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.