The Blame Game - Root Canal Failure?

CASE #1
I recently completed a diagnostic excavation on this tooth and determined that it was non-restorable due to decay under mesial crown margin and into the pulpal floor of the tooth. The findings of the implant surgeon indicated a "failed root canal" as the cause for extraction.

It is well known that a common reason for endodontic failure is root canal recontamination caused by coronal leakage. If coronal leakage allows bacteria to re-enter the root canal system, then did the root canal fail or did the restoration fail? In this particular case, when rampant caries is found under the crown margin and extending into the pulpal floor, it is more accurate to say that extensive recurrent decay is the reason the tooth is non-restorable requiring extraction.

A review of the root canal history also confirms that endodontic therapy was successful.

This pt presented in 2006 with an prior rct & acute apical abscess. Retx was recommended. A periapical lesion is noted on the distal root.

Retreatment completed in 2006.

In 2010, the patient returns with symptoms. The distal lesion has healed, and the mesial margin of the crown shows leakage. It is recommended to remove crown and excavate decay.

The radiographic history would indicate that the endodontic retreatment performed in 2006 was was successful with healing of distal lesion.

When a tooth is to be extracted, a proper diagnosis should be given.

CASE #2

This patient came to our office today for consultation. Pt reports that RCT was done many years ago without any issues. Last year he traveled to Mexico for some dental work. The crowns were placed on #30 & #31. A periapical lesion has now developed on the mesial root of #30. My diagnosis is: prior RCT w/ symptomatic apical periodontitis. Coronal leakage is identified radiographically on mesial and distal margin. In this case, you could easily say the root canal failed. However, the inadaquate coronal seal on #30, in my opinion, is just as likely the cause for the periapical lesion on the MB root.

In our practice at Superstition Spring Endodontics, we would diagnose #30 as: Prior RCT with SAP (symptomatic apical periodontitis - percussion pain) with coronal leakage. Retreatment would be recommended. We would explain to the patient that for long term success, we need to prevent any leakage from above. (We would also recommend evaluation of mesial margin #31 by general dentist)

A proper diagnosis does not cast blame. It objectively reports current findings and indicates the reasons for recommended treatment.

Success with endodontic surgery (apicoectomy)

This patient was kicked in the face by a horse in 1998. Teeth were displaced (luxated). She repositioned them herself. RCT's on #24 and #25 were done in 2008 by her general dentist. In
Jan 2011 she is having pain, percussion sensitivity, normal probings, adjacent teeth WNL. These teeth are diagnosed as: Prior RCT's w/ Symptomatic Apical Periodontitis.

Axial and sagittal views in CBCT verify that these are single canals incisors. It also shows us the extent of the bone loss prior to our surgical access.

Due to the large size of the canals and over extension of the previous RCT, it was recommended to treat these teeth surgically with an apicoectomy.

Apicoectomy completed with MTA retrofill.

At 6 month recall the teeth are fully functional and asymptomatic. Radiographs show impressive healing of the apical bone. Endodontic surgery can preserve the natural tooth, which then helps to preserve the periodontium.


UPDATE: 1 year recall. Pt asymptomatic, fully functional.

CASE #2

The following case is a similar, double apicoectomy. The CBCT confirmed that there were no missed canals. The large posts and good crown margins were the reasons we chose surgery over non-surgical retreatment.

Endodontic surgery saves natural teeth.

Evaluation of #2 for Retreatment, CBCT Revisited.

I want to thank Dr. Hales for the introduction and for inviting me to contribute here on the Endoblog. I've been following and learning from the Endoblog for some time. It's my hope that I can not only share some of my knowledge, but also receive some valuable feedback from others who read this blog with other experiences and points of view.

Many interesting cases, treated by myself and Dr. Stephen Parente, can be found on the Facebook page for our practice: http://www.facebook.com/pages/Alpharetta-Endodontics/137382942943581 I would urge those interested in endodontics to check us out there as well.

This past week, I evaluated a patient who's tooth reminded me of the case previously presented here on June 7th by Dr. Hales. Since it was so similar, I thought it would be a perfect follow up and first post. This patient had #2 treated with root canal therapy 1 year ago by another endodontist. I am familiar with this endodontist's work from other patients requiring retreatment and know that he does not use a microscope. He also tends to limit most treatments to one visit.

The patient described symptoms as an occasional spontaneous dull ache of varying intensity that has persisted since initial root canal treatment. At worst, the symptoms are moderate with some pulsing or throbbing. At the time of evaluation, the patient was experiencing a mild awareness of the tooth, a common description of symptoms from a failing root canal. Prior to root canal therapy, symptoms were similar, but more intense, and the patient has no recollection of any hot or cold sensitivity at that time period. From this information, we learn the tooth was likely necrotic prior to treatment, which is relevant when understanding possible challenges to disinfection. The symptoms are well localized, and the patient points directly at tooth #2. The tooth has been reevaluated by the previous endodontist and by the referring dentist. They adjusted the the occlusion and prescribed antibiotics.

The relevant medical history consists of prior dual knee replacement surgeries in 2009 and 2010 necessitating antibiotic prophylaxis. The patient is currently taking clarithromycin (Biaxin) for a sinus infection, but the tooth symptoms predate the sinus problems by many months.

Extraoral exam revealed no relevant findings. Intraoral exam revealed normal tissue contour and consistency with no swelling or sinus tracts. All probing depths were 2-3mm and percussion and bite tests produced only a mild discomfort on #2.

In addition to the above two radiographs, I also examined a bitewing and two traditional film radiographs which I chose not to include here. One thing that stands out is that the crown margin is placed on the buildup, not an ideal situation. You can see only two canals treated and an in tact PDL. The orifices of the canals are clearly overenlargedand the obturation does not appear to follow the root anatomy.

Drawn below is what I drew for the patient, predicting the true root and canal anatomy of the tooth and showing where I speculated there to be an untreated distal buccal canal.

It appeared as if the previous operator perforated during instrumentation, not only between the mesial and distal roots, but also at the apex. In addition to these root perforations, the coronal tooth structure is clearly compromised. The patient was anxious to save the tooth since she invested in root canal treatment and a crown within the last year. I did not feel retreatment would have a good prognosis and recommended extraction. The patient was understandably reluctant about this option, and so I opted to image the tooth with CBCT for more information and better patient education.

In the below left image, I circled the missed DB canal. The below right images (one is reversed, please forgive me) display the missed DB root in the sagittal plane as well as the apical perforation and over enlargement (strip perforation) of the MB root.

The below horizontal slice displays the previous instrumentation into the furcation between the MB and DB roots. I question if the radiolucent line mesial to the radiopacity is a fracture.

The left and below images show a palatal radiolucency forming as well as the off center and possibly apically perforated palatal obturation.

This last image to the left is a horizontal slice in the apical third of the root again displaying the palatal radiolucency forming.

The CBCT shows this tooth has many problems that are not reliably correctable with endodontic retreatment. Finding the missed DB canal and even repairing the MB perforation in the furcation will not help recapture the correct path of the MB or P canals.

The CBCT confirmed with certainty what was highlighted in the periapical radiograph above. With these images, the patient was better able to visualize the root anatomy and obstacles to repairing this tooth. Consequently, the patient was much more accepting of the treatment plan of extraction.

We are increasingly using the CBCT as a diagnostic tool in our practice, specifically in complex retreatment cases or in vague diagnostic situations. In this specific case, the CBCT images confirmed suspicions about root perforations and missed anatomy. They also displayed a palatal radiolucency that was not evident on the periapical radiographs. Lastly, and not to be overlooked, the images were invaluable for patient education and treatment plan acceptance.

All CBCT images provided by Dr. Colin Richman and his Kodak 9000.

The Endo Blog Welcomes a New Contributing Author - Dr. Justin M. Parente

We would like introduce and welcome a new contributing author to The Endo Blog, Dr. Justin M. Parente of Alpharetta Endodontics (Alpharetta, GA).



Dr. Justin M. Parente is from Alpharetta, GA. After undergraduate studies the University of Georgia, he attended dental school at the Medical College of Georgia. While at dental school, he earned awards for clinical excellence in both periodontics and endodontics, as well as awards for academic achievement and the highest score on the national boards. Dr. Parente was recognized as distinguished Hinman scholar and was inducted into OKU dental honors society upon graduation. He then completed the two year endodontic specialty program at the Medical College of Georgia. At the annual meeting of the American Association of Endodontists, Dr. Parente presented and won an award for his research on endodontic irrigation. Dr. Parente lectures and mentors students in endodontics at the Medical College of Georgia. He lives in Alpharetta, GA and enjoys playing guitar, reading books, and drawing art.

Dr. Parente has presented at the American Association of Endodontists annual meeting and at his local chapter of the Seattle Study Club. He serves as a scientific advisor for the Journal of Endodontics, peer reviewing research submissions.

He is a member of the American Association of Endodontists, the Georgia Association of Endodontists, the American Dental Association, the Georgia Dental Association, the Hinman Dental Association, the Northern District Dental Society, Southern Endodontic Study Group, the Alpha Omega Dental Society and the Seattle Study Club.

Welcome Dr. Parente!

To Scan or Not to Scan?

This patient had RCT #2 done about 8 yrs ago in the military. She is reporting pain of several days duration. Today it is percussion sensitive, normal perio probings, no swelling or palpation tenderness. Adjacent teeth are WNL.

Radiographs reveal peripical radiolucency and conical shaped root. Two canals have been filled. My assumption is that this is likely a c-shaped canal that was incompletely treated. We decided to take a CBCT to evaluate the root form to determine if there is a missed canal or c-shaped canal. If a canal is missed, then retreatment will be recommended. If all the canals were found, then we might consider a surgical approach.


I was surprised to see a large resorptive defect on the DB root surface. This defect has destroyed most of what was once a DB root. Non-surgical retreatment of this tooth would result in perforation and extrusion of RCT material, and likely failure. It was determined that surgical treatment of this tooth would also have a poor prognosis as well. Extraction has been recommended.

Also noted was a perforation in the floor of the Mx sinus, with adjacent sinus inflammation. This tooth is also causing a sinusitis of dental origin. Removal of this tooth should help clear up some of the chronic sinus issues the patient has been experiencing.

Another example of CBCT showing what you cannot see in a traditional radiographic image. Neither of these problems were identifiable with regular imaging and were not the purpose were were taking the scan. However, identifying the root resorption and the sinus perforation had a significant impact on the diagnosis and treatment plan for this patient. The CBCT is a valuable tool for case selection which improves the rate of successful of endodontic treatment at Superstition Springs Endodontics.

3D Evaluation of Root Canal Morphology (Cone Beam Computed Tomography)

At Superstition Springs Endodontics, the use of cone beam computed tomography (CBCT) is a valuable tool in endodontic diagnosis and treatment. This technology is used on a case by case basis, following the guidelines specified in the joint position statement by the AAE and AAOMR.

The joint position statement by the AAE and AAOMR regarding the use of CBCT in endodontics states that "The patient’s history and clinical examination must justify the use of CBCT by demonstrating that the benefits to the patient outweigh the potential risks. Clinicians should use CBCT only when the need for imaging cannot be answered adequately by lower dose conventional dental radiography or alternate imaging modalities."

A significant concern noted in this position statement is the added radiation dosage to the patient. In our practice, using the J. Morita Veraviewepocs 3De, the patient is exposed to the lowest radiation dose on the market. A single 40 x 40mm 3D scan exposes the patient to 0.029mSv. This is approximately the same amount of radiation a patient would receive with 9 digital periapical films (0.003mSv).

The volume of data acquired in a single scan allows us to look at that tooth from any coronal, sagittal or axial view, and the ability to re-slice the volume at any slice thickness. This volume of data can be manipulated over and over to gather unlimited amount of information about the tooth and it's periapical tissues.

A CBCT scan, provides visualization of root number & anatomy, canal number & morphology, much more accurate evaluation of peripical tissues. Understanding the advantages of CBCT, the limited radiation and limited liability associated with a focus field CBCT, I would suggest that the benefits routinely outweigh the potential risks. Unfortunately, there are often benefits of a CBCT scan that are not apparent unless the scan is taken. The following case is an example.

This patient presented with complaint of pain in lower left quadrant. Recent crown prep on #19. Regular diagnostics were inconclusive as to the source of this pain (#19 was testing normally to vitality, probing and percussion testing) A short obturation of #18 was noted, but this tooth was asymptomatic. After short period of time waiting to see if symptoms localized, and failure to do so, a CBCT scan was acquired to evaluate if there was apical bone loss associated with one of these teeth that would help in the diagnosis.

CBCT did not show any radiographic lesions on #18 or #19. The temporary crown #19 was removed for additional pulpal testing. Tooth #19 gave no response to cold on the buccal side and a vital response on the lingual side. It was decided that endodontic treatment should be initiated on #19 with a probable "partially necrotic" pulp.

The CBCT gives us valuable information about tooth #19. For example, following CBCT, prior to starting RCT #19, we know that the mesial root is a single root with 3 canals that merge. We also know that distal root has a single canal.

3 canals found in a single, mesial root. This was identified prior to treatment with CBCT. In this particular case, the 3rd (middle) canal would likely not have been found due to its location.

In this case, the CBCT identified a variation in the mesial canal morphology. Knowing that the mesial root was a single root and that it had 3 canals, gave me the ability & confidence to explore the ML-MB groove to a greater depth than would have normally been done for fear of perforation. This is a perfect example of radiographic information that is not available through traditional 2D imaging. This information allowed us to provide better cleaning, shaping and obturation, which will lead to a better RCT.

Endodontic Retreatment - Another Tooth Saved!

DX: Prior RCT w/ Chronic Apical Abscess
Huge periapical lesion noted. A thin, short (mesial) and long (distal) obturation.
Retreatment recommended.

Retreatment completed.

4 month initial healing seen.

2 yr recall shows fantastic healing. This tooth could easily have been condemned and extracted initially. Proper diagnosis, and ability to improve the cleaning, shaping and obturation allowed this tooth to be saved. Endodontists are specialists in saving teeth.

CBCT to Evaluate Apical Lesions

We have been discussing the use of CBCT in the practice of endodontics. There have been questions about whether CBCT is really necessary, or just another cool image. That particular question was one of the biggest we had in our decision to move to CBCT. We also ask that question to ourselves when we recommend a CBCT scan to our patients. However, much like a microscope, until you look through the scope, you often don't know what you are missing. I have found that quite regularly, I will find things that I could not have seen otherwise and it has changed the treatment that I have recommended.

Here's an example of a routine CBCT scan that I did prior to endodontic surgery. This scan gave me added information, that then changed the treatment plan and give us better prognosis.

This patient presented for evaluation. The teeth are asymptomatic, but a lesion seen by his general dentist. The lesion is obviously on the MB root of #3, with ledged MB canal. The crown margins looked good and since the MB canal is ledged, we were planning to treat this tooth with an apicoectomy. I recommended a routine, pre-surgical CBCT to evaluate the root anatomy, sinus proximity and buccal bone contours.


This slice through the MB root shows that there is a missed MB#2 canal.

A slice through the palatal root shows a periapical lesion on the palate not visible in the original, pre-op radiograph. This now changes our treatment recommendation. An apicoectomy will resolve the MB issues, but fail to resolve the palatal lesion. This could cause continued problems and lead to the assumption of a failed endodontic surgery, when the palatal root could be the problem.

An additional slice through the palatal roots shows that #2 also has a significant periapical lesion requiring treatment.

A sagittal view of #2 again shows the extent of the lesion.

While the lesion on the palate of #2 is visible in the original radiograph, there is no doubt about it's presence with the sagittal view above.

In this case the additional information about the palatal lesion on #3 changed the treatment recommendation and will thereby improve the prognosis. Lack of CBCT scan in this case would have led to wrong treatment recommendation.

That being said, I know there are those who will say..."alway retreat first" and you don't need a CBCT scan to make that decision.

CBCT provides improved imaging of the the teeth and periapex. I welcome the added information into the diagnostic and treatment part of my practice. For more information about the application of CBCT into endodontics, the upcoming Inner Space Seminar is right around the corner.

Implant Training by Mentorship!!!!????

I think we all agree that continuing education is one of the foundations of every profession.

It guarantees that practitioners remain up to date and abreast of new techniques, materials and research studies that are continuously changing and improving.
With that in mind, I have noticed a trend in the past two years that in my opinion is alarming, if not outright dangerous for the dental profession.

Recently many, for profit, seminar groups, institutes and other continuing education providers are marketing so called “Implant Mentorship courses”. Most of these courses are 2-4 days. Most faculties are general dentists and they claim they provide training for implant placement and restoration in that time period, through “mentoring”.
As an educator and a practitioner; I believe these kinds of so called “training”, will only give a false sense of knowledge and competence to people attending them.
The advances in implant dentistry have been wonderful for patients who are missing one or more teeth. In my opinion, any general dentist, who is interested in implant dentistry, should seriously think about attending these courses.

The best continuing education training programs in implant dentistry are offered by dental schools through out the United States. These programs are spread over a few months (usually about 300 CE hours or more) and all aspects of implant dentistry from A – Z are covered.
Faculties are periodontists, oral surgeons, prosthodontists and general dentists. And, they will tell you at the end of these programs, that you should not take on certain implant cases due to level of difficulty or possibility of complication. Keep in mind that a poorly done endodontic case, can easily be corrected by retreatment or apical micro-surgery. A poorly done implant case, is very very difficult and sometimes impossible to correct.

From a legal point of view,when a general dentist begins to perform procedures that are primarily performed by specialists, the law holds them to the standard of care, expected of specialists providing similar procedures on a regular basis.
Before you sign up for one of these implant training or mentorship courses, stop and think. Would you have an implant done on yourself or a loved one by a dentist that had training for 2-3 days?

I welcome your comments.

Robert Salehrabi, DDS

Did you know that 70% of Americans are afraid of root canals?

Root canal treatment allows patients to save their natural teeth. The endodontists at Superstition Springs Endodontics are partners with general dentists in helping to save natural teeth. Modern, microscopic endodontic treatment can be a relaxing and pain-free experience.

In a recent AAE survey, 76 percent of participants said they would prefer a root canal to tooth extraction.

Nearly a third would not sell a healthy front tooth for any amount of money.

Most people are not aware that root canal treatment is a viable alternative to tooth extraction

Despite great progress in modern endodontic therapy, there are still misunderstandings about root canal treatment.

Myth #1: Root canal treatment is painful.
Myth #2: Root canal treatment causes illness. (focal infection theory still persists today!)
Myth #3: A good alternative to root canal treatment is extraction.