College of Dental Surgery, Department of Endodontics, Prosthetics and Operative Dentistry. He has lectured both nationally and internationally on the topics of restorative dentistry, endodontics and dental implant surgery and prosthetics. He has published over 130 articles in peer-reviewed publications on numerous dental topics. He is a consultant and evaluator for several dental companies. He has earned fel-lowships in the Academy of General Dentistry, the International Congress of Oral Implantologists, the Pierre Fauchard Academy and the American College of Dentists and masterships in The Academy of General Dentistry and the Implant Prosthetic Section of the International Congress of Oral Implantologists. He can be contacted at [email protected].

J. Anthony von FraunhoferDr. J. Anthony von Fraunhofer is professor emeritus at the University of Maryland School of Dentistry. He has a BSc in chemistry, an MSc and PhD in metallurgy with Chartered Scientist, Chartered Chemist and Chartered Engineer designations from the United Kingdom Science Council. He holds fellowships in the Academy of Dental Materials, ASM International, the Institute of Corrosion and the Royal Society of Chemistry. After several years of industrial research and development, von Fraunhofer joined the Institute of Dental Surgery, University of London and eventually chaired the Department of Biomaterials Science. He was recruited to the School of Dentistry, University of Louisville in 1978 and moved to the School of Dentistry, University of Maryland in 1994. von Fraunhofer has mentored 14 PhD and 120 MS degree candidates, and he has written over 400 scientific papers, 11 books and contributed chapters to 12 monographs. He has made over 140 research presentations at national/international meetings and lectured and presented courses in the United States, England, Continental Europe, North Africa and the Middle East. His fields of interest include biomechanical properties of materials; dental cutting; wound closure devices and wound healing; degradation, wear and corrosion of materials in the biosystem and in industry. He can be contacted at [email protected].

_About the authors roots

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18 I roots 1_2009

I trends_K3 rotary nickel titanium instrumentation

Among the options available, since the introduction of rotary nickel titanium (RNT) instrumentation, choosing be-tween many existing RNT systems has, largely, been a decision between

safety and efficiency. Some instruments cut well but tended to transport canals. Others created less transportation and are relatively safer, but also less effective at shaping dentin.

Complicating matters, there is no literature-based proven superiority of one RNT file system over an-other available at this time. As a result, selection of one RNT file system over another has been primarily empirical and, for many, been based more on tactile feel and ease of cone fit after preparation than any measurable scientific parameters. Each file has its own learning curve, some steeper than others. Mak-ing decisions even more complex, various file systems have been introduced with different technique and tactile recommendations. In essence, each RNT file is unique in many ways based on a number of factors, including design, use recommendations, etc. For example, there are variations among some systems (among many things) in the:

a. Number of recommended uses.b. Type of tactile insertion (pecking motion, single

insertion, multiple insertion, etc.)c. Method of use, i.e., crown down method, step

back method, and/or using a hybrid technique employing both concepts.

d. Recommended rotational speeds. Recom-mended rotational speeds vary from approxi-mately 300 to 2,000 rpm.

Coincident to the above, there is debate in the endodontic community as to the ideal master apical file (MAF) size, a debate that has a direct relationship to the capabilities and limitations of the given RNT file system. Some file systems may not be flexible enough to get around severe curvatures in larger tapers. With some systems, the MAF possible may be limited by the available file sizes. For example, if a file system is available to only a #40 tip size (or some similar diameter) that is the limiting factor imposed onto the clinician, irrespective of what the literature might suggest as optimal.

RNT file systems also differ based on the following attributes (among others):

1. Cross-sectional design and degree of sym-metry.

2. Presence or absence of radial lands.3. Presence or absence of a positive, neutral or

negative cutting and rake angle.4. Whether the file was ground, stamped, or

manufactured via a different method.5. Flute width and flute depth.6. Helical angle.7. Presence or absence of reliefs behind the radial

lands.8. Electro polishing.9. Active versus non-cutting tips.

Fig. 1_The cross section of the K3 RNT.

Fig. 2_K3 in longitudinal cross section.

K3 rotary nickel titanium instrumentation: Blending safety and efficiencyAuthor_ Gary Glassman, Canada

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trends_K3 rotary nickel titanium instrumentation I

10. Fixed tapered, non-tapered, or viable tapers.11. Length of the flutes on the file in longitudinal

section.It is noteworthy in comparing RNT file designs

that the larger the diameter of the file, the greater the file’s resistance to torsional forces. Alternatively, larger files resist cyclic fatigue less well. The smaller the diameter of the file, the greater the resistance of the file to cyclic fatigue, and the resistance to torsion is diminished. In essence, one aspect of determining safety in choosing a RNT system is also a balance of choosing the correct diameter tip size and taper of the RNT file for the particular degree of curvature to optimally resist the forces of torsion and cyclic fatigue.

With the above introduction, how then is the cli-nician to make a selection of a system that cuts well, resists breakage and does not transport canals? I have found that the K3 RNT system from SybronEndo, Or-ange, Calif., is flexible, durable and fracture-resistant, combining these features with excellent tactile con-trol. In short, K3 bridges the gap between safety and efficiency.

Due to the scope of this paper, it is not possible to compare and contrast K3 in all of its design charac-teristics to all of the other brands available in North America. This notwithstanding, the primary design features of K3 are described here.

1) Cross-sectional design and degree of symmetry. K3 is asymmetrical in all its cross-sectional design characteristics. The more symmetrical the file, the more likely the file will tend to “screw in” to the ca-nal. The intention behind this asymmetry is that the clinician must power the file and not allow the file to “screw in.” The asymmetry gives the clinician greater tactile control over the file during insertion. Asymme-try creates one of the hallmarks of K3, there is little no tendency for “screw in.” The clinician powers the file moving apically and does not have to be concerned that the file will grab in the canal and propel itself apically (Figs. 1, 2).

2) Presence or absence of radial lands. Radial lands are placed on the file to center the file, minimize transportation and to provide metal mass behind the cutting edge of the flute as it rotates.

3) Presence or absence of a positive cutting angle. K3 is the only file in North America that has a posi-tive cutting angle on the flutes. Other RNT systems in North America are designed to cut by a scraping motion that requires the advancing edge of the file to remove dentin passively.

4) Whether the file was ground, stamped or con-structed via a different method. The grinding of nickel titanium creates microcracks on the surface of the nickel titanium wire it is made from. The microcracks can propagate if the file is subjected to cyclic fatigue forces or to excess torsion. Lightspeed (Discus Dental, Culver City, Calif.) makes the only non-ground and

Fig. 3

Figs. 3a–3c_The K3 rotary nickel titanium file system (SybronEndo, Orange, Calif.) — the Procedure Pack, the G-Pack and the VTVT Pack

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non-tapered RNT file at this time, which is stamped. All other RNT files are ground with the limitations that microcracks are created. K3 overcomes many of the limitations imposed by these microcracks due to the design characteristics of the file (lack of symmetry, radial lands, non-cutting tip, etc.)

5) Flute width and flute depth. Flute width and depth increases for K3 as the clinician moves away from the tip of the file. Such increasing width and depth provides space for chips derived from cutting. Such channeling of debris reduces torsion.

6) Helical angle. K3 has a greater number of flutes at the distal 8 mm of the file that makes the apical portion of the file as flexible as possible and resistant to fracture. This also provides more cutting flutes at the portion of the file where they are needed most during function.

7) Presence or absence of reliefs behind the radial lands. Two of the three radial lands of K3 are relieved to reduce the friction of the file against the canal walls and to allow more room for chip debris as it is formed.

8) Electro polishing. K3 is not electropolished. While advocated by some, electropolishing can dull the cutting edges of the file as well as change the surface structure of the metal to varying degrees.

9) Active versus non-cutting tips. K3 has a non-cutting tip. Any RNT file can fracture when used inappropriately. Empirically, a lack of cutting at the tip of K3 is borne out by the fact that although rare, when K3 might fracture, it usually does not fracture 3–4 mm at the tip.

10) Fixed tapered, non-tapered, or viable tapers. K3 is a fixed tapered instrument. This means that the final prepared taper and tip size is inherently built into the file. This is significant because some other file designs require that the clinician blend several (po-tentially many) RNT files to create a continuous taper from the orifice to the apex. With K3, if a 0.06 #30 or 35 file is taken to the true working length (TWL), the preparation is final and ready to obturate for an aver-age molar tooth (unless the clinician desires to create larger apical diameters) and blending with additional RNT files is not necessary to create the final ideal prepared canal shape.

K3 is available in six tapers: 0.12, 0.10, 0.08, 0.06, 0.04, and 0.02. The 0.12, 0.10, and 0.08 are available in

a 25-tip size and are generally used as orifice openers. The 0.02 K3 is available in tip sizes of #15 to 45. The 0.04 is available from #15 to 60. The 0.06 K3 is avail-able from 15 to 60. K3 is packed into three different pack configurations, the Procedure Pack, the G Pack and the VTVT Pack.

The Procedure Pack contains either a 0.06 or 0.04 taper:

0.10 .25 tip 17 mm0.08 .25 tip 17 mm0.06 (.04) 40 tip 21 or 25 mm0.06 (.04) 35 tip 21 or 25 mm0.06 (.04) 30 tip 21 or 25 mm0.06 (.04) 25 tip 21 or 25 mm

The G Pack contains:0.12 25 tip 17 mm0.10 25 tip 21 or 25 mm0.08 25 tip 21 or 25 mm0.06 25 tip 21 or 25 mm0.04 25 tip 21 or 25 mm0.02 25 tip 21 or 25 mm

The VTVT (variable taper, variable tip) Pack contains:0.10 25 tip 21 or 25 mm0.08 25 tip 21 or 25 mm0.06 35 tip 21 or 25 mm0.04 30 tip 21 or 25 mm0.06 25 tip 21 or 25 mm0.04 20 tip 21 or 25 mm

There is no inherent or functional superiority of any one given pack configuration over another. Choosing any particular pack configuration over any other is a matter of clinician preference. The above statement notwithstanding, common empirical rea-sons for favoring one pack over another are listed here in discussion of the configurations.

1) The Procedure Pack is generally used in a straight crown down method, in essence using the files from larger tapers to smaller and from larger tip sizes to smaller. Because of the diminishing tip sizes, each K3 file should and does advance slightly api-cally relative to its precursor as it is inserted (which is inherently crown down). For straight canals and mild to moderate curvatures, as would be treated by most

Fig. 4_The new and improved M4 handpiece (SybronEndo, Orange,

Calif.)

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general practitioners, this is an excellent choice for a single pack configuration (Fig. 3a).

2) The G Pack is preferred by some because the files may progress more rapidly toward the apex than with some of the other configurations. Diminishing taper (as opposed to diminishing tip sizes) allows the K3 file to move apically with efficiency. Some believe, with various tapers, that this pack can treat a slightly greater range of anatomy than with the Procedure Pack (Fig. 3b).

3) The VTVT Pack is favored by some because with the variation in taper, with progressive insertions, torsional stresses on subsequent files decrease due to minimized engagement relative to a reinsertion of the taper. Many endodontists favor the VTVT Pack for this reason (Fig. 3c).

4) K3 is used either crown down or step back. When using K3 crown down, the file is used from larger tapers to smaller or from larger tip sizes to smaller. Moving down the root, the given K3 files are advanced until the clinician reaches the estimated working length (EWL), and then the TWL is taken with an elec-tronic apex locator and the preparation finalized.

If K3 is used step back, the clinician uses smaller K3 files initially in an attempt to reach the EWL and establish TWL as rapidly as possible with an electronic

apex locator. For example, if the clinician were to use a VTVT step back and the 0.04 0.20 K3 reached the EWL after the orifices were shaped, the clinician would then advance up the canal from the smaller tapers and tip sizes to larger to the desired final tip size and taper, i.e., a reverse order of the crown down technique.

In any event, it is vital that the clinician use the correct tactile control of the K3 (as with any RNT file) moving either crown down or step back to minimize over engagement and uneccessary fracture risk.

Tactile control 1) Passive gentle insertion. If the file resists ad-

vancement, undue pressure is not put on the file to move apically.

2) Minimal engagement to avoid taper lock. Ide-ally, each K3 insertion will cut 1–2 mm of dentin and after irrigation and recapitulation, the next K3 in the sequence is inserted.

3) Creation of a glide with hand files. Manual pre-flaring of a canal with hand files give the K3 (and all RNT files) a path to track to avoid debris blockage and locking of the tip in a previously unexplored portion of the canal.

4) K3 is never left stationary in the canal. The file is either inserted or withdrawn, but never left rotating at the same level.

5) K3 is inserted in 2–3 seconds to resistance and then withdrawn, the file is not arbitrarily pushed api-cally if it does not want to progress. The motion is con-tinuous and controlled and engagement of the flutes of the file should be minimized to the greatest extent possible, ideally to 1–2 mm per insertion. The same K3 is never reinserted repeatedly to the same level in the canal. There is no value in such a motion.

6) The M4 Safety handpiece is an excellent adjunct to the K3. The M4 is a reciprocating handpiece attach-ment that can take hand K-file, reamer, or Hedström files (among others) and move the files alternatively 30 degrees clockwise and 30 degrees counterclock-wise. The M4 fits onto any E type attachment of an electric motor. The M4 saves time, hand fatigue and makes predictability a hallmark of initial hand file negation of canals. For example, if a MB2 canal is narrow, has multiplanar curvature and is difficult to initially negotiate to the EWL, use of the M4 can make enlargement of this space simple and predictable to the size needed for a glide path. In clinical practice, the #6 hand K file is placed to the EWL, which clinically can often be felt as a pop as the hand K file exits the apical foramen just beyond the minor constriction. Once the #6 drops to length, the file is left in the tooth and the M4 is placed onto the hand file under the rubber dam and in the tooth. With a full depression of the foot pedal and the motor set on 900 rpm and the 18:1 setting, the M4 is activated and the file will reciprocate clockwise and counterclockwise as noted

Figs. 5a–7b_Clinical cases treated with the K3 as described.

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above. With amplitude of 1-3 mm for approximately 15 seconds, the file is moved vertically and apically with a gentle and passive motion. Usually, in ap-proximately this period the initially restrained #6 is able to move freely in the canal. The orifice of the canal is irrigated and the canal recapitulated. Then a #8 is placed and the process repeated, a #10 is then used, etc. until the desired initial diameter is present. If the ideal initial negotiating file is a #8 or #10 based on the initial anatomy of the canals, these files can certainly be used first instead of the #6. It is difficult to fracture a file with an M4; the technique is very safe and highly effective (Fig. 4).

Expanded K3 functionality1) 0.02 tapered K3 files offer a powerful arsenal

of options, especially in negotiating several apical third curvatures. Clinically, if, for example, a canal has a glide path created with the M4, the 0.02 #15 K3 can be brought into the canal to the EWL or TWL. The initial enlargement of the canal path that is made in this manner with the 0.02 #15 can be enlarged to a #20 with the 0.02 #20 K3. This creates an excellent pathway for the subsequent sequence of K3 instru-ments that will be used, irrespective of the pack con-figuration or whether the sequence is crown down or step back in nature.

2) K3 can create larger apical diameters as desired. Since the 0.04 tapers are available to a #60, the 0.06 is available to a #60, and the 0.02 is viable to a #45, K3 can be used to prepare apical diameters of virtu-ally any diameter short of an open apex (i.e., 60 and above). This flexibility is not a common feature of the RNT systems available on the market. The value of this functionality cannot be overstated as the endodontic literature is very clear that larger final prepared api-cal diameters create cleaner canals relative to smaller ones.

3) K3 can be rotated at a wide variety of speeds depending on the wishes of the clinician. SybronEndo recommends that K3 be rotated at approximately 350 rpm, but some have advocated its use at up to 900 rpm and faster for removal of gutta-percha in retreatment (up to 1,500 rpm). What is clear is that if the tactile control over K3 is correct, the files can be rotated at higher speeds than 350 and done so very efficiently.

K3 FAQCan you run K3 with any type of electric motor?

Does K3 have to be used with torque control? K3 can be used with any brand of electric motor,

corded or cordless. K3 can be used with torque con-trol, but it does not have to be. Many endodontists use K3 (and other RNT files) with the torque control off.

Can K3 files be used in coordination with other RNT file brands?

While K3 is a complete system, K3 can be combined

with any RNT brand desired.

What is the most common sequence of K3 use?Common sequences of K3 include:a. crown down from larger tapers to smaller and

from larger tip sizes to smaller, if the tactile control is correct.

b. Step back, using K3 from smaller to larger tapers.

Literally, for both of these techniques, the K3 files can be placed from the pack configurations into the sponge in the same order they were packaged and the files are used in this order, crown down (primarily larger to smaller) or step back (primarily smaller to larger) as described here.

In both of these techniques, initial negotiation and creation of a glide path with hand files is essential to precede the K3 in the given portion of the canal being enlarged.

Is K3 stiff?K3 is not inherently stiff. The “feel” of K3 in one’s

hand has no translation to its clinical function. Clini-cally, if K3 is used appropriately (correct rotational speed, method of insertion, engagement, etc.) it is more than flexible enough to handle even the most challenging curvatures.

How many times can I use a K3 file?Individual preferences vary. I generally use my

K3 from 3–5 molar teeth. If there are any wear marks, stretches, kinks, bends, etc., it is discarded im-mediately. Smaller taper and tip sized K3s might be discarded after a single use (0.02 #15 and #20 files) and the larger tapers, a 0.04 and 0.06 above a #20 can be used more often.

Can I match my K3 preparation with gutta- percha points?

Matched K3 gutta-percha is available. The final prepared taper and tip size of the K3 file is matched by a gutta-percha point with little if any adjustment of the cone being necessary.

What do I do if I can’t get a hand file beyond some level in the canal? Do I use K3 to the level of the block-age and then fill at that level? Will this reduce my success?

Part of the answer depends on whether the area of blockage could once be bypassed or not. If the blockage could never be bypassed from the start of treatment, it may or may not be negotiable. If the level of the canal that is now impassable was once negotiable, the blockage has obviously been created by the clinician and the chances improve somewhat that bypassing can be achieved.

If referral is an option, such an event is often an indication for referral, especially, if the given block-

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24 I

age was not present earlier in treatment. Precurving hand files for use in such situations is essential. Such bending (a small J bend at the tip of the file) allows the hand file to negotiate the canal more easily, espe-cially a curved canal. The EndoBender (SybronEndo, Orange, Calif.) is an excellent instrument for this pur-pose. In a canal filled with irrigant and a precurved hand file, the clinician should make every effort to bypass the blockage to regain canal patency. This effort to bypass the blockage may take many hand files and repeated insertions from different orienta-tions to determine if there is any negotatible canal space. There is value, of course, in taking a radiograph to see if visible canal transportation has occurred or perhaps a separated file is blocking the canal, amongst other possible sources of obstruction. If the canal can be subsequently negotiated by hand and the blockage bypassed, the glide path should be reestablished (an M4 would be very helpful for such a task) and the smaller tapers and tip sizes of K3 used first to create a minimal diameter. Subsequently, the final apical preparation of the desired taper and tip size can be created.

How do I know when to stop the preparation? When am I done with K3?

Globally, most clinicians will finish their apical preparation to approximately a #25 or 30, but the rationale and methodology for creating master apical diameters varies widely. There is strong evidence in the endodontic literature that larger apical preparations result in cleaner canals. One method to determine what the ideal master apical diameter might be is to gauge the canal, i.e., determine the initial diameter of the minor constriction of the apical foramen. To gauge the apex, the clinician can determine the hand file that meets resistance at the minor constriction for the apical foramen and from this measurement make a determination of the ideal final prepared diameter. For example, if a #30 hand K file meets resistance at the minor constriction and will not pass with mild pressure, the master apical preparation can be taken to a 45. While this is certainly not an exact science, this allows the canal to dictate the final preparation rather than imposing onto the canal an arbitrary MAF.

Where should I stop the preparation exactly and how is this influenced by K3?

There is no universal agreement about the ideal filling point of obturation. Rationales and method-ologies vary as to the ideal filling point. In practical clinical terms, the minor constriction of the apical foramen is the natural termination point for instru-mentation, irrigation and obturation. The position of the narrowest diameter of the minor constriction is accurately determined by the use of an electronic apex locator and often confirmed with a bleeding point determination. Some would argue that the

ideal position for obturation might be short of the minor constriction and others make a distinction be-tween vital and necrotic cases, with vital cases filled to just short of the minor constriction and necrotic cases obturated to the minor constriction. It is beyond the scope of this paper to comprehensively review these concepts. With tactile control, the use of a bleeding point determination, the electronic apex locator and possibly radiographic information, the position of the minor constriction of the apical foramen can be determined very accurately. With K3’s functionality, preparations can be made with enhanced MAFs to the minor constriction as needed.

What do I do if I want to advance the K3 file in my sequence and it does not want to advance?

As with all RNT files, the K3 should never be forced to move apically. If, for example, using a G Pack, the 0.08 orifice opener has been used to the point of the first curvature and the 0.06 does not want to progress passively beyond this first curvature, the clinician would go to the 0.04 25. This should progress slightly beyond the initial root curvature. If the 0.04 will not allow initial engagement beyond the desired level, the clinician can then move to the 0.02 tapered K3 25, which should easily advance beyond all but the most severe curvatures.

Alternatively, the clinician can create more taper above the point of resistance (by using the 0.12, 0.10 and 0.08 tapered 25 K3) and then attempt to place the .06 again into the root beyond the curvature.

How are irrigation and patency maintenance in-serted into the K3 sequence?

Irrigation and maintenance of patency with hand files (0.08 file size, slightly past the apical constric-tion) are ideally performed after every K3 insertion. Frequent irrigation and patency maintence keeps the canal open and negotiable, thereby preventing apical debris blockages and minimizes the possibility for iatrogenic events. The importance of such irrigation and patency maintenance cannot be overstated in the context of prevention of iatrongic events of all types (separated instruments, ledging, perforation, etc.). Blockages can easily lead to deflection of instruments away from the true canal path and cause iatrogenic issues.

Enlargement should take place with a sequence of insertion, irrigation and patency maintenance. Ide-ally, and especially in difficult curvatures and calci-fied canals, this irrigation and patency maintenance should optimally take place after every K3 insertion.

How do I know when it is time to throw a K3 file away?

If a kink, bend or deformation should appear with K3, it should be immediately discarded. Torsional stresses and cyclic fatigue stresses on files are cu-

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mulative; when in doubt, the file should always be discarded.

Can I use K3 to remove gutta-percha, pastes and warm carrier based products?

Yes. Usually, such procedures are performed by endodontists and done so at enhanced rotational speeds, from 900 rpm to 1,500 rpm. Use of such enhanced speeds requires experience, caution and clinical judgment.

All RNT systems are optimized by the following strategies.

1) Use of a surgical operating microscope (SOM) (Global Surgical, St. Louis, MO, USA). A clinician can never have enough lighting, magnification and visu-alization in endodontics.

2) Manual preflaring of the canal to create a mini-mum #15 sized glide path before RNT insertion. In essence, before a K3 is placed into any canal, the canal has an initial diameter of at least a #15 hand file.

3) Lubrication is essential before insertion of a RNT file. In vital cases with a great deal of pulp, a viscous EDTA gel (File Eze, Ultradent, South Jordan, Utah) is appropriate until at least the greatest bulk of pulp is removed from the canals. After removal of the majority of pulp and the chamber is cleaned, sodium hypochlorite can be used as the primary irrigant in vital cases. In non-vital cases and retreatment, gener-ally chlorhexidine is more commonly used.

4) Straight-line access is ideal. All files, hand and RNTs, should not deflect on insertion into the canals.

5) The clinician must appreciate at all stages of the enlargement process the EWL (and TWL once known) to correlate the position of the RNT file tip to minimize the chances for apical transportation via inadvertent insertion through the minor constriction.

6) The RNT files should be lined up on the sponge in the expected order of use or, alternatively, the

clinician may place each RNT into a handpiece at-tachment. Exchanging the attachments into the handpiece (corded or cordless) is far more efficient than replacing each single RNT into the attachment. While there is an initial investment in attachments, these multiple attachments can save valuable time between instrument switches.

7) Preoperatively the tooth should be evaluated for all foreseeable risks of possible iatrogenic events. Coincident to this evaluation, the clinician should de-termine what the anticipated final taper and tip size of the preparation might be. The final prepared taper is generally a 0.06 taper throughout the length of the preparation for most of the teeth treated in both specialty and general practice. Thus, it is certainly possible that the final prepared taper and anticipated tip size can change after the tooth is opened. It must be remembered that the tooth dictates the shape of the final preparation. The final and taper and tip size are not dictated onto the tooth by the clinician (Figs. 5a–7b).

A comprehensive view of the K3 RNT system has been discussed to allow the clinician to utilize the instrument in clinical practice. Emphasis has been placed on:

1) The instrument is asymmetrical in all of its design characteristics and and, as a result, has little if any tendency to “screw in” as do many designs that are more symmetrical.

2) As with all RNT files, a glide path is advised. The M4 safety handpiece is a very useful adjunct to K3 technique in creating the glide path.

3) K3 can be used crown down or step back. In either event, insertion of the file is gentle, passive and should minimize engagement of dentin.

4) K3 is a complete system from which enhanced master apical diameters can be created for a wide range of clinical anatomies.


Gary Glassman, DDS, FRCD(C)Gary D. Glassman graduated from the University of Toronto, Faculty of Dentistry in 1984 and was awarded the James B. Willmott Scholarship, the Mosby Scholar-ship and the George Hare Endodontic Scholarship for proficiency in endodontics. A graduate of the Endodontology Program at Temple University in 1987, he received the Louis I. Grossman Study Club Award for academic and clinical proficiency in endodontics. The author of numerous publications, Glassman is on staff at the University of Toronto, Faculty of Dentistry in the graduate department of endodontics. A renowned international lecturer on endodontics, Glassman has presented at major dental conferences around the world including the annual conference for the European Society of Endodontology, the Canadian Dental Association, the Ontario Dental Association, the California Dental Association, the Texas Dental Association and the Irish Dental Association. He can be reached through his Web site, www.rootcanals.ca.

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26 I

I trends_ taper and apex locator

Globally, the endodontic questions asked by general practitioners are very com-mon. Two of the most frequent are ad-dressed here. While the specific instru-

ments used to accomplish a root canal may vary, the principles advised in the answers are universal. At the heart of each of the answers is a goal to remove bacteria to the greatest extent possible from the root canal system, obturate the canal system in three dimensions and create a post endodontic coronal seal as soon as possible after treatment. These goals are consistent with the goals of endodontic canal enlargement, which are to: three-dimensionally

clean and shape the canal space from the orifice to the minor constriction (MC) of the apical foramen and do so in a way that minimizes or eliminates the risk of subsequent vertical fracture. Inherent to safe and efficient canal enlargement is adherence to the primary principles of canal preparation (maintain-ing the MC in its original position and size, keeping the canal in its original position and only enlarging it in the shape of a tapered funnel with narrowing cross-sectional diameters). Secondary goals of canal preparation are to prepare a canal that has a taper and size to optimize irrigation and obturation. With these goals as a foundation, the following two clinical questions are answered.

Question 1: How do I know what taper to prepare for a given canal? Does it matter, particularly in the apical third?

This question is clinically more relevant than ever with the introduction of the Twisted File (SybronEndo, Orange, Calif). The TF, due to its manufacture, in-cludes a proprietary process that never cuts across the grain structure of the metal, which allows a flex-ible and highly efficient enlargement of the canal to the MC and does so with greater flexibility and fracture resistance than ever before. The TF is avail-able in five tapers — 0.12, 0.10, 0.08, 0.06 and 0.04. Depending on the anatomy encountered, the TF can prepare a taper of 0.12, 0.10 and 0.08 into the apical

roots 1_2009

Answering two frequently asked clinical endodontic questions: How much taper? How do I troubleshoot my apex locator?

Author_ Richard Mounce, U.S.A.

Fig. 1_The Twisted File (SybronEndo, Orange, Calif.)

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third, far larger than that possible with ground rotary nickel titanium (RNT) instruments (Fig. 1).

Several important points should be made with regard to choosing a taper.

1) Greater taper in preparations removes more tooth structure than less taper, and a greater taper carries with it more risk of strip perforation and long-term risk of vertical root fracture, especially if a root form is enlarged more than absolutely neces-sary (Fig. 2).

2) Generally, greater taper is used in less complex root canal forms. Less taper is used in more complex root forms.

3) Greater taper taken apically increases the chances for cyclic fatigue failure of instruments. In other words, more metal mass in files gives RNT instruments greater resistance to torsional stresses and yet reduces their ability to withstand flexural failure — i.e., failure from cyclic fatigue. With regard to taking instruments of greater taper further apically, it should be remembered that such instruments would have fewer revolutions to failure due to cyclic fatigue, relative to other smaller, less tapered instruments.

4) Use of greater taper prepares larger apical diameters further apically in addition to the taper of the preparation. For example, with a 0.10 tapered instrument, such as the 0.10 TF, which is a 25 at its tip, 1 mm back from the tip, it is a 35 and 2 mm back it is a 45. Such a rapid increase in size has ramifica-tions aside from the risk of strip perforation in that if the instrument is taken beyond the MC it can rapidly transport the MC. Such an event is consistent with apical bleeding, challenges in cone fit, extrusion of sealer and irrigants, etc. Knowing the exact position of the MC as well as having precise control over the position of the RNT file tip at all times are consistent with the most efficient possible use of greater tapers. The converse is also true.

5) Greater tapers, used apically, such as that which are possible with the TF, ideally require that the clinician have an excellent glide path in which to place the RNT. The use of a reciprocating handpiece, such as the M4 (SybronEndo, Orange, Calif.), allows efficient and rapid creation of a glide path relative to its creation by hand.

Generally, but with exceptions (for example, variably tapered RNT file systems), most RNT files are manufactured in 0.12, 0.10, 0.08, 0.06 and 0.04 ta-pers. Except for the TF and the LightSpeed Instrument that is stamped (Discus Dental, Culver City, Calif.), all RNT instruments are ground from a blank of nickel titanium wire. Grinding produces microcracks that can act as the focus points for fracture.

The use of various tapers in different anatomies is discussed below.

A) 0.12 tapered RNT instruments are used prima-

rily as orifice openers and are generally not used to the MC. 0.12 RNT files are generally used only at the orifice and not into the middle third. Whether a 0.12 RNT should be used in the coronal third or just beyond the orifice is entirely case dependent relative to the existing anatomy, width of dentin at the furcation and the RNT instrument considered. In any event, 0.12 RNT files should not be used indiscriminately. Quite the opposite, of the RNT instruments available, regardless of the brand, these files should be used with the utmost caution because of the aforemen-tioned risk of stripping and vertical fracture.

It is very rare that a 0.12-tapered RNT would or should be taken to the MC. However, there are situ-

Fig. 2_Excessive taper that led to a strip perforation in this lower molar.

Fig. 3_Clinical case performed with a single TF instrument.

Fig. 4_Clinical case performed with two TF instruments.

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Fig. 7_The Elements Diagnostic Unit (SybronEndo, Orange, Calif.)

ations where this may be possible and advisable. For example, the TF might be able to be taken into the apical third of some wide-open palatal roots and ca-nines due to its flexibility and cutting ability. As men-tioned though, this would be uncommon. For this to be possible, an excellent glide path would be needed to the MC, irrigation and recapitulation would be mandatory after every file insertion and the canal could not have any apical abrupt curvature — i.e., it must be relatively straight and uncomplicated to the MC. The clinician would know if this was the case through careful evaluation of the initial radiographs as well as the tactile negotiation of the canal by hand in the early stages of canal enlargement.

B) It would be uncommon to take 0.10 and 0.08 tapered ground RNT to the MC. With the TF, 0.10 and 0.08 instruments will be a common master apical taper. Alternatively, 0.06 is a very common taper with ground RNT systems. If a 0.04 TF were to be taken to the MC, it is possible to easily and safely take the canal preparation to a greater taper, either 0.06 or 0.08 TF, case dependent (Figs. 3,4).

To summarize, in wide open, straight and uncom-plicated, non-calcified canals, the 0.12 and 0.10 TFs can be used, as clinically indicated, if inserted pas-sively to the MC. In more intermediate canals, 0.10 and 0.08 TFs are used. “Intermediate” in this context means bicuspids or the mesial roots of many average

Fig. 5_Accurate location of the minor constriction of the apical foramen.

Fig. 6_Lack of accurate working length determination that led to

apical transportation and iatrogenic outcome.

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molar teeth. Whether a 0.10 TF would be used is re-lated to the iatrogenic risk discussed above. Narrow, calcified, curved and complex canals will generally require a 0.08 from orifice to apex with the TF. Canals of extreme complexity will require a 0.06 taper when enlarged with the TF.

When using ground RNT instruments, such tapers cannot be taken to the MC because of their lack of flexibility. For example, in the mesial root of an aver-age molar with ground instruments, the 0.10 may be used at the orifice only, the 0.08 might be taken into the coronal third of the root and the preparation fin-ished with a 0.06 taper. This stands in distinction to a canal preparation with the TF where the entire canal is prepared to a 0.08 taper or 0.10 taper.

Question 2: My electronic apex locator (EAL) sometimes gives me unusual read-ings and I am not sure what to believe. How can I deal with this?

Locating the true position of the MC is an essential landmark within the achievement of an endodontic procedure. If the true position of the MC is located, the clinician has the potential for optimal cleansing and shaping. This has significant clinical ramifica-tions. A multitude of possible iatrogenic issues can be avoided if the clinician will accurately determine the initial position of the MC and take steps to avoid transporting or enlarging the MC; in essence to leave this natural boundary in the root canal space where it was originally. Alternatively, if the MC is moved, transported or changed in any way, iatrogenic out-comes, such as gross overfilling, extrusion of irrigants and sealer, etc., are all much more likely to occur. In addition, the clinician should avoid using RNT files in the apical third without first accurately determining the position of the MC. To use RNT of any tip size and taper in the apical third as pathfinders without first preparing a glide path is the harbinger of separated files, canal transportations and iatrogenic issues of all types (Figs. 5, 6).

The endodontic literature makes several important clinical considerations that can aid in interpreting the

position of the MC and in TWL determination.

Several studies are cited 1) Radiographic means to determine the posi-

tion of the MC should be viewed with caution as radiographs only give the relative position of the file against the root and its relation to the radiographic apex. Radiographs do not tell the clinician the exact position of the MC or really anything about the posi-tion of the file in relation to the apical foramen. The literature (Williams CB, Joyce AP, Roberts S. A com-parison between in vivo radiographic working length determination and measurement after extraction. J Endod 2006;32:624–627) reports that if a file ap-pears short on a radiograph, it is actually closer to the apical foramen than it appears and conversely, when it appears “long” it is actually further from the apical foramen than it would appear to be radiographi-cally. Radiographic working length determination is fraught with potential problems. These problems include developmental errors, angulation errors, and lack of software tools to manipulate and study the images, among other issues. One study (ElAyouti A, Weiger R, Löst C. The Ability of Root ZX Apex Locator to Reduce the Frequency of Overestimated Radio-graphic Working Length. J Endod 2002; 28:116–119) found that using radiographs resulted in a reading that was long approximately 51 percent of the time and that such error was reduced using an EAL. The error is derived from the fact that the apical foramen is often positioned away from the anatomic apex, in essence, introducing error.

2) The endodontic literature (Venturi M and Breschi L. A comparison between two electronic apex locators: an in vivo investigation. Int Endod J 2005;38:36–45) gives weight to my observation below that irrigant in the canal affects the readings and reliability of some machines.

3) Empirically, how an apex locator is used is more important than the specific EAL. In this study (Tselnik M, Baumgartner JC, Marshall JG. An evaluation of Root ZX and Elements diagnostic apex locators. J Endod 2005;31:507–509), the Elements Diagnostic Unit (SybronEndo, Orange, Calif.) was compared with the Root ZX (J Morita, Irvine Calif.). It was found that there was no statistically significant difference between the two units. The above notwithstanding, I have been using the Elements Diagnostic Unit (EDU) for several years in full-time private endodontic practice, and it has functioned extremely well. It is noteworthy that the EDU can also serve as an electric pulp tester aside from just functioning as an elec-tronic apex locator (Fig. 7).

By way of definition, an EAL gives the position of the MC as the file being used in the determination just passes beyond the narrowest diameter of the root canal system at the cementodentinal junc-tion (CDJ). While generally very reliable, there are

Fig. 8_Clinical case treated in the manner described with a bleeding

point confirmation of the position of the minor constriction of the apical

foramen.

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several common challenges when using EALs. While electronic apex locators are marketed as though they can be used with blood, purulence and sodium hypochlorite in the canal (among other solutions), empirically I have found that their accuracy is not as favorable with liquid in the canals — i.e., they func-tion better in a dry canal. In addition, in the event of a faulty reading, the largest file that can reach the MC should be used, the file should not touch the metal of the crown (if one is present), and the first thing that should be done in the event of a faulty reading is for the clinician to check all of the unit connections to make certain that they are inserted correctly.

It is essential to appreciate that an EAL reading should be one of a number of various pieces of con-firming information to alert the clinician as to the true position of the MC of the apical foramen. First off, the clinician should appreciate that the hand file, which just passes the MC, often gives the clinician the feeling of a “pop” as it passes out the apical foramen. The hand file used to accomplish this is small, #6, 8, 10, and is precurved during negotiation of the canal. If the clinician is careful to make note of the position of the initial “pop” of a hand file (if one is detected), he or she will find that this is virtually identical to the position determined by a subsequent “bleeding point” with a paper point and the EAL reading. Feel-ing a tactile “pop” at the MC also has value in telling the clinician that he or she can negotiate the canal to the MC and that if the canal patency is subsequently lost, this was due to something that the clinician did rather than being due to a calcification or other blockage that is related to an anatomical challenge in the root canal system.

While there are as many methods to determina-tion of true working length as there are clinicians, what follows are my common methods.

1) I do not take radiographs during treatment unless there is an imperative reason to do so. From the initial radiographs, an estimate is made of the true working length (TWL), this estimated working length (EWL) is usually very close to the true working length. The EWL is held in mind until the clinician

can negotiate the canal by hand to this level with a small hand file.

2) Once a hand file reaches the EWL, TWL is taken with the EDU for the first time and instrumentation commences with the TF, using a taper as described above. After canal enlargement is completed, the TWL is taken again with the EDU and canal prepara-tion finalized. After the preparation is finished, the EDU is used to reconfirm the TWL. This second deter-mination of TWL is made because the canal will get slightly shorter during preparation, although the loss of length is generally fairly small, 0.5 to 1 mm.

3) After canal preparation is finalized and the EDU is used as noted above, the EDU measurements are confirmed with a bleeding point. The bleeding point is taken with paper points and the position of the MC of the apical foramen is finalized for the purposes of obturation using this method in my hands. The bleeding point is determined using a paper point that just spots with moisture or haemorrhage at the tip, generally about 1 mm at the position of the MC. This spotting is consistent and reproducible.

4) Some clinicians will place the master cone back from the MC by 0.5 to 1 mm to prevent the extrusion of sealer and obturation material. If the position of the MC has been determined accurately, it is optional and not a step that I personally take. Aside from creating the correct shape of preparation to the MC, applying the correct amount of sealer and achieving excellent cone fit and tugback are all methods to prevent extrusion.

The answers to two clinically relevant questions have been discussed to help guide clinicians when making decisions with regard to the final taper of their canal preparation as well as to aid in the preci-sion of the termination point of that obturation. Emphasis has been placed on creating a taper that allows adequate irrigation and obturation, but that does not put the root at risk of a subsequent vertical fracture or strip perforation. In addition, determining TWL in a dry canal and understanding the limitations and capabilities of electronic means of electronic TWL determination are essential (Fig. 8).


Richard E. Mounce, DDSRichard E. Mounce lectures globally and is widely published. He is in private practice in endodontics in Vancouver, Wash. He offers intensive, customized endodontic single-day training programs in his office for small groups of doctors. For information, contact Dennis at (360) 891-9111 or write [email protected].

RO0109_1-52.indd 31 3/5/09 1:16:53 PM

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Once the pulp tissue has become necrotic, the products of cellular degeneration, bacterial toxins and occasionally the bacteria themselves within the canal, spread through the

apical foramen or the various lateral foramina into the surrounding periradicular tissue.

A slow inflammatory process thus begins in the tissue contained within the periodontal ligament. Left to itself, it may manifest in a variety of ways ranging from simple widening or thickening of the ligament to granuloma or cyst.

The increased space of the periodontal ligament in this area is due to resorption of the surrounding bony trabeculae with secondary fusion of the connective tissue of the periodontal ligament with the inter-trabecular connective tissue of the medullary spaces. The fibers of the periodontal ligament, which become disordered and dysfunctional, lose their insertions in the surrounding bone. However, their insertions in the cementum, particularly in the periphery of the lesion, are preserved. The pathological entity commonly known as a granuloma develops in this way. Sometimes, the inflammatory process also in-volves other cellular elements within the periodontal ligament, namely epithelial rests of Malassez, which, when stimulated to proliferate, give rise to a cavity and a radicular cyst.25

In its various clinical manifestations, chronic apical periodontitis is generally asymptomatic. It is usually discovered on routine radiographic checkups, which on occasion is prompted by suspicious discol-oration of the dental crown. The patient may relate a history of acute (pulpitic) pain that spontaneously re-solved or a history of trauma, but he may also present with a completely unrevealing history. Sometimes, a fistula may be present, through which the patient reports having noticed an intermittent discharge of pus (Figs. 1a–f).

roots1_2009

Nonsurgical therapy of mucosal and cutaneous fistulaeAuthor_Arnaldo Castellucci, Italy

Fig. 1a_Preoperative radiograph of the upper left central incisor with a necrotic pulp caused by preceding

trauma.

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The fistula provides a means of continuous drain-age of the lesion. This usually prevents reactivations, either spontaneous or consequent to intervention.

Some authors2,6,10,12,22 are still convinced that the presence of a fistula indicates a more serious lesion that requires special intervention, such as surgical incision and excision of the entire fistulous tract, in addition to extraction of the diseased tooth (Fig. 2).

In fact, the presence of a fistula should be seen as a favorable sign, because it is associated with a number of advantages, so much so that some au-thors3,8,15,23,24,26,31,32 suggest that if there is none, one should be created.

It may be extremely helpful in diagnosis. Opaci-fication of the fistulous tract by the insertion of a gutta-percha cone clearly demonstrates the diseased tooth 16 (Figs. 3a–d). The opening of the fistula may be found on the mucosa overlying the tooth that sustains it, but it may also often be found at a consid-erable distance from the diseased tooth (Figs. 4a–f). Indeed, it may cross the midline, as in cases described by Feiglin9 and Kaufmann.16

In other situations, the fistula may run in the space of the periodontal ligament of the same tooth (Fig. 5). It may even traverse the periodontal ligament of the adjacent healthy tooth,17 thus simulating a lesion of periodontal origin (Figs. 6a–d). In such cases, nega-tive pulp tests performed on the crown of the tooth indicated by the gutta-percha cone inserted into the fistula assist in making the correct diagnosis.

Furthermore, healing of the lesion about one week after cleaning and shaping of the infected root canals without the use of any medications within the canal (Figs. 7a–c) confirms that the diagnosis was correct and testifies to the efficacy of the treatment. This also suggests a favorable prognosis for the lesion.

Fig. 1b_The dental crown is strongly discolored by hemorrhage secondary to the trauma. Note the mucosal fistula.

Fig. 1c_One week following the cleaning and shaping procedure only, the fistula has completely disappeared.

Fig. 1d_Postoperative radiograph: the filling has been performed after determining clinically that the fistula had healed

Fig. 1e_Appearance of the dental crown after bleaching.

Fig. 1f_One year recall.Fig. 1e

Fig. 1b

Fig. 1d

Fig. 1f

Fig. 1c

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Finally, as already suggested, the fistula provides a means of continuous drainage of the suppurative contents of the periapical lesion. This discourages sudden reactivations, either spontaneous or as a result of our intervention.

If the drainage is not continuous, but rather inter-mittent, it is preceded by slight swelling of the area as a result of the increased pressure of pus behind the closed orifice. When this pressure is great enough to rupture the thin wall of soft tissue, the suppurative material issues externally through the small opening of the fistulous orifice.11 This orifice may heal and re-close, only to reopen later. The discharge of pus is never accompanied by intense pain. At most, the patient will complain of slight soreness in that area prior to reopening of the external orifice.

The pus creates a tract in the surrounding tissues, following the loci minoris resistentiae. It may exit at any point of the oral mucosa or even the skin.19

It is not uncommon, particularly in young patients, to find cutaneous fistulae at the level of the mental symphysis, if lower incisors are involved (Figs. 8a–e), or in the submandibular region, if a lower first molar is involved (Figs. 9a–e), or in the floor of the nasal fossa,

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Fig. 2e_The prescription for tooth extraction and the fistulectomy (!)

Fig. 2f_After the removal of the old restoration, it is evident the way the access cavity was

previously made: the pulp horns have been misdiagnosed for

canal orifices and the clinician forgot to remove a big portion of

the roof of the pulp chamber.

Fig. 2a_The endodontic treatment of the upper left first molar is

completely inadequate. A gutta-percha cone is tracing a sinous tract, originating on the palate, in the area

of the missing second molar.

Fig. 2b_The patient received a pantomograph...

Fig. 2c_... a computerizedtomography...

Fig. 2d_ ... and a biopsy(Iperkeratosis and and acute

inflammation!)

Fig. 2a Fig. 2b

Fig. 2d

Fig. 2e

Fig. 2c

Fig. 2f

RO0109_1-52.indd 34 3/5/09 12:29:48 PM

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36 I roots1_2009

if a central incisor is involved.13,30

Cutaneous fistulae, which unfortunately are sometimes treated as though they were independ-ent dermatologic lesions, have the same pathogenic and prognostic significance as mucosal fistulae and require the same therapy.21,33 A review of the literature5,7,18,29 reveals that patients with cutaneous fistulae are sometimes subjected to repeated surgical excisions and biopsies (Fig. 2d) before it is clear that the fistula is none other than an extension of pulp disease in the periradicular tissues.

Trying to treat such lesions with a circular incision of the orifice of the cutaneous fistula and excision of its entire tract, with all the ramifications — par-

ticularly esthetic — of such an intervention, is not consistent with the present standard of care and can be considered pure folly.

These fistulae simply require identification of the diseased tooth, whose root canal system must be cleaned and shaped.

If the tooth presents any obstacles to nonsurgical treatment or retreatment, or if the patient specifically requests surgery, one may proceed surgically, but one’s attention must be directed solely to achiev-ing a retrograde apical seal, and not eliminating the fistulous tract or its cutaneous orifice (Figs. 8a–e). The reason why some authors believe in the need for surgical removal of the fistulous tract lies in the

I trends_ fistulae

Fig. 2g_Postoperative radiograph.

Fig. 2h_The fistula is healed.

Fig. 2i_Six-month recall.

Fig. 3a_Preoperative radiograph of the upper right first and second

molars. Note the round radiolucency between the mesiobuccal root of the

second molar and the distobuccal root of the first. The patient had

presented with a vestibular fistula at the level of the first molar, and

for financial reasons only wanted to retreat the diseased tooth.

Fig. 3b_A gutta-percha cone placed in the fistula indicates that the fistulous tract arises from the

second molar.

Fig. 3c_Postoperative radiograph of the second molar. Note that a small

lateral canal in the mesiobuccal root, which was apparently

responsible for the lesion seen in the preoperative film, has filled up.

Fig. 3d_Five-year recall.

Fig. 2g

Fig. 3a

Fig. 3c

Fig. 3b

Fig. 3d

Fig. 2h Fig. 2i

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Fig. 4a

Fig. 4c

Fig. 4e

Fig. 5

Fig. 4b

Fig. 4d

Fig. 4f

Fig. 6a Fig. 6b

Fig. 4a_This young patient presented with a fistula between the canine and lower right first premolar. A gutta-percha cone has been inserted into the fistulous tract.

Fig. 4b_Radiographically, the gutta-percha cone seems to implicate the lateral incisor as the diseased tooth. All the teeth heretofore identified have responded positively to the vitality tests.

Fig. 4c_Deeper insertion of the gutta-percha cone finally identifies the two lower central incisors as the diseased teeth. Both respond negatively to the various vitality tests.

Fig. 4d_One week after cleaning and shaping, the fistula has closed.

Fig. 4e_Postoperative radiograph.

Fig. 4f_Two-year recall.

Fig. 6b_Preoperative radiograph of the lateral incisor. Note that the lesion “rests” on the mesial side of the root of the adjacent canine.

Fig. 5_Preoperative radiograph of a necrotic lower left second premolar with a fistula opening into the space of the periodontal ligament. A gutta-percha cone has been inserted into the fistula.

Fig. 6a_The periodontal probe disappears in the sulcus of the canine in a patient with good oral hygiene and healthy periodontium in the different quadrants. The canine responds positively to the tests of vitality, while the lateral incisor is necrotic.

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mistaken conviction that it is lined by an epithelium.28

Grossman11 states, however, that such tracts are lined by granulation tissue: in his study, he was unable to identify any epithelium at all.

Bender and Seltzer4 have also made histologic studies of numerous fistulous tracts without finding an epithelial lining.

Other authors1,14,31 agree that the fistulous tract may be lined by flat, multilayered epithelial cells, but that more often it is lined by granulation tissue, with acute and chronic inflammatory cells.

Given the current state of knowledge, there is no reason to recommend surgical removal of such tracts. There is no reason that even epithelium-lined fistulous tracts should not heal after appropriate endodontic therapy.

When it is present, the epithelium may arise from the oral mucosa or proliferating epithelial cells from the periapical lesion. However, there is no correlation between the presence or absence of an epithelium and the clinical appearance of the fistula or its chro-nicity.

In animal experiments, Ordman and Gillman20

have demonstrated that cutaneous sutures may become completely epithelialized if the sutures are left in place for several weeks. Once they are removed, however, the epithelium-lined tract always heals completely.

There is no reason that the same should not hap-pen to the possibly present epithelium of the fistula of a necrotic tooth once the inflammatory stimulus is removed.

Figs. 6c_Clinical appearance of the canine gingiva one week after

cleaning and shaping of the lateral incisor.

Figs. 6d_Postoperative radiograph.

Figs. 7a_Fistula corresponding to the upper left central incisor.

Figs. 7b_Healing of the fistula one week later. The canal has been

cleaned, shaped, and irrigated with sodium hypochlorite, while the pulp chamber has been medicated with Cresatin and Cavit. In other words,

it has been treated as though the fistula did not exist. Its resolution

confirms that the diagnosis and therapy were correct and justifies

proceeding with three-dimensional filling of this root canal system.

Figs. 7c_Another view one year later.

Fig. 6c

Fig. 6d

Fig. 7a

Fig. 7b Fig. 7c

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Obviously, these fistulae must be distinguished from congenital fistulae of the neck, both lateral (arising from the second branchial cleft) and medial (arising from rests of the thyroglossal duct), which are lined by an epithelium. Such fistulae, however, have a different pathogenesis and obviously do not resolve spontaneously, but only after careful surgical exci-sion of the entire tract.27 The differential diagnosis includes the following:13,21

localized infections of the skin, such as pyo-derma, pimples, ingrown hairs, and obstructed sweat glands,traumatic or iatrogenic lesions,osteomyelitis,neoplasia,tuberculosis,ctinomycosis.

ConclusionEndodontic lesions with a fistulous tract should

always be welcome in our office. And this is true for many reasons:

The tooth responsible is necrotic, therefore the patient does not need any anesthesia, which means that while we make the access cavity, at the same time we perform the most important and the most reliable vitality test, the cavity test.The insertion of a gutta-percha cone in the fistulous tract will help in the diagnosis: the radiograph will immediately show the tooth responsible.The patient will never have a flare up. The re-crudescence after treatment or retreatment is nothing more than one little drop of pus coming out from the fistula, and the patient is not even aware of it.One week after cleaning and shaping of the root canal system, the fistula is gone, and this will confirm that we made the right diagnosis and

the right treatment.

The presence of a fistula, in conclusion, is not an in-dication for extraction, is not an indication for surgery, is not an indication for any specific medication: it is just an indication for a correct root canal treatment.

References:1. Baumgartner, J.C., Picket, A.B., Muller, J.T.: Microscopic examina-

tion of oral sinus tracts and their associated periapical lesions. J. Endod. 10:146, 1984.

2. Bella, G., Russo, S., Messina, G., Badalà, A.: Considerazioni sulle

Fig. 8a

Fig. 8b

Fig. 8c

Fig. 8d

Fig. 8e

Fig. 8a_Cutaneous fistula in the mental region.

Fig. 8e_Radiograph two years later confirms total resolution of the previous radiolucency.

Fig. 8d_Complete healing of the cutaneous fistula without any residual scarring after two years.

Fig. 8c_Postoperative radiograph. Three apicoectomies with amalgam retrofilling have been performed. Not the least attention has been paid to removal of all the granulation tissue or to curettage of the surrounding bone or apices, or to removal of the fistulous tract, or even to circular incision of the cutaneous orifice of the fistula.

Fig. 8b_Preoperative radiograph of the lower incisors. The patient elected surgical therapy for economical reasons. The left lateral incisor had already been subjected to a cavity test.

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Figs. 9a_Cutaneous fistula in the right submandibular region.

Figs. 9b_Preoperative radiograph of the ipsilateral lower first molar. The

tooth had been “opened” one month before and left open “to drain.” Note the small radiopacity at the center of the access cavity, due to a residuum

of the chamber roof left in place.

Figs. 9c_Clinical appearance of the access cavity: three openings have

been made in the roof of the pulp chamber! One, corresponding to the

distal canal, is shaped like a figure 8. The two round ones correspond

to the mesial canals: The pulp horns have been misdiagnosed for canal

orifices.

Figs. 9d_Postoperative radiograph. The tooth has been pretreated with a

cooper band.

Figs. 9e_Healing of the fistulous tract two years later. Note the

complete absence of any scarring.

fistole cutanee odontogene. Il dentista moderno, 10:2353, 1989.

3. Bence, R.: Trephination technique. J. Endod. 6:657, 1980.4. Bender, I.B., Seltzer, S.: The oral fistula: its diagnosis and treat-

ment. Oral Surg. 14:1367, 1961.5. Braun, R.J., Lehman, J.: A dermatologic lesion resulting from

a mandibular molar with periradicular pathosis. Oral Surg. 52:210, 1981.

6. Calvarano, G., De Paolis, F., Bernardini, G.: Fistole cutanee e salivari: soluzioni terapeutiche. Odontostomatologia e Implan-toprotesi, 1:82, 1991.

7. Cioffi, G.A., Terezhalmy, G.T., Parlette, H.L.: Cutaneous draining sinus tract: an odontogenic etiology. J. Am. Acad. Dermatol. 14:94, 1986.

8. Elliot, J.A., Holcomb, J.B.: Evaluation of a minimally traumatic alveolar trephination procedure to avoid pain. J. Endod. 14:405, 1988.

9. Feiglin, B.: Pain and fistulas can cross the midline. J. Endod. 11:132, 1985.

10. Galli, S., Galli, G.: Considerazioni anatomiche e cliniche su un caso di fistola odontogena. Odontostomatologia e Implanto-protesi, 6:50, 1989.

11. Grossman, L.I., Oliet, S., Del Rio, C.E.: Endodontic practice. 11th ed. Lea & Febiger, Philadelphia, 1988.

12. Harnisch, H.: Apicectomia. Scienza e Tecnica Dentistica. Edizioni Internazionali. Milano, 1981.

13. Heling, I., Rotstein, I.: A persistent oronasal sinus tract of endo-dontic origin. J. Endod., 15:132, 1989.

14. Ingle, J.I.: Endodontics, Lea & Febiger, Philadelphia, 1965, pp. 361–362,441.

15. Ingle, J.I.: Endodontics, 3rd ed. Lea & Febiger, Philadelphia, 1985.

16. Kaufman, A.Y.: An enigmatic sinus tract origin. Endod. Dent. Traumatol. 5:159, 1989.

17. Kelly, W.H., Ellinger, R.F.: Pulpal-periradicular pathosis causing sinus tract formation through the periodontal ligament of adjacent teeth. J. Endod. 14:251, 1988.

18. Lewin-Epstein, J., Taicher, S., Azaz, B.: Cutaneous sinus tract of dental origin. Arch. Dermatol. 114:1158, 1978.

19. Mcwalter, G.M., ALEXANDER, J.B., Del RIO, C.E., KNOTT, J.W.: Cutaneous sinus tracts of dental etiology. Oral Surg. 66:608, 1988.

20. Ordman, L.J., Gillman, T.: Studies in the healing of cutaneous wounds. II. The healing of epidermal, appendageal and dermal injuries inflicted by suture needles in the skin of pigs. Arch. Surg. 93:883, 1966.

21. Pagavino, G., Pace, R., Giachetti, L.: Le fistole cutanee odon-togene: diagnosi e tarapia, R.I.S., Anno LIX, 11/12:6, 1990.

22. Palattella, G., Mangani, F., Palattella, P., Palattella, D., Mauro, R.: Fistole cutanee da estrinsecazioni perimandibolari di parodon-titi apicali croniche. Dental Cadmos 2:57, 1987.

23. Peters, D.D.: Evaluation of prophilactic alveolar trephination to avoid pain. J. Endod. 6:518, 1980.

24. Sargenti, A.: Apical aeration made easy by a new instrument. J. Br. Endod. Soc. 6:49, 1972.

25. Schilder, H.: Endodontic therapy, in: Current therapy in Den-tistry. Goldman et Al. eds., vol. I, St. Louis, The C.V. Mosby Com-pany, 1964, pp. 84–102.

26. Seldon, H.S., Parris, L.: Management of endodontic emergencies. J. Dent. Child. 37:260, 1970.

27. Sicher, H.: Orban’s Oral Histology and Embriology, ed. 6, St. Louis, The C.V. Mosby Company, 1966, pp. 1–17.

28. Sommer, R.F., Ostrander, F.D., Crowley, M.C.: Clinical Endo-dontics, 3rd ed., W.B. Saunders Company, Philadelphia, 1966, p. 306.

29. Spear, K.L., Sheridan, P.J., Perry, H.O.: Sinus tracts to the chin and jaws of dental origin. J. Am. Acad. Dermatol. 8:486, 1983.

30. Strader, R.J., Seda, H.J.: Periapical abscess with intranasal fistula. Oral Srg. 32:881, 1971.

31. Weine, F.S.: Endodontic therapy, 2nd ed., The C.V. Mosby Com-pany, St. Louis, 1976.

32. Wolch, I.: A new approach to the basic principles of endodontics. Int. Dent. J. 25:179, 1975.

33. Zerman, N., Urbani, G., Menegazzi, G., Cavalleri, G.: Il trattamento di fistole cutanee da lesioni endodontiche. Il Dentista Moderno 7:1381, 1990.

Fig. 9a

Fig. 9b

Fig. 9c

Fig. 9d

Fig. 9e

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roots

Dr. Arnaldo CastellucciDr. Castellucci graduated in medicine at the University of Florence in 1973 and special-ized in dentistry at the same University in 1977. From 1978 to 1980 he attended continuing education courses in endodon-tics at Boston University School of Graduate dentistry with Prof.

Herbert Schilder. As well as running a practice limited to en-dodontics in Florence, Italy, Castellucci is past president of the Italian Endodontic Society, past president of the International Federation of Endodontic Associations, an active member of the European Society of Endodontology, an active member of the American Association of Endodontists, and a visiting professor of endodontics at the University of Florence Dental School. He is editor of The Italian Journal of Endodontics and of The Endodontic Informer, founder and president of The Warm Gutta Percha Study Club and The Micro-Endodontic Training Center, and he is international editor of Endo Tribune. An in-ternational lecturer, he is the author of the text “Endodontics,” which is now available in English.

This article is an excerpt from Dr. Arnaldo Castellucci’s textbook “Endodontics,” which is divided into three volumes and 35 chapters. Volumes 1 and 2 of this endodontic textbook are now available for the first time in English, completely revised with new chapters and many more color illustrations. Each volume comes complete with its own CD-ROM, which includes the complete text and illustrations in PDF files.

To order, contact Il Tridente S.R.L., Viale dei Mille 60, 50131 Firenze, Italy, Tel. +39 055 500 1312, Fax +39 055 500 0232, [email protected], or visit www.iltridente.it.

_About the author

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42 I

I research _ ceramics-based sealers

T he most ideal outcome of an endodon-tic treatment is hard tissue closure, which permanently separates the root canal content — the root filling — from the periapical tissues and prevents

chronic irritation and foreign body reactions by material components.7 Good instrumentation and cleaning of root canal combined with perfect hermetic closure of its apical third are decisive preconditions for achieving of full closure of root canal apical orifice with cementoid tissue. Closure of the root canal in this way ensures non-problematic and long-term function of the root in naturally wet environment surrounding it.

Today’s “golden” standard for endodontic treat-ment are warm condensation multi phase (gutta-percha — sealer ) techniques. These techniques, however, result in a friction fit, “cork-in-the-bottle” type sealing only. In the era of adhesive techniques in dentistry we have an endodontic standard, which lacks adhesion and chemical bond between root canal dentin walls and root canal filling materials. Visualiza-tion of sealer “puff” in periapical space on radiography does not give enough grounds to say that seemingly adequate root canal filling is an absolute guarantee of successful healing result.1 Shrinking of gutta-percha after the end of warm condensation and lack of adhe-sion of the root filling materials to dentinal root canal walls are factors creating enough predispositions for micro leakage. The known fact is that the hu-man body’s immune system can easily deal with this situation when titer of microorganisms is low. That capability of immune system is demonstrated by lack of periapical pathology and subjective complaints.

This equilibrium can easily be destroyed when due to different reasons human body’s reactivity is changed and existing balance is “pushed” toward appearance of pathologic periapical changes.

That is why the quest for endodontic sealers that adhesively and chemically bond to root canal walls continues. Clinical use of Bis-GMA based sealers in combination with polycaprolactone made cones is a promising step ahead,5,10 but in the area of the root canal apical third these materials are in constant contact with wet environment of periodontium and are subjected to action of enzyme systems there. Reported data about alkaline and enzyme hydrolysis of polycaprolactone and the shrinkage of Bis-GMA based sealer question the long-term stability of api-cal third hermetic seal achieved by these endodontic sealers.2,8,9

‘Endodontic grafting’Filling of the root canal apical third must be looked

upon separately from the filling of the rest of the canal having under consideration the active and constant metabolic processes occurring in the periapical area. Special attention must be paid to the interface formed between dentinal root canal walls, gutta-percha and sealer on one side and periodontium and body fluids on the other side. Long-term hermetic sealing of apical third achieved in constantly wet environment is an ob-ligatory condition to ensure lack of microbial growth. Another extremely important factor promoting hard tissue closure of the canal is presence of osseocon-ductivity as sealer’s feature. Perfect and lasting in wet environment hermetic seal of apical third combined with osseoconductivity of endodontic sealer ensure

roots 1_2009

Ceramics-based sealers as new alternative to currently used endodontic sealersAuthors_ Deyan Kossev & Valeri Stefanov, Bulgaria

Fig. 1_Polarisation microscopy. Horizontal cut. Dark green — dentin,

white — bioceramic-based sealer iRoot SP, orange — gutta-percha

cone.

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research _ ceramics-based sealers I

roots 1_2009

conditions for hard tissue closure of root canal apical orifice in time. Filling of the root canal with ceramic sealer, which due to its osseoconductivity action promotes the physiological closure of the canal by cementoid hard tissue, can be called “endodontic grafting.” Such endodontic grafting can ensure the lasting root’s health while it constantly remains in contact with body fluids.

The use of bioceramic-based sealers with their fea-tures — osseoconductivity, hydrophylity, adhesiveness and chemical bonding to root canal dentinal walls — appears to be an effective approach to eliminate (Fig. 1) on long term, the microspace, otherwise remaining between the root canal walls and the materials filling the root canal. Such microspace is a potential place for possible microbial growth, because of microleakage observed with other kind of sealers.

Sealers for ‘endodontic grafting’Endodontic sealers that set hard and are stable in

constantly wet environment are :a. Recently created calcium — silicate — phos-

phate-based bioceramic nano-compositions — Bio-Aggregate, iRoot SP and iRoot BP (IBC, Canada).

b. MTA-based products — “MTA — Angelus” (AN-GELUS, Brazil), ProRoot (Dentsply, USA), Aureoseal (OGNA, Italy).

The common feature of all these products is that when used to fill the apical third of the root canal, they guarantee adhesive hermetic seal.4 They do not get destroyed during their hardening and afterward while being constantly in contact with the wet periapical environment. They are very stable in time. Ceramic-based sealers ensure much better apical seal than IRM, amalgam or Super EBA materials, and this excellent seal is combined with excellent biocompatibility and significant stimulation of periodontal regeneration.5,6 Until recently the application of all these materials, except for iRoot SP and iRoot BP, required significant widening of the root canal apical third — up to #60–70 — and use of specially developed instruments to carry the materials to apical third of the canal. These purely technological limitations were reducing ceramic-based materials use as regular antegrade root canal filling materials.

The first author has developed an innovative method for filling of apical third of the root canal with MTA- and bioceramic-based sealers he has called the “capillary condensation” technique. This new tech-nique does not require enlargement of the canal’s apical third more than # 35-40 / 04. Apical third of canal space is widened based on its original size and shape only.

Method for ‘capillary condensation’ of ceramics-based endodontic sealers to fill the root canal

Method comprises of several stages:

I. Preparation of “coronal reservoir” from which ceramic sealer to be condensed aside to canal walls and toward and into canal’s apical third so that to seal the canal’s apical orifice.

Using RGG or GG drills, the coronal third of the root canal is conically widened to form a “coronal reservoir,” which is subsequently to be filled with MTA, BioAggregate, iRoot SP or iRoot BP material.

From this point on, there are two different ap-proaches:

A. “Coronal reservoir” is filled directly with ready-to-use material packed into syringes (iRoot SP or iRoot BP). Mini applicators included in the package are used for direct filling of reservoir with factory premixed material.

B. Powder-like ceramic material (MTA or biocer-amic-based BioAggregate) is mixed with distilled wa-ter to form a paste with suitable viscosity to allow car-rying it into the “reservoir” by plastic carrier designed by the author. Micro applicator handle, with “fluffy” head cut, may be used instead, too. (Fig. 2)

The dentist can fold the plastic carrier as needed to make it suitable to easily get inside the “coronal reservoir.” Small portions of “ex tempore” mixed sealer are carried into the “reservoir” until it gets full. It is im-portant to work in constantly slightly wet root canal. Before putting next small portion of MTA or BioAggre-gate sealer into reservoir, the dentist visually controls the moisture of the sealer mass. If necessary the tip of the plastic carrier is wetted with distilled water and put inside the reservoir to increase the humidity of the sealer mass inside. Thus the risk of drying of material at the bottom of the reservoir is avoided and ceramic sealer is prepared for condensation further inside the root canal.

II. “Capillary condensation” of the sealer to fill the root canal

This stage is valid for both (A and B) types of ce-ramic sealers. Condensation of the sealer is made with “condensor” — an instrument designed by the authors (Fig. 3). The basic rule is correctly chosen instrument to get freely inside into root canal within 1 mm less than canal’s measured working length (WL). In case of straight canals the number (#) of the instrument must be one number (#) less than MAF. In slightly or severely curved canals the number (#) of the used instrument must be two to three numbers (#) less than MAF. It is preferable to use NiTi made instruments, especially in curved canals.

By pushing the condensor slowly in and then get-ting it out, without taking it totally out of “coronal reservoir,” the sealer is condensed inside the canal, aside to canal’s walls and at the same time toward its apical orifice, down to previously defined depth of 1 mm less than WL. Condensation must be done slowly and with maximum possible amplitude of the “push-in” and “take-out” movements (Fig. 4).

Fig. 2_Plastic applicator inside simulated root canal “coronal reservoir.”

Fig. 3_Condensor inside simulated root canal down to 1 mm less than WL.

Fig. 4_Condensor in the moment of “take-out” movement start (compare to Fig. 3).

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44 I roots 1_2009


When condensing the powder-like ceramic seal-ers (MTA-based or BioAggregate) that are mixed “ex tempore” before use, there should not be a tactile feeling of “tightening” of the instrument inside the canal during condensation. If such a feeling appears, the dentist must take the condensor totally out of the canal and must wet the tip of the instrument with wa-ter before inserting it inside the canal again. The total time for the sealer’s condensation is approximately 10–15 seconds. Between 12 and 15 “push-in/take out” movements are needed to achieve a good filling of the canal’s apical third and to ensure good adhesion of the sealer to canal’s walls, too. Ten seconds after the start of condensation (approximately 10 “push-in” move-ments) the dentist must take the instrument out of canal. There should not be hardened aggregates on the instrument’s surface, but only liquid white solu-tion. Then one must look at the bottom of the “coronal reservoir.” If there is a “black hole,” this means more water must be added to the sealer inside the reservoir. The tip of plastic carrier is wetted with water and is put inside the reservoir. This is to be immediately followed by adding one more small portion of the mixed sealer into the reservoir. Important note: Do not add water when using bioceramic-based iRoot SP and iRoot BP sealers! Only the additional portion of sealer must be added when using iRoot SP or iRoot BP! These two sealers are supplied premixed and “ready to use” and do not need additional water, they have already been factory mixed to optimal viscosity to fill the canal properly.

III. Insertion of gutta-percha conesAt the moment of choosing the correct size con-

densor, the dentist must also choose the same size gutta-percha master cone. Inserting of the gutta-percha cone inside the canal will serve three functions simultaneously.

A. It will finish the condensation of the sealer inside the root canal and will make sealer layer along the canal’s length even. It will eliminate any air still entrapped inside the canal, too.

B. It will create a pliable space inside the canal with which to accommodate the stress created by expan-sion of the ceramic sealers during their hardening. Bioceramic-based sealers BioAggregate, iRoot SP and iRoot BP have significant expansion of 0.20 percent.

C. By inserting the gutta-percha cones the pos-sibility for re-entering the canal is maintained, and easier preparation of calibrated “bed,” for cementing a fiberglass post inside, is ensured.

The master gutta-percha cone is inserted slowly with “push-in” and “take-out” motions down to 1 mm less than WL. Additional smaller diameter gutta-percha cones may be added, if necessary. The ends of gutta-percha cones extending out of the root canal are cut and cones are condensed with round head metal instrument. During gutta-percha condensa-tion excessive water and excessive sealer remnants are also pushed outside and are wiped out with small cotton pellet. A temporary filling is placed in the tooth cavity. After the ceramic sealer is hardened, preferably 24 hours after canals are filled, the final restoration is made.

Clinical application of ‘capillary condensation’ technique 1. Filling with MTA

Fig. 5a_Before (Rx made on Nov. 24, 2006) Fig 5b_After (Rx made on March 30, 2007) Fig. 6a_Before (Rx made on June 8, 2006) Fig. 6b_After (Rx made on June 25, 2006)

Fig. 5a Fig. 6aFig. 5b Fig. 6b

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I 45roots 1_2009


Features of ceramic-based endodontic sealers

1. Ceramic-based sealers are highly hydrophilic and have low contact angle. These features allow them to spread easily over the dentin walls of the root canal and to get inside and fill the lateral micro canals, too. Thus necessity to instrument the canals with 06 or higher taper becomes no longer needed. Tooth tissues are preserved, and risk of root fractures is reduced.

Very well-filled lateral micro canals can be seen on experimental samples. Filling is done with iRoot SP (Figs. 12, 13).

2. During setting hard ceramic-based sealers expand. Expansion of BioAggregate and iRoot SP and iRoot BP is significant — 0.20 percent. These new bioceramic sealers also form chemical bond with the canal’s dentin walls. That is why no space is left be-tween the sealer and dentin walls. This is well demon-strated by light polimerization microscopy and much better demonstrated by large magnification scanning

Fig. 7a_Before. Fig.7b_After — three mesial canals filled.

Fig. 11a_Before.

Fig. 8b_After — see the difference in radiopacity of gutta-percha cones and bioceramic-based BioAggregate sealer (arrows).

Fig. 12_Small micro canal filled with iRoot SP (arrow). Horizontal cut. Polarisation microscopy. Black — root dentin, white — iRoot SP sealer, orange — gutta-percha cone.

Fig. 13_Lateral micro canal with an additional branch perfectly filled by iRoot SP sealer (arrows). Horizontal cut. Polarisation microscopy. Black — root dentin, white — iRoot SP inside micro canal.

2. Filling of root canals with BioAggregate.

3. Filling of root canals with iRoot SP. Note excellent radiopacity of this bioceramic sealer.

Fig. 9a

Fig. 10a

Fig. 11a

Fig. 7a

Fig. 8a

Fig. 9b

Fig. 10b

Fig. 11b

Fig. 7b

Fig. 8b

Fig. 12

Fig. 13

Fig. 11b_One month after the filling.

Fig. 8a_Before.

Fig. 9a_Before. Fig. 9b_After.

Fig. 10a_Before. Fig. 10b_Three weeks after filling.

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Fig. 16a_Right after filling (Rx made on Dec. 19, 2008).

Fig. 16b_Note significant bone recovery only 20 days after filling (Rx

made on Jan. 9, 2009).

Fig. 17a_Large diffuse exacerbated periapical bone lesion. After

instrumentation and cleaning root canals were filled with CaOH for three days with no improvement. After third

day CaOH was removed and canals were cleaned and filled directly with

iRootSP. Pain was gone in several hours after the filling with iRootSP was done and palpable intraorally

subperiosteal swelling was resolved totally within 24 hours (Rx made on

Dec. 16, 2008).

Fig. 17b_Only three weeks later, a significant bone lesion improvement

can be seen, too (Rx made on Jan. 9, 2009).

Fig. 18a_Periapical bone lesions around roots of lower incisors (Rx

made on Jan. 7, 2008).

Fig. 18b_Significant bone recovery is seen just about one month after

canals were instrumented, cleaned and filled with BioAggregate. Lateral

incisor was instrumented, cleaned and filled with iRootSP due to an acute pulpitis (iR). In fact second

radiography was made to evaluate the filling with iRootSP, but revealed

nice bone healing around central incisors for such a short period of

time, too (Rx made on Feb. 11, 2008).

electron microscopy (Figs. 14, 15).

3. Bioceramic-based sealers are capable of achiev-ing fast alleviation of the pain syndrome in cases of acute periapical inflammation. After appropriate instrumentation and cleaning of the root canal, fol-lowed by immediate filling with iRoot SP, pain rapidly diminishes and most often is totally gone within a period of 50 minutes to few hours.

4. In cases of MTA-based materials extrusion outside the root canal is associated with severe pain felt by the patient. When bioceramic-based sealers BioAggregate or iRoot SP are extruded, the pain is

relatively small or totally absent. Such lack of pain may be explained with the characteristics of these new materials. During hardening they “produce” hydroxylapatite and after the end of hardening proc-ess they exhibit the same features as non-resorbable hydroxylapatite-based bioceramics used for bone replacement in oral surgery. Due to the hydroxyla-patite formed, they are also osseoconductive (Figs. 16–18).

5. MTA-based materials and BioAggregate have quite poor radiopacity, different from bioceramic based iRoot SP and iRoot BP sealers. This difference is easily demonstrated by the following experiment. Root canals of extracted teeth have been instru-mented with TF files (SybronEndo) and cleaned. Two of the canals were filled with iRoot SP, and the other two with BioAggregate, respectively (Fig. 19). Note the excellent radiopacity of iRoot SP (left) compared to BioAggregate (right).

When roots’ apical thirds of same tooth, which does not contain gutta-percha, were cut and investi-gated under polarization microscopy, no difference in quality of achieved canal seal have been found (Figs. 20, 21).

Based on the above findings, it is preferable that bioceramic-based iRoot SP sealer be used for “endo-dontic grafting” (i.e., filling of root canals) because of its excellent radiopacity. It is not possible to verify the quality of root canal filling achieved with MTA-based materials or BioAggregate using radiographies only, due to poor radiopacity of these materials.

DiscussionCantatore3 define ideal conditions for endodontic

sealers as follows:1. Adequate consistency and adhesion to dentinal

walls

Fig. 14 Fig. 15

Fig. 16a

Fig. 17a

Fig. 16b

Fig. 17b

Fig. 19

Fig. 14_Polarisation microscopy. Horisontal cut. S — Bioceramic

sealer iRoot SP. D — Root dentin.

Fig. 15_SEM x 5000. iR — bioceramic sealer iRoot SP.

D-dentinal tubules of root canal wall. Points bar is equal to 10 microns. Distance between dots is equal to 1 micron only. White arrow shows the interface between sealer and

dentin without presence of any voids because of chemical bond between

dentin and sealer.

Fig. 18a Fig. 18b

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I 47roots 1_2009

2. Adequate working time.3. Capacity to produce a hermetic seal.4. Easy handling.5. Radiopacity.6. Expansion at the time of set.7. Antibacterial action.8. Biocompatibility.9. Insolubillity in tissue fluids.10. To allow retreatment of the canal.11. Do not discolor dental tissues.12. No antigenic action.13. No mutagenic action.Sealers routinely used in endodontics and based

on epoxy resin, calcium hydroxide, glass ionomer, zinc oxide — eugenol, formalin-resorcine pastes, polyc-aprolactone and Bis-GMA ± do not meet one or more of above listed requirements.

MTA-based materials (MTA-Angelush, ProRoot — Dentsply, Aureoseal — OGNA) exhibit good adhesion to dentinal walls of root canal, but until recently they required very big enlargement of canal’s apical third to be easily applied. With the method for “capillary condensation” developed by the first author for filling of root canals, these materials became easy to apply into the canal space.

Bioceramic-based materials having nano-sized particles (BioAggregate, iRoot SP, iRoot Bp) achieve excellent adhesion to the canal’s dentinal walls and, more importantly, form a chemical bond with dentin. Structure of these materials during their mixing with water allows a very good consistency to be achieved (BioAggregate) or optimal consistency is already guaranteed by manufacturer by offering premixed “ready-to-use” products (iRoot SP, iRoot BP). All ce-ramic-based sealers are hardening slowly. This feature gives the dentist the possibility to do corrections of the filling, if control radiography has revealed any prob-lems. Due to their hydrophilicity and low contact an-gle, all ceramic-based sealers achieve extremely good hermetic seal. All MTA- and bioceramic-based sealers are quite easy to use when the dentist has mastered the “capillary condensation” technique for filling of root canals. MTA-based materials and BioAggregate have poor radiopacity, differently from iRoot SP and iRoot BP. All ceramic-based sealers expand during the time of set. They exhibit potent antimicrobial action, too. All ceramic sealers are biocompatible and insolu-ble in tissue fluids. They have not demonstrated until now any antigenic or mutagenic action. When used in combination with gutta-percha cones, re-entering of the canal space is possible and a calibrated “bed” may be drilled to accommodate a fiberglass post into the canal.

ConclusionsPotent antibacterial activity, absolute biocompat-

ibility, osseoconductivity, ability to achieve excellent hermetic seal in constantly wet environment, for-

mation of chemical bond with dentin, insolubility in tissue fluids, expansion during time of set, very good radiopacity, easy handling are the features that make bioceramic-based sealers an up-to-date alternative to current “golden” standard of multi-phase (gutta-percha — epoxy sealer) warm techniques.

Thanks to its very good features, iRoot SP is cur-rently probably the best product to be used with “capillary condensation” technique for “endodontic grafting” of apical third and for hermetic sealing of complex root canals space.

AknowledgmentsScanning electron microscopy has been kindly of-

fered for use in this article by IBC — Canada. It is the property of INNOVATIVE BIOCERAMIX.

The authors would like to express their thankful-ness to Marlena Tchimpilska, Medical Library, Medical University of Pleven, for help with literature search; Vesselin Nedelcev for preparation of polarisation microscopy samples; and to Elena Stoyanova, dental assistant.

Fig. 20 Fig. 21

Fig. 20_Canal filled with iRoot SP. Fig. 21_Canal filled with BioAggregate.

_About the authors roots

Dr. Deyan Kossev Dr. Deyan Kossev graduated from the Dental Faculty of Medical University of Plovdiv in 1991. Between 1991 and 1995 he practiced as a GP, and between 1995 and 2001 as a staff member of Oral Surgery Department of Municipal Dental Clinic, Kazanlik. Since 2002 he has been working exclu-sively in private practice, specializing in endodontics, restorative dentistry and implantology. Kossev may be contacted at [email protected].

Dr. Valeri StefanovDr. Valeri Stefanov graduated from the Dental Faculty of Medical Academy of Sofia in 1982. He practiced as a GP from 1982 to 1986 at the Dentistry Department of Municipal Hospital of Levski. Between 1986 and 1992 he practiced as an oral surgeon at OMS Department of Municipal Hospital of Pleven. Since 1993 he has been exclusively in private practice, specializing in oral surgery, implantology, endodontics and restorative dentistry. In 1990 Stefanov was awarded the Leibinger Prize for extraordinary contribution to the specialty of OMFS by the European Association of Cranio-Maxillo-Facial Surgery. He is an honorary member and diplomate of the German Society for Implant Dentistry (DGZI). He has been a member of Editorial Board of IJOMFS. He is founder and former president of the Bulgarian Society of Oral Implantology and Biomaterials. He lectures nationally and internationally. Stefanov may be contacted at [email protected].

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References:1. Bergenholz, G. et al. Controversies in Endodontics / G. Ber-

genholz, L. Spangberg. // Crit. Rev. Oral Biol. Med, 15, 2004, 2 : 99–114.

2. Bodrumlu, E. et al. Apical leakage of Resilon obturation material / E. Bodrumlu, U. Tunga. // J. Contemp. Dent. Pract., 7, 2006, 4 : 45–52.

3. Cantatore, G. Obturation canalaire et preservation radiculaire / G. Cantatore. // Realites Cliniques, 15, 2004, 1 : 33–53.

4. Gohring, K.S. Indications for use of MTA, a review. Part 1: Chemi-cal, physical and biological properties of MTA / K.S. Gohring, B. Lehnert, M. Zehnder. // Schweiz. Monatsschr. Zahnmed., 114, 2004, 2 :143–53.

5. Maltezos, C. et al. Comparison of the sealing of Resilon, Pro Root MTA, and Super-EBA as root-end filling materials: a bacterial leakage study / C. Maltezos, G.N. Glickman, P. Ezzo, J. He. // J. Endod., 32, 2006, 4 :324–327.

6. Rafter, M. Apexification: a review / Mary Rafter // Dental Trau-

matology, 21, 2005, 1 : 1–8. 7. Ricucci D. et al. Apical limit of root canal instrumentation and

obturation : Part 2. A histological Study / D. Ricucci, K. Langeland. // Int. Endod. Journal, 31, 1998: 394–409.

8. Tay, F.R. et al. Suseptibility of a polycaprolactone based root ca-nal filling material to degradation. I. Alkaline Hydrolysis / F.R. Tay, D.H. Pashley, M.C. Williams, R. Raina, R.J. Loushine, R.N. Weller, W.F. Kimbrough, N.M. King. // J. Endod., 31, 2005 : 593–598.

9. Tay, F.R. et al. Susceptibility of a polycaprolactone-based root canal filling material to degradation. II. Gravimetric evaluation of enzymatic hydrolysis / F.R. Tay, D.H. Pashley, C.K. Yiu, J.Y. Yau, M. Yiu-fai, R.J. Loushine, R.N. Weller, W.F. Kimbrough, N.M. King. // J. Endod., 31, 2005, 10 : 737–41.

10. Verissimo, D.M. et al. Comparison of Apical Leakage between Canals Filled with Gutta-Percha/AH-Plus and the Resilon/Epiphany System, When Submitted to Two Filling Techniques / D.M. Verissimo, M. Sampaio do Vale, A.J. Monteiro. // J. Endod., 33, 2007, 3 :291–294.

48 I roots 1_2009

I industry report_ VDW

A n ultrasonic device in endodontics — why is it necessary? It is a fact that today’s endo-dontists can no longer think of endodontic

treatments without ultrasound, not because they want high standard equipment, but because they know about the essential advantages the ultrasonic technique provides for their endodontic treatments. The increasing demand comes mostly from practices that are either interested or specializing in endodon-tics. For this reason VDW, the expert in endodontics, has developed an ultrasonic device especially for root canal treatment: the VDW.ULTRA®.

The main function of this device surely is the activation of irrigation: vibrations create air bubbles

in the irrigation solution, they implode immediately and remove tissue and bio film. They reach into dentin tubules and lateral canals and reduce significantly the infection risk. As mere mechanical preparation reaches only about 70 percent of these areas, inten-sive irrigation is crucial for eliminating bacteria. A new feature is the passive ultrasonic irrigation with special instruments avoiding unwanted filing in the irrigation phase.

Additional functions, such as fine-preparation of the access cavity, retreatment, as well as removal of metal posts and fractured instruments, are available. The handy device provides high comfort treatments. Thanks to the patented “auto-balance-system” en-suring reliable automatic regulation, the VDW.ULTRA is able to deliver a constant and efficient performance for every application. The piezo-electric handpiece weighs only 50g and can be sterilized in the autoclave. Also classic periodontal and scaling applications can be carried out efficiently.

VDW provides a high-quality tailor-made tip assortment for use in endodontics: irrigation files for thorough ultrasonic cleaning and the removal of bio film, diamond-coated tips for efficient fine-preparation of the access cavity, fine tips made of the novel (innovative) titanium-niobium alloy for delicate retreatments, as well as a robust tip to remove metal posts with high intensity.

For more information, visit VDW online at www.vdw-dental.com.

An ultrasonic device with focus on endodontics

The VDW.ULTRA ultrasonic device enhances endodontic treatment.

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I 49

about the publisher _ submissions I

roots 1_2009

submissions:formatting requirements

_Please note that all the textual elements of your submission:

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In addition, images (tables, charts, photo-graphs, etc.) must not be embedded into the Word document. All images must be submit-ted separately, and details about how to do this appear below.

Text lengthArticle lengths can vary greatly—from a mere 1,500 to 5,500 words—depending on the subject matter. Our approach is that if you need more or less words to do the topic justice then please make the article as long or as short as necessary.

We can run an extra long article in multiple parts, but this is usually discussing a subject matter where each part can stand alone because it contains so much information. In addition, we do run multi-part series on various topics.

In short, we do not want to limit you in terms of article length, so please use the word count above as a general guideline and if you have specific questions, please do not hesitate to contact us.

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ments but send us the largest file sizes available. (The larger the starting image is in terms of bytes, the more leeway the designer has in terms of resizing the image to fill up more space should there be room available).

Also, please remember that you should not embed the images into the body of the text document you submit. Images must be submitted separately from the textual submission.

You may submit images through a zipped file via E-mail, unzipped individual files via E-mail, or post a CD containing your images directly to us (please contact us for the mailing address as this will depend upon where in the world you will be mailing them from).

Please do not forget to send us a head shot photo of yourself that also fits the parameters above so that it can be printed along with your article.

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Questions?Please contact us for our Author Kit, or if you have other questions:

Managing EditorFred [email protected]

RO0109_1-52.indd 49 3/5/09 11:58:13 AM

50 I

I about the publisher _ imprint

roots 1_2009

Publisher Torsten R. Oemus [email protected]

President Peter Witteczek [email protected]

Chief Operating Officer Eric Seid [email protected]

Group Editor Robin Goodman [email protected]

Editor in Chief Karl Behr [email protected]

Managing Editor Fred Michmershuizen [email protected]

Art Director Yodit Tesfaye Walker [email protected]

Marketing Manager Anna Wlodarczyk-Kataoka [email protected]

International Administration President/CEO Torsten R. Oemus [email protected]

Executive Vice President Finance Dan Wunderlich [email protected]

International Offices

Europe Dental Tribune International GmbH Contact: Daniela Zierke Holbeinstr. 29 04229 Leipzig, Germany Phone: +49-341-48474-302 Fax: +49-341-48474-173 www.dti-publishing.com

Asia Pacific Dental Tribune Asia Pacific Ltd. Contact: Tony Lo Room 1602, 108 Java Road North Point, Hong Kong Phone: +852-3118 7508 Fax: +852-3118 7509 www.dti-publishing.com

The Americas Dental Tribune America, LLC Contact: Anna Wlodarczyk 213 West 35th Street, Suite 801New York, NY 10001Tel.: +1 (212) 244-7181 Fax: +1 (212) 244-7185 www.dti-publishing.com

Editorial Board Members Fernando Goldberg, Argentina Markus Haapasalo, Canada Ken Serota, Canada Clemens Bargholz, Germany Michael Baumann, Germany Benjamin Briseno, Germany Asgeir Sigurdsson, Iceland Adam Stabholz, Israel Heike Steffen, Germany Gary Cheung, Hong Kong Unni Endal, Norway Roman Borczyk, Poland Bartosz Cerkaski, Poland Esteban Brau, Spain José Pumarola, Spain Kishor Gulabivala, United Kingdom William P. Saunders, United Kingdom Fred Barnett, U.S.A. L. Stephan Buchanan, U.S.A. Jo Dovgan, U.S.A. Vladimir Gorokhovsky, U.S.A. James Gutmann, U.S.A. Ben Johnson, U.S.A. Kenneth Koch, U.S.A. Sergio Kuttler, U.S.A. John Nusstein, U.S.A. Ove Peters, U.S.A. Jorge Vera, Mexico

roots_Copyright Regulations _the international magazine of endodontics is published by Dental Tribune America LLC and will appear in 2009 with one issue every quarter. The magazine and all articles and illustrations therein are protected by copyright. Any utilization without the prior consent of editor and publisher is inadmissible and liable to prosecution. This applies in particular to duplicate copies, translations, microfilms, and storage and processing in electronic systems.

Reproductions, including extracts, may only be made with the permission of the publisher. Given no statement to the contrary, any submissions to the editorial department are understood to be in agreement with a full or partial publishing of said submission. The editorial department reserves the right to check all submitted articles for formal errors and factual authority, and to make amendments if necessary. No responsibility shall be taken for unsolicited books and manuscripts. Articles bearing symbols other than that of the editorial department, or which are distinguished by the name of the author, represent the opinion of the afore-mentioned, and do not have to comply with the views of Dental Tribune America LLC. Responsibility for such articles shall be borne by the author. Responsibility for advertisements and other specially labeled items shall not be borne by the editorial department. Likewise, no responsibility shall be assumed for information published about associations, companies and commercial markets. All cases of consequential liability arising from inaccurate or faulty representation are excluded. General terms and conditions apply, legal venue is New York, NY, U.S.A.

rootsthe international magazine of endodontics

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