Category Archives: Materials

How Does Your Endodontist Do it?

If you are interested in an endodontic refresher lecture, come and join me next Thursday at the Pacific Dental Conference (PDC 2019).  Two and a half hours lecture filled with pictures and videos demonstrating the initial endodontic treatment.

Dr. Ektefaie PDC 2019


Walking Bleach since 1938

Tooth discolouration as a result of intrapulpal hemorrhage (i.e. traumatic dental injuries, pulp necrosis, pulp tissue remnants after endodontic therapy, internal resorption, etc.) can be effectively and safely corrected with walking bleach (internal bleaching) technique.  This technique is a conservative alternative to a more invasive esthetic treatment such as placement of crowns or veneers.

internal bleachingwalking bleach

 

Requirements for the proper technique:

  1. recording the initial shade with a shade guide
  2. performing adequate endodontic treatment under rubber dam isolation
  3. removing all obturation/restorative material to the level below CEJ conservatively
  4. placing a barrier (GIC, composite, IRM, etc.) over the obturation material to the level 1mm incisal to external probing of the gingival attachment
  5. packing sodium perborate (mixed with water or anesthetic solution) in the chamber
  6. sealing the access cavity with GIC or composite
  7. following up in 1 week to determine the final result (the bleaching procedure can be repeated 3-4 times)
  8. removing the bleaching agent and restoring the access cavity permanently
  9. recording the final shade

Office website: vanendo ,  FaceBook page: @endospecialists


Not Every Hole is a Canal!

Sometimes when we try locating canals during access preparation stage, we may accidentally exit the pulp chamber in the wrong spot and create perforations.  Perforations or accidental communications need to be repaired as soon as possible in order to achieve the best possible prognosis.  The choice of repair material depends on the location and the size of perforation. MTA is still one of the best materials that can be used to seal the pulp floor perforations as long as it is not communicating with the sulcus.

To Prevent Perforations:
1. The pulp chamber floor is always at or slightly below the level of CEJ and the canals are located at the periphery of the pulp chamber floor.  Any attempt to locate canals farther apically may result in perforation.
2. The chamber floor colour is always greyish. If the colour during locating canals is turning dentin-colour, that would be the best time to stop and reorient ourselves.
3. Always probe around the CEJ to gain a better appreciation the outline of the root trunk, as the chamber floor is at the center and concentric to the CEJ outline.
4. When in doubt, stop and take an X-ray to confirm that treatment is progressing in the right direction.

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To Treat Perforations:
1. If facing significant difficulty with locating canals, the procedure should be stopped, the tooth should be medicated with CaOH, and patient should be referred out for proper care.  More digging may result in multiple perforation sites, further weakening of the tooth structure and enlargement of the existing perforation site, which ultimately results in an unfavorable outcome.
2. If canals are already located, ignore the perforation site, complete the root canal treatment and repair the perforation site with MTA.  Attempting to repair the site before obturating the canals may result in the repair material occluding the shaped and cleaned canals.
3. When dealing with established infection in the canal system which benefits from the utilization of short term CaOH medicament, the perforation site can be repaired and sealed before final obturation. In this case, the other canals need to be protected by paper points while the site is being repaired (the above case).


MTA…saving open apices one tooth at a time!

Providing root canal treatment can be challenging in teeth with incomplete root formation. The apex is large and open, the canals walls are thin and fragile, and this makes disinfection and obturation hard to do. Before the advent of MTA, calcium hydroxide was used in teeth with open apices over a long period of time, anywhere from 6 months to 24 months, to induce a calcified barrier over the open root apex. It was and still is a very effective treatment modality, especially with a good coronal seal. Calcium hydroxide is also still very important for treating resorptions, and aiding in disinfection of root canals! However, we now know that keeping calcium hydroxide for many months in a weak root can possibly further weaken dentin, and using MTA can shorten the treatment time to one or two visits. The placement of a “plug”, usually a 3-5 mm plug of MTA at the end of an open apex root canal, provides an “instant” apical barrier against which we can place gutta percha and sealer into the remainder of the root canal.

In this particular case, the patient was going to have new crowns placed very soon. I removed the old gutta percha quite easily with a #35 Hedstroem file, and you can see all sorts of things growing on it in the photo! Because the tooth was purulent and “weepy”, the root was allowed to drain for a few minutes, and then irrigated with 5.25% sodium hypohlorite using a closed-end side-vented irrigation needle after the working length was determined. I packed calcium hydroxide into the root for about 2 weeks in this tooth before doing the one-visit MTA apexification procedure due to the continued exudate and to aid in disinfection.

On the day of MTA apexification, this is what I did:

1. Rubber dam of course, irrigate calcium hydroxide out with full strength sodium hypochlorite, circumferential filing, and final irrigation procedures

2. Dry the canal. At this point, if the canal continued to well up with exudate, I would consider remedicating with calcium hydroxide.

3. Place an apical matrix of collagen (for example, Collacote) if you feel you might need an apical matrix to “contain” your MTA plug; this serves as a support against which you can gently condense the MTA.

4. Using a small carrier, such as a Dovgan carrier or MAP system (like a mini amalgam carrier), place MTA as far apically as possible, and then carry/tamp down gently using a pre-measured plugger or a moist paper point (a big one, like extra coarse!).

5. I usually take a radiograph here after the first 1 mm increment, to make sure that I have placed it flush with the root apex. Once this is confirmed, you can place a 3-5 mm plug.

6. The rest of the canal can be obturated with sealer and thermoplasticised GP, and the tooth definitely restored. Many also advocate placing a damp cotton pellet and temporary filling before definitively restoring the access to ensure the MTA has set. In the x-ray, I have placed 5 mm of MTA, sealer and GP on top, a 2 mm layer of glass inonomer, and then a bonded restoration (double seal). The dentist has completed the case with beautiful crowns.

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Irrigation…how low do you dare to go?

Irrigating the canals…probably the easiest part of providing root canal treatment, yes?

I think I graduated from dental school years and years ago with a deeply instilled fear of perforation, a reluctance to tackle calcified teeth, and anxiety whenever I waited for my obturation film to emerge from the processor. Irrigating the root canal was the breeziest part of treatment, to my memory. I placed an irrigating tip into the canal, made sure it didn’t bind in any place, it was probably hanging around the coronal or mid-root part of the canal, and I pressed the plunger a few times. Presto! Irrigation done. Right. Right?

Reading up on the irrigation literature these past few years has changed my thinking about the importance of irrigation, and it is a procedure that I spend a lot of time on now, probably equalling instrumentation! Many advocate viewing shaping of the canal with rotary instruments as a means to allow irrigants to effectively reach the most apical portion of the root canal. Many would be surprised to see that if our irrigation needle tips are not placed in the apical third of the root canal, we may not be achieving effective irrigation. The easiest way to show this is through a little home made video here, which shows me irrigating in a plastic canal, with a 30 gauge needle, using a fair amount of pressure, equal to about 5 ml/min. The needle tip is held about 3 or 4 millimeters from the “end” of the root canal. Notice how the exchange of irrigant only extends a small distance beyond the end of the needle tip: 

Based on some of the literature to date, here are a few suggestions for achieving effective irrigation using a conventional irrigation method:

1. Use a flexible, small gauge irrigation needle, for example, a 30 gauge needle or smaller, that is designed with a closed-end and side-vent (for patient safety). I find that it is quite difficult to use an irrigation needle bigger than a 30 gauge needle, unless the root canal is very large.

2. Prepare the root canal to an adequate apical size and taper such that a small gauge irrigation needle can be placed within 1-2 mm of the working length, or at least in the apical third.

3. Use very gentle finger pressure! A high irrigation flow rate (e.g. high finger pressure) is not required; recent research shows that high pressure/high flow rates does not correlate to “better cleaning”.

4. Activate your irrigants! Use of a sonic or passive ultrasonic tool, such as the EndoActivator by Tulsa, or the Irrisafe file by Clinical Research Dental can make your irrigation more effective. There are many options for agitating your irrigants, and I try to “energize” each irrigant that I use for at least 45-60 seconds per canal, per irrigant, after the majority of the cleaning and shaping has been done.

If you like reading journal articles, here is my recent paper on the “theoretical measured pressure” that the periodontal ligament might feel when we are irrigating root canals. We also have a review paper on irrigation of the apical third in the journal Endodontic Topics, have a read. Send us a message if you can’t find it. Park Shen Haapasalo 2013 irrigation JOE


How do you “seal” the deal?

After we’ve spent so much time doing great endodontic treatment – with rubber dam isolation, perhaps gingerly applying OraSeal or Kool-Dam to make sure everything is water tight, carefully instrumenting, copiously irrigating, and then obturating with great style – how can we protect our painstaking work?

Here is a case where the root canal has been completed, but unfortunately, the final restoration – a ceramic restoration – has been made without replacing the cotton pellet and temporary base material. Even though the periapical lesion has healed nicely, the risk of coronal leakage, and thus the need for retreatment in the future again, is great.

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One nice way to prevent coronal microleakage is to definitively restore the teeth after root canal treatment. If you want to go one step further, you might consider an intra-orifice barrier. This is simply a (bonded) restoration that involves removing approximately 2 mm of gutta percha from the orifice of the root canal. Then, a material, such as glass ionomer, or composite, or MTA can be placed into the orifice. I also prefer to cover the furcation floor. I have been placing an intra-orifice barrier of glass ionomer (and often a 1 mm intra-canal barrier when I prepare post spaces), and then restoring the rest of the access with a bonded core material when indicated. The glass ionomer can be placed with a small plugger, or a Centrix Accudose needle tube.

I have also been trying a neat product as an intra-orifice barrier, PermaFlo Purple, which is simply a flowable composite that is colored purple. You can place a tooth-colored material on top, in the bulk of the access. I suppose the rationale of a purple-tinted flowable composite is to make any future treatment easier, since you’ll be looking for purple composite, instead of B2 composite! The case below shows a 2 mm intraorifice barrier of glass ionomer, extending below the floor of the root canal chamber.

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MB2: a Pain in the Neck.

When I went through my undergraduate dental training, I was taught that MB2 canals in upper molars are there 60-70% of the time.  Newer tools and techniques show us that MB2’s are always there whether or not we can get to it.  As a matter of fact I tell our endodontic residents at UBC that “if you haven’t found it, you have missed it“.

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Here are some pointers on how and where to find the canal that can potentially result in endodontic failure if left untreated, specially if the tooth is necrotic to begin with:

  1. MB2 is always there!
  2. It is always located palatal to MB1.
  3. It is always mesial to the line running between MB1 and P canals. This is the only safe area to trough.
  4. A good magnification and illumination is necessary.
  5. The access should be big enough to allow for adequate visualization of the pulp floor colour and map.
  6. Only instruments/burs (such as Munce Discovery Burs) that produce smooth troughing surface should be used. This is a more conservative and much cheaper option than using ultrasonic tips.
  7. There is absolutely no need for using explorer to poke and create misleading holes on the pulp floor.
  8. If there is no indication of the canal initially just start by troughing from MB1 mesio-palatally.
  9. Use copious irrigation to remove all debris created during troughing.
  10. The troughing should continue until a small size file can easily drop into this canal. This point of entry could sometime be 2-4 mm below the pulp chamber floor.
  11. Do not trough and hope you can find the canal. Always observe the colour changes on the floor and look for the clues.
  12. Know your limits and when you hear the whisper in your ears asking you to stop, listen to it!

The Pink Tooth

One of the reasons for a tooth appearing pink is the presence of External Cervical Resorption (ECR) or Invasive Cervical Resorption.  This type of resorption has been described and classified by Heithersay.

Some of the predisposing factors for ECR include: trauma, orthodontics, periodontal therapy, surgical procedures, intracoronal bleaching/restorations, etc.  For the reasons that are poorly understood, odontoclastic activity below the epithelial attachment would cause resorption that advances inwardly and, if untreated, eventually result in significant loss of crown and root structure. Resorptive process does not usually involve the pulp tissue and in most cases the tooth stays vital.  Teeth with Class 3 or 4 resorption have poor prognosis.  So, the key to saving these teeth is to catch the resorptive defects early on.

One of the telling signs is the presence of pinkish discolouration in the cervical area of vital teeth.  A resorptive defect harbouring a very touch-sensitive granulation tissue can be detected easily by running the sharp, curved end of the explorer below the level of CEJ.  The treatment of the resorptive defect is open-flap restoration.  The tissue residing inside the defect is usually very easy to remove as it appears detached.  As mentioned before, the pulp tissue is unaffected by this resorptive process and therefore, root canal therapy is not needed.

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One Cone Fits All, or Does It?

“After about ten years of first appearing on the market, currently Thermafil obturators are completely modified and form an integral part of a complete and sophisticated system of root canal obturation that, when used correctly, can give optimal results.   — W. Ben Johnson”

The reported advantages of Thermafil include: shortness of learning curve, speed of clinical application, apical control of fill, conservative enlargement of root canal (when compared to other warm gutta percha compaction techniques), three-dimensional obturation and apical sealing ability, etc.

In my opinion, shorter treatments do not allow for adequate disinfection of the canal system, speed compromises the quality, apical control of fill is nonexistent with this technique, and conservative enlargement of root canal is not always beneficial since some degree of apical enlargement is necessary to allow for proper disinfection by irrigants.

If used correctly (proper size obturator in a single, adequately-instrumented canal and following the manufacturer’s recommendations), 3-D obturation and apical sealing ability are the major advantages of this obturation technique.

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Inappropriate case selection for the use of Thermafil obturation technique is demonstrated above.  This case shows how Thermafil would give us a false sense of achieving an “optimal” obturation in challenging cases such as this.  There was only one obturator used in the canal system that splits into three apically.

As I mentioned in my previous post I Love Sealer Puffs!, extrusion of obturation material into the uncleaned and unshaped portion of the canal system (lateral canals, fins, isthmus, irregular areas, etc.) does not translate into success.  The prerequisite for any obturation technique is adequate shaping and cleaning of the entire system, and the only reason for endodontic failure is the presence of micro-organisms.


Alcohol Will Set Things Straight!

During re-treatment procedures, removing the gutta-percha dry (if possible) is preferred.  Simply because it is less messy.  But I often find myself use a bit of C-form (what we call chloroform in the office) specially when I have to negotiate the very last part of the gutta-percha close to the apex.  I also use it quite often when I re-treat cases with carrier-based obturation material.  And, what a mess that creates!

softened gutta-percha by chloroform

To get rid of this “soup” of gutta-percha from the access cavity and to continue working in a very clean and controlled environment, alcohol should be used as the next irrigant.  It clumps up all the softened gutta-percha to the point that it can easily be rinsed off by water spray or picked off by instruments.

Once the gross removal of gutta-percha from the canals is complete with alternating use of C-form and alcohol, I usually use EDTA as it will continue to clean the remaining of the softened gutta-percha from the canal system.

 


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