Persistent Post-Treatment (Apical) Periodontitis.

When endodontically treating a tooth experiencing symptoms to percussion, that is symptomatic apical periodontitis or acute apical abscess, it is reasonable and normal to expect those symptoms to persist a few days following treatment. I make it a point to explain to patients that this sensitivity is emanating from the periodontal ligament surrounding the tooth, and, just like a sports injury, ligaments require time to heal following removal of the insult (bacteria in teeth). However, occasionally we evaluate a tooth that has had symptoms to percussion for an extended period of time. In this post, I will discuss the sources of these symptoms and how to diagnose and treat them. I will also show a few cases of persistent apical periodontitis and how they were managed.

Before we get into diagnosis and cases, it is essential to understand the sources of apical periodontitis. With few exceptions, the source of symptoms is either trauma, occlusal or otherwise, or bacteria, apical or otherwise. It really is that simple. It is up to the clinician, through history and exam, to determine the source of symptoms.

Briefly, a common scenario would be a tooth with an apical radiolucency, sensitivity to percussion, and a lack of cold response. Our diagnosis is necrotic/symptomatic apical periodontitis and the source of both is bacteria. By removing the insulting bacteria with root canal therapy, we can resolve the apical periodontitis and the radiolucency will heal with time. The below images are from a patient with that exact scenario and illustrate an important point.

This #18 clearly has a challenging s-curvature in the apical third of the mesial root. If we are unable to instrument and clean around that curve, we run the risk of bacteria persisting, and consequently, symptoms persisting.

Fortunately, with a little luck, I was able to clean around the curve and the patient's symptoms resolved within a day of initiation of treatment and calcium hydroxide placement. Also, note the mid-mesial canal. There is an important point here:

With a necrotic tooth, if symptoms persist following treatment, especially if the treatment is deficient in cleaning or rife with errors such as a perforation, then we must suspect bacteria as the source and look to treat the tooth endodontically (possible retreat and/or surgery).

Here is another scenario, this patient was referred for evaluation and treatment of symptoms in the lower left. Symptoms were described as a short, sharp sensitivity to chewing over the past year and a half, and a moderate sensitivity to hot and cold that lingers for a few minutes over the past few months. The patient points to #19 for the chewing sensitivity and farther back for #18. Clearly, we have two issues at hand as an endodontically treated tooth will never cause the type of sensitivity described by the patient.

The previous root canal treatment was done by an endodontist a year and a half ago. This endodontist evaluated the patient and placed him on penicillin and methylprednisone. I must stop here and say that I do not support treating this situation with these medications. I have never felt compelled to prescribe steriods and rarely prescribe antibiotics. It is easy to understand why when we realize that neither of these medications will address the possible sources of the patient's symptoms. Permanently resolving the inflammation will not happen without removal of the trauma source and systemic antibiotics will not have any effect on bacteria within a root end. Symptoms can be masked, but even a placebo can help a patient's symptoms. In this case, following medication, there was some improvement in symptoms but they soon returned.

Let us ignore the cold sensitivity for a minute, which was traced to #18, found to linger and be associated with a cracked tooth, and was treated appropriately. What questions are important to ask the patient at this point? Maybe we can deduce the diagnosis of #19 prior to treatment. As it turns out, with more specific questions, I learned that the tooth was cold sensitive prior to root canal therapy, and that these symptoms resolved. I also learned the tooth was actually asymptomatic until the crown was placed a few weeks following treatment. Now, I can proceed to the clinical and radiographic exam knowing that the most likely cause of apical periodontitis is a traumatic occlusion, since even a poor root canal on a vital tooth will likely be asymptomatic for many years before bacteria can negotiate to the apex.

Exam revealed #19 to be sensitive to percussion and bite forces (in MI and with a bite stick), and #18 to be hypersensitive with a prolonged cold response and a fracture. I also located a 5mm ML probing depth with associated erythematous and edematous gingiva. The crown on #19 was bulbous, overhanging the lingual, and flat on the occlusal with wide contacts.

In the below radiographs, we see a short obturation on the mesial and distal roots of #19 with some slight and debatable ligament widening. Not a perfect root canal but unlikely to be the source of symptoms.

Another radiograph revealed overhanging cement on the mesial.

Local scaling removed the excess cement and crown recontouring with a diamond bur combined with an occlusal adjustment was performed. The patient returned for treatment of #18 a few days later and all his symptoms from 19 had resolved. A reevaluation in a few months will determine if our treatment worked permanently. Incidentally, here is the completed treatment on #18 (and check out the distal root of 17 curving at the x-ray plane).

The point to be learned from this case is that an accurate and complete history will illuminate possible sources of the problem, exam can confirm that source, and conservative local treatment will often be enough to resolve symptoms. Occlusal trauma is the most common cause of post-treatment apical periodontitis.

Here is a case I treated that exhibited persistent symptoms and is similar in many respects to the one above. The original symptoms and exam were indicative of irreversible pulpitis and extensive recurrent caries was located underneath the buccal margin. I painted a grim picture and recommended extraction. The restorative prognosis was compromised, decay reached into the furcation and alveolar crest. Nevertheless, the referring dentist was confident and capable, and the patient was well informed knowing the risks and that periodontal therapy was in her future. She was anxious to avoid implant treatment due to a prior bad experience with one in another site.

At the second visit of treatment, the patient reported her symptoms to cold had quickly resolved. However, her tooth that was not previously symptomatic to percussion was now hypersensitive to occlusal forces. I had not cleaned long at the first visit, and I had not yet placed the obturation material (not that these usually cause any problems). Likewise, I had merely placed CaOH within the top of the orifices as a barrier to reinfection and not deep into the canals (again, not that this usually causes a problem). The tooth was out of occlusion as well so the only possible source of ligamental inflammation was the buccal area where decay had been removed to the level of the alveolar crest and into the furcation. This area was not well restored yet, merely patched with IRM, and was a definite irritant to the ligament. I cautioned patience, completed treatment, and recommended returning to her general dentist for evaluation and restoration.

When the patient returned for reevaluation a month later, complaining of chewing sensitivity in the temporary crown, I was impressed with the quality of the buccal composite restoration and the buccal gingiva was minimally inflamed. The distal gingiva was inflamed with bleeding on probing. The patient had plans for an evaluation with a periodontist and I again counseled patience with symptoms until all periodontal treatment was complete. The occlusion was found to be heavy in non-working lateral excursion and adjustment relieved the patient's symptoms in the chair.

The important point here is since I had done the initial root canal treatment, I knew that the tooth was vital preoperatively. There is no way I would consider touching this tooth with any endodontic therapy since I know that I cannot improve upon my root canal treatment. The dental history leads me to look for sources of trauma to the ligament, occlusion and biologic width infringement in this case.

One other common cause that I see of persistent apical periodontitis is when a patient wears an occlusal splint or night guard, dentist fabricated or store bought, that is not well adjusted following a new crown on the tooth. Consider how a kids teeth feel after an orthodontic visit and you will understand the source of these symptoms.

This last case was treated by a general dentist 2-3 years ago and has exhibited persistent symptoms that have only seemed to worsen through multiple occlusal adjustments. The dentist reports an instrument separation in the distal root. Her symptoms had only recently become spontaneous and were described as a minor dull ache or pressure. In discussing the situation with the patient, she remembered the tooth being asymptomatic and the crown having been placed years prior to the root canal treatment. She claimed the referring dentist saw signs of a problem on the radiograph and recommended treatment through the crown. Clinical exam revealed no relevant findings and occlusion appeared well adjusted. A distal shift radiograph, the most important radiograph to take on a maxillary molar, displayed an all too common radiographic finding in maxillary molars treated without a microscope, a radiolucency on the mesial root.

The most common cause of this problem and one that we see every week is a missed MB2 (also called MP or ML) canal. This tooth was unusual in that I speculated a missed MB canal outlined below.

Upon retreatment, the untreated MB canal was found and is seen on the below photograph and radiograph.

The patients symptoms resolved quickly following the first visit. Here is the post operative radiograph.

Not all cases of persistent apical periodontitis require endodontic retreatment or surgery. In fact, most don't. By a taking a careful dental history, it is often possible to discern the preoperative diagnosis, which informs how and where bacteria could be causing a problem. It is also possible to create a timeline as to when symptoms first occurred and what events could have initiated them. If symptoms started with restorative work, then carefully examine the occlusion, margins, and gingival health. Only when we have a radiolucency or a smoking gun, like a missed canal, a short obturation in a previously necrotic case, or a case recontaminated with recurrent caries, should we be looking into endodontic therapy as our first choice to solve the problem. Often times, diagnosis is not clear, and I start with the conservative options, occlusal adjustments and periodontal therapy, before proceeding to endodontic therapy. I cannot think of a single instance where I have recommended medication as a primary therapy.

I hope these cases will help those of you out there to think like an endodontist. Some may point out that I have not talked about tooth fractures. I plan to discuss my philosophy on those in future posts. I look forward to any feedback and invite everyone to check out more cases on our facebook page: http://www.facebook.com/pages/Alpharetta-Endodontics/137382942943581

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.