Endodontic Retreatment

This patient came in with RCT #29 completed 7 years earlier. She reported dull ache, had a gold onlay and obvious apical lesion. Clinically, tooth was mildly sensitive to percussion, normal probing depths. Diagnosis: Prior RCT with Phoenix Abscess. Retreatment indicated.

During retreatment, a lateral canal was opened, irrigated & obturated. No fractures seen under the microscope.

At 3 months, the patient was asymptomatic and apical healing noted. This lesion is classified as "healing" due to the decrease in apical lucency since the retreatment.

At 15 month recall, the patient is asymptomatic and lesion is "healed", despite failure to place coronal restoration.

Swartz, Skidmore & Griffin (1983) in an evaluation of 1007 endodontically treated teeth found that the #1 reason for failure was inadequate restorations. They also found that overfills caused 4 times as many failures.

This patient was encouraged to get coronal coverage on this tooth ASAP.

Separated File Removed

Look closely and you can see a separated file in the mesial root.


The contrast feature makes the separated instrument a little more obvious.

For more information about removing a separated instrument, click here.

For information about PREVENTING a separated instrument, click here.

Length Determination with Radiographs

Apex locators have become commonplace in the clinical practice of endodontics. They have shown remarkable accuracy and reliability. Part of the skill in using an apex locator is understanding when the reading is reliable or not. There are certain conditions where an apex locator may not give a reliable reading and traditional length determination using radiographs is required.

For radiographic length determination we rely upon our files and radiographs. For a quick review of terms, the radiographic apex is where the apex appears on the film. The anatomic apex is where the apical foramen is positioned, which may or may not be at the most apical part of the root. When using radiographs to determine the length of the root, it is recommended that we estimate the length of the root from 0.5mm-1.0mm from the radiographic apex.

The reason for this estimation goes back to the early 1970's.

Palmer, Weine & Healy 1971 showed that when teeth are filled to the radiographic apex, the gutta percha is extruded out of the canal 50% of the time.

Burch & Hulen 1972 found that the apical foramen deviated from the anatomic apex 78%-99% of the time.

Because of these early length studies, it is recommended to estimate your length short by 0.5-1.0mm.

Here is an interesting case that demonstrates how filling to the radiographic apex may actually be filling long.


Here is a post operative film following RCT of #3. I think most people would assume that the obturation looks pretty good.

1 year recall looks good radiographically, however the patient continues to reports some sensitivity.

After some of the extruded sealer has resorbed, its easier to see that there is a slight over fill. Since the patient's symptom persist, the tooth is treated surgically

Surgical exposure of the root apices shows the extruded gutta percha and sealer.

Simple apicoectomy removes the extruded gutta percha.

This case shows how easy it is to overfill a root canal. Length determination using apex locaters as well as radiographs is an important skill for any clinician performing endodontic therapy.

Horizontal Root Fracture?

This tooth was referred to an oral surgeon for extraction and immediate implant placement on #11. A void between the post and the root canal filling is noted and it appears there may be some widening of the periodontal ligament adjacent to that void. There was purulence noted from the sulcus and the attached gingival tissue was inflammed. The tooth was otherwise asymptomatic. I was asked to do a consultation to confirm the horizontal fracture before the tooth was extracted. As I have mentioned in previous posts, root fractures are very difficult to diagnose.

A second radiograph of the tooth appears normal. No sign of fracture or change in the periodontal ligament from this view. It does appear that there may be some coronal leakage on the distal margin of the crown.

Another radiographic shift reveals that the post preparation was off center slightly with the canal. I explained to the patient and my oral surgeon colleague that the only way to know for sure would be to examine the tooth surgically or by removing the post and examining the tooth internally using the microscope.

When given the option to evaluate the tooth microscopically and potentially retain the natural tooth, the patient elected to disassemble the post & crown and evaluate it. Microscopic examination as well as additional radiographs revealed no sign of horizontal fracture. Endodontic retreatment was completed and a post and core build up was completed. There is plenty of supracrestal bone to get a good ferrule for the new crown.
Proper endodontic consultation allowed this patient to retain his natural tooth, save considerable time and money and be back to complete function in a matter of a few weeks.
The endodontic part of the "multi-disciplinary" approach to implant treatment planning is often lacking. Diagnosis of root fracture rarely can be made by looking at a single film. Endodontic consultation is an important part of implant treatment planning.

Removing a Separated Instrument

Have you ever wonder what it takes to remove a separated file? The position of the separated instrument has a lot to do with our ability to retrieve it. The closer it is to the apex, the more difficult it is to remove. Removing a separated instrument is a balancing act between removing enough tooth structure to dislodge the file and removing too much tooth structure and weakening or perforating the root.

This video shows the removal of a separated rotary file using an ultrasonic instrument. (watch closely and you will see the instrument fly out) The separated instrument has been located, coronal access to the separated file has been increased using Gates Gliddens. Under the microscope, the ultrasonic tip is used to trough around the separated instrument. One of two things will happen:
1. The instrument will loosen & sometime fly out
2. The instrument will break again & the procedure starts over again.
Removing a separated instrument can be a difficult procedure which requires alot of patience from the operator and the patient.
For helpful tips to prevent file separation, click here.

Retreatment Success

This patient came in 18 months ago. Tooth #30 was diagnosed with Prior RCT & Phoenix Abscess. Retreatment was recommended. As you can see, there is an apical radiolucency on the mesial roots, which appear to be filled short of the apex.

An amalgam was placed into the canal orifaces for retention of the core build-up. During the treatment, some amalgam shavings were pushed apically. However, I was pleased that we were able to open the canals better and get to the apex.

This patient returned today for a 18 month recall. The lesion has healed. The tooth is asymptomatic, fully functional & with normal periodontal probings. Endodontic retreatment is a valuable (and economical) treatment option that has helped this patient retain this tooth and the bridge.

Research Update: Comparison of Nonsurgical Endodontics & Single Tooth Implants

A recent study published in the Journal of Endodontics is one of the first studies to directly compare the outcomes of nonsurgical endodontic therapy (NSRCT) with single tooth implants.
Implants have long been accepted as a predictable treatment option for the replacement of missing teeth. However, recently, there are those who have begun to indicate that extraction and an implant may be preferred over endondontic treatment. There are those who argue that implants have a higher long term survival rate than teeth treated with endodontics. This is not an evidence based argument.
Until recently, there was no research directly comparing the survival rate of endodontics and implants. The endodontic literature defined "success" as complete radiographic healing, absence of symptoms, & full function. (A tooth that had incomplete radiographic healing at the time of re-evaluation would not be considered a "success" by this definition even if it was asymptomatic and fully functional.) In contrast, the implant literature defines their success as "survival". An implant was categorized as "surviving" if it was still in the mouth at the time of re-evaluation. (An implant with a draining sinus tract that had not been removed would be considered "surviving".) This difference in definitions has caused much confusion and mis-interpretation of the endodontic & implant literature.
The recent study by Doyle et. al. directly compared the NSRCT with single tooth implants. The retrospective study compared 196 NSRCT cases and 196 single tooth implant cases for success, survival, survival with intervention & failure. This definition of outcomes allows a more accurate comparison of the outcomes of endodontics & implants.
Their results were very interesting.



Their study found that NSRCT (when restored properly) and single tooth implants have similar failure rates over time. They also found that the implant group has a longer average and median time to function.

This study directly comparing implants and endodontics, while one of the first of its kind, will not be the last. Dr. Walter Bowles, associate professor at the University of Minnesota, will be leading a team of researchers to conduct a similar retrospective study on a much larger scale. Dr. Bowles and his associates from the University of Alabama, University of California, San Francisco, & Ohio State University, will be evaluting 10,000 patients and use the data to provide a timeline for outcomes over a 10 year period. The project which recently began will take two and a half years to complete.

Evidence based dentistry helps us to make treatment decisions based on the best available clinical evidence, individual factors of each particular case, the clinician’s expertise & patient’s informed consent. The decision to restore a tooth with endodontic treatment or remove and place an implant should be based on other factors than long term survival rates.

References:

Doyle S, Hodges J, Pesun I, Law A, Bowles W. Retrospective Cross Sectional Comparison of Initial Nonsurgical Endodontics Treatment and Single Tooth Implants. J Endod 2006; 31.

Hoffman, J. AAE-Funded Study to Compare Implants, Endo. The Endo Tribune 2007; 2:8, 2-3.

2nd Chances

We call it the practice of dentistry for a reason.

Today I had the chance to see one of the very first root canals I did after dental school. If I had to guess, I would say it was my 20th root canal. My friend was traveling to Arizona from Washington, D.C., and needed a root canal on #14. I had completed the root canal on #15 in my AEGD residency following dental school. This gave me the unique opportunity to look back in time at my own development as an endodontist.

When I first saw #15 my thought was, "I did that?" My second thought was, "thank goodness for second chances". Since his flight out of town left in a few hours, we quickly got to work. #14 was diagnosed with an irreversible pulpitis & acute apical periodontitis. #15 was diagnosed as a prior RCT with phoenix abscess.

With my friend's help, I recalled the situation. He was a huge dental phobic, he arrived in tears, the tooth was abscessed, I was working without a microscope & I had less than 2 dozen root canals under my belt.

What a difference of few years of practice (several thousand RCTs) and a microscope can make. We were able complete the RCT #14 and retreat #15 easily.


I expect the periapical lesion on the MB root to heal and that my friend will have both of these teeth for a long time.

Thank goodness for 2nd chances!

Apical Surgery Saves the Bridge

This root canal was orginally done in 1982 and an instrument was separated at the time. Within the next two years, the tooth was treated with an apicoectomy to remove the separated instrument. This was "Old School" endo surgery. No microscope with an amalgam retrofill. Despite this, the tooth was retained (survived) for 25 years. You can tell that the amalgam retrofill came loose and the apical seal was jeopardized. An apical radiolucency is apparent.

We discussed with the patient the possibility of a root fracture, but that the most likely reason for the apical lesion was the lost retrofill. We recommended endodontic microsurgery to retreat the lost retrofill. The patient agreed and procedure was peformed.

A root end fracture was found. At this point, we decided to go ahead and resect the root to see how far the fracture went. (I decided that rather than remove more bone looking for the dislodged amalgam, I would leave it.)

Under the microscope we were able to remove the fractured portion of the root. We went ahead and placed a retrofill with MTA (Mineral Trioxide Aggregate).

Post-operative radiograph following placement of new apical retrofill.

A six month recall on the tooth reveals complete healing of the bone and full function of the tooth. No pain to percussion, normal probings. Despite a small root end fracture, this tooth was treatable with endodontic microsurgery. The endodontic microsurgery option has allow this patient to retain his natural tooth and keep his 3 unit bridge.

Finding the canal in a Md Incisor

This tooth was referred to my office today after the RCT had been started. I appreciate a dentist who is not afraid to stop during a procedure and refer if needed. Here's a tip to help you find these canals.

Look lingually. The natural access into a Md incisor always goes toward the buccal. If you cannot find the canal (or the second canal in 20-40% of these teeth), look lingually.

I used an ultrasonic tip under the microscope to cut from the current access back towards the lingual.

That's it. Remember to look lingually.