Category Archives: Retreatment

A Compromised Tooth is Still a Tooth.

In my previous post “What to do with a compromised tooth?” I asked everyone about the options for a tooth which appeared to be compromised on X-rays.  Four options were presented: a) endodontic retreatment, b) apical surgery, c) extraction/implant and d) other.  Apical surgery won the race and all responders chose one of the first three options given.  In this case, the fourth option was chosen: Intentional Replantation.

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Intentional replantation procedure allows us to control all the contributing factors to endodontic failure in this case: ruling out the presence of root fracture, removing the subgingival calculus as a result of loss of enamel, removing the resorbing granulation tissue, eliminating possible established extra-radicular infection or biofilm, sealing the root-ends without the need for retreatment and possible further extrusion of obturation material into the lesion, preserving the intact buccal and palatal cortical bone through eliminating the need for apical surgery (Risks: proximity to Greater Palatine nerve and artery, inadequate palatal root length, possible loss of palatal cortical bone post-surgery).

The final radiograph shows the periapical healing after 1 year. Patient is asymptomatic, the tooth is functional with great periodontal health post-restoration, awaiting a crown. Extraction/implant option can wait for now.

Office website: vanendo ,  FaceBook page: @endospecialists

What to Do with a Compromised Tooth?

Endodontic diagnosis for tooth #27: previously treated, symptomatic apical periodontitis.  I/O examination reveals a wide, 6-8mm clinical attachment loss (i.e. probing defect) distal to tooth #27 and loss of distal contact due to enamel fracture.  A CBCT scan shows intact buccal and palatal bone and a significantly shortened palatal root due to external inflammatory root resorption.

intentional replantation

intentional replantation

Office website: vanendo ,  FaceBook page: @endospecialists

The Non-precious Stone

The only non-precious stone that I know is the pulp stone.  One of the factors contributing to root canal failure is remaining infected pulp tissue and the pulp stones, if left behind unnoticed, are the main reason for trapping tissue and retaining infection. Pulp stone removal is therefore a crucial factor in achieving a successful result in endodontic treatment.  The following case shows how a large pulp stone can result in failure of a reasonably well done root canal treatment by trapping infected tissue, hiding the MB2 canal and retaining infection.

Proper access cavity (i.e. adequately large and at the level of the CEJ) in order to visualize the outline of the pulp stone/chamber floor is the key in removing it completely.  In the above example the pulp stone is easily dislodged by troughing around it using a large diamond-coated ultrasonic tip and applying the energy directly to the calcified tissue. For demonstration and documentation purposes, no water was used in this case; however, it is highly recommended to use water for its cooling effect and in order to facilitate the debris removal.

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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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!

Your Tooth Broke My File!

“A dentist who has not separated a tip of a file, reamer, or broach has not done enough root canals.” — Louis Grossman

There are essentially 2 reasons for rotary rotary instrument separation inside a canal:

1) Cyclic fatigue (file rotating inside a curved canal for extended period of time):
Factors contributing to cyclic fatigue are: overuse of rotary NiTi files, spending too much time inside the canal during instrumentation, canal curvature (degree and abruptness of the curvature), improper speed setting for the handpiece and the file tapers (larger tapers break faster).

2) Torsional fatigue (too much friction between the rotary file and the canal wall):
Factors contributing to torsional fatigue are: improper endodontic access, using too much apical pressure during instumentation, not following the proper sequence for a particular file system, not using lubricating agent/irrigants, using greater tapered files inside a tight/calcified canal and using handpieces with no torque control or auto reverse option.

Attempting to control the factors above will greatly minimize the risk of file separation.  But even in a perfect situation, a patient’s canal anatomy can bring the man-made technology to its knees.

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What to do if a file breaks inside a canal?

1. Stay calm. It is not the end of the world.

2. Try to remove it only if the separated portion is in the coronal segment of the tooth and not past the root curvature. This step also requires good magnification, illumination and proper tools (such as different ultrasonic tips).

3. Bypass it if the separated segment is apical to the curvature of the root using hand-instruments and finish the shaping of that canal with hand-files. Sometimes the separated file comes loose and can be easily flushed out.

4. Make it part of the filling if the file has completely blocked the canal. This may not affect the prognosis negatively [Crump and Natkin 1970, Spili et al. 2005] depending on the initial status of the pulp and whether or nor the separation happened towards the beginning or the end of cleaning and shaping stage.

5. Follow up the healing and the resolution of symptoms. Endodontic surgery may be needed if symptoms persist or the PA lesion does not heal.

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.


Ruddle to the Rescue!

Removing posts from canals could be pain in the neck sometimes. There are many ways to remove a post from a canal such as cutting all the sound tooth structure around the post with a large round bur (I hope nobody is using this method) or using ultrasonic device and frying a few expensive tips and ultimately the root and surrounding structure (can you smell the lawsuit?).

One method that has allowed me to remove stubborn posts more conservatively and relatively quickly is using the Ruddle Post Removal System (PRS) Kit.

The kit comes with a series of post removal trephine burs (#1 to #5) and corresponding post removal tubular taps. The process of port removal starts by removing the majority of the build-up material from around the post. Then a trephine bur can be used to mill the post to a specific size (usually the biggest size that starts to mill the post). The corresponding tubular tap is then used in counter-clockwise direction to engage the post. The tap is screwed in to the point that it locks and starts to disengage the post from the canal. If the post cannot be removed easily, the extracting plier and cushions will do the job beautifully. The short video clip below demonstrates how easily a post can be removed from a canal:

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