Re: Failure of Root Canal Treatment Misdiagnosed as Neuropathic Pain


I wish to comment on this article1 and what I consider its serious problems.

  1. I find it difficult to believe that 2 endodontists missed an MB2. Most endodontic specialty practices treat/retreat a very high percentage of molars in their practices (80% or more). A missed MB2 is the first thing an endodontist would look for in a symptomatic maxillary first molar.2 Three filled canals? That is a red flag and it is one of the first things you learn in graduate school. 

  2. Was more than one conventional preoperative radiographic image taken by any of the clinicians (shift shots)? If not, why? Without it, the endodontic examination is incomplete. Any third year dental student should understand this concept. The missed MB2 could have likely been anticipated with this “low-tech” method.

  3. The use of the “odour test” is unscientific. Odour can be from several different issues that may have nothing to do with the periradicular status. Nose culturing is unscientific.

  4. Why was the patient prescribed an antibiotic after the initial retreatment appointment? There is no support in the literature for medicating patients with antibiotics “just in case”, and especially in cases where there is no intraoral swelling. Had the patient experienced an allergic reaction or untoward response to the medication, the administering clinician would have no defendable legal basis for prescribing its use in this instance.

Modern endodontic treatments are an easy solution for this case. The use of a focused field CBCT could have easily, reliably and predictably shown the presence of an MB2 canal. In most cases, it could have also shown whether it was a separate MB2 or joined at the apex. Contemporary endodontic techniques demand an understanding of the nature of the root canal system and exploration of all morphologic possibilities. Any clinician seeing a maxillary first molar that does not have a radiographically treated MB2 should consider it “missed” and a potential source of patient symptoms. If you are unsure of the canal anatomy, referral for better imaging studies is indicated. Such studies are now affordable and easily accessible at most endodontic offices.

Dr. Robert Kaufmann
Winnipeg, Manitoba


  1. Shackleton, T. Failure of root canal treatment misdiagnosed as neuropathic pain: case report. J Can Dent Assoc. 2013;79:d94.

  2. Stropko JJ. Canal morphology of maxillary molars: clinical observations of canal configurations. J Endod. 1999 Jun;25(6):446-50.

Response from the Author

Cite this reply as: J Can Dent Assoc 2014;80:e29

Dr. Kaufmann makes several good points in his comment to my article, to which I would add the following responses:

  1. He finds it difficult to believe that 2 endodontists missed an MB2. I too found it odd that 2 endodontists did not want to treat her tooth, and I agree that the 3 filled canals should have been a red flag. Nevertheless, this is what the patient reported to me. I did not challenge her on this as she had been in pain and distress for some 5 years and came to me for help, not to be cross-examined.

  2. Dr. Kaufmann also asks about conventional preoperative radiographic images. I cannot say what other clinicians did or did not do. I can only relate what I did, which was to take several films, one of which was of diagnostic quality and was reproduced in the article. I have no idea what other images or films other clinicians took. I do know, however, that this patient was in pain and that obtaining that radiograph was very difficult. After the examination and a discussion with the patient, we decided to proceed with non-surgical retreatment—hence the limited value of obtaining additional films. I suggested referring her to an oral and maxillofacial radiologist for a CBCT, but two issues militated against it: 1) she could not afford it; 2) CBCT and direct visualization with a surgical microscope offer the same result.1

  3. Dr. Kaufmann asserts that the use of the “odour test” is unscientific. I agree. However, this was only one observation that supplemented other more important pieces of evidence of infection, including an observable MB2 canal that had been missed, previously treated canals that were contaminated, and 5 years of pain. Nevertheless, I did detect an odour when I opened up the MB2 canal.2

  4. Dr. Kaufmann takes issue with me having prescribed clindamycin after treatment. Judicious prescription of antibiotics is indeed necessary to control the evolution of resistant strains and avoid adverse reactions. But personalized patient care also needs to be taken into account. During her consultation appointment, the patient requested an antibiotic prescription, which I declined because there was no supporting evidence at the time. Rather, I explained that the best course of action in her case was to access the tooth, look for an untreated canal or crack/fracture, and proceed accordingly. During her treatment appointment, she was increasingly distraught and described feeling a general malaise, irritability and fatigue that had been going on for several days since our consultation appointment. Because of these factors—along with the untreated canal, contaminated treated canals and history of pain—I decided to prescribe clindamycin after having reviewed her medical history and thoroughly explained the risks and advantages of using antibiotics. Although her symptoms may have been caused by something other than an infection, prescribing the antibiotic was, in my view, the safest and most prudent course of action under the circumstances.

I will refrain from commenting about the legal implications of a hypothetical situation where a patient experiences an adverse reaction to an antibiotic (which did not occur). I will say, however, that there are legal consequences to a different hypothetical situation, one where a patient experiences a serious bacteremia or flare-up under circumstances in which a clinician could have, but did not, prescribe antibiotics.3

Dr. Thomas Shackleton


  1. Abuabara A, Baratto-Filho F, Aguiar Anele J, Leonardi DP, Sousa-Neto MD. Efficacy of clinical and radiological methods to identify second mesiobuccal canals in maxillary first molars. Acta Odontol Scand. 2013 Jan;71(1):205-9. doi 10.3109/00016357.2011.654262. Epub 2012 Feb 9.
  2. Yamada Y, Takahashi Y, Konishi K, Katsuumi I. Association of odor from infected root canal analyzed by an electronic nose with isolated bacteria. J Endod. 2007 Sep;33(9):1106-9.
  3. Longman LP, Preston AJ, Martin MV, Wilson NH. Endodontics in the adult patient: the role of antibiotics. J Dent. 2000 Nov;28(8):539-48.