An Extremely Challenging Root Anomaly: Radix Entomolaris

Terry Pannkuk, DDS, MScD Instructional, Clinical Endodontic Technique Instruction, Diagnosis, Complications: Advanced Management


Patient: 70 year-old male with unremarkable medical history

Chief Complaint: Intermittent pain localized to the mandibular left posterior jaw area noted within the previous few months.

Dental History: Large periapical radiolucency (mandibular left first molar) noted on a radiograph taken by the patient’s prosthodontist. The mandibular left first molar (tooth #19) had been restored with a zirconium crown within the past 5 years.

Significant Findings:
Clinical examination revealed localized palpation sensitivity on the buccal alveolar mucosa opposite the roots of #19. The patient responded negatively to cold thermal (ice) testing. The periapical radiograph revealed large periapical radiolucencies over the mesial and distal roots of #19.

Pulp and Periradicular Diagnosis: Necrotic pulp with a symptomatic periapical abscess (#19)

Treatment Prognosis: Good (#19)

Treatment Plan: Nonsurgical root canal treatment (#19)

Special Considerations of Performed Treatment:
Radix Entomolaris is a molar anatomic variation used to describe an additional root located in a distolingual position. The term was first mentioned by Carabelli in 1844 and more recently the diverse forms were classified by Song et al (2010) based on morphologic characteristics evaluated from CBCT scan observations:
Type 1-No Curvature

Type 2-Curvature in the coronal third and straight
continuation to the apex

Type 3-Curvature in the coronal third and additional buccal curvature from the middle third to the apical third of the root

Small type-Root length less than half that of the distobuccal root

Conical type-Cone-shaped extension with no root canal
The tooth presented was a very challenging small Type 2.

The anomalous root was not obvious from the initial radiologic exam (Figures 1 and 2). Initial access revealed a distolingual canal orifice in an extreme lingual position (Figure 3). The distobuccal, mesiobuccal, and mesiolingual root canal systems were cleaned, shaped, filled with calcium hydroxide and the access was filled with a Cavit temporary filling without a spacer (Figure 4). A limited field CBCT scan was take which revealed the anomalous radix entomolaris root morphology (Figures 5 and 6). It was suspected that the root may not be treatable so the alternate option was to perform a root amputation which minor lingual crown lengthening.

The second visit was dedicated to just finding, cleaning, shaping, and filling the distolingual (radix) root with calcium hydroxide (Figure 7). The root canal system was negotiated by tedious passive recapitulation with a series of hand files with minimal use of rotary files. Constant flushing with 8.25% sodium hypochlorite was performed with periodic irrigation with small quantities of 90% trichloroacetic acid which prevented debris blockage. The small associated periapical radiolucency of the radix root suggested there was patent canal space and that it needed to be treated.

On the third visit all root canal systems were obturated with gutta percha and Kerr sealer via the vertical compaction of warmed gutta percha technique (Figures 8, 9, 10, and 11). The access was restored with a resin bonded composite and the patient was scheduled for a recall examination in one year.

Key Learning Points:

  1. Anomalous root anatomy should always be considered. Expect the unexpected. If unusual anatomy is suspected preoperatively then a CBCT scan should be taken to understand the potential complexities before starting treatment.

  2. Prepare the patient for the possibility of more appointments than anticipated. If you start root canal treatment and the preoperative radiograph fails to show a complicated anomaly, then more time will be required to perform treatment.
  3. A mid-treatment CBCT scan should be taken if the root anatomy becomes confusing. There is a good case to be made for taking a CBCT scan before starting any root canal treatment but some patients are concerned about radiation and the additional expense. It is most important to be sure you understand the root anatomy with clarity if you choose not to take a CBCT scan. It should be considered the standard of care to have easy access and availability to CBCT scanning if performing root canal treatment.
  4. Definitive quality root canal treatment requires time and patience without rushing. Appointment scheduling should allow for flexible time needed to treat challenging cases. Unusually challenging cases should be scheduled to be open-ended without the presence of a subsequent patient creating anxiety and the impulse to rush.
  5. Look for creative alternate options if treatment objectives cannot be satisfactorily met. In this example, the alternate option of amputating the distolingual root provided a sense of peace and calm that a back-up option could still lead to saving the tooth.

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Commenting Guidelines Please make scholarly cited references or expert opinions suitable for publication. The comments can either be "pro" or "con" with references to the treatment philosophy. We encourage objectivity and detailed demonstration of knowledge/literature.
Mohammad Mortazavi commented 1 year ago.

Dear Terry,very interesting case,could you explain the files sequences and final taper that you performed in radix root.

Terrell Pannkuk commented 1 year ago.

Hi Mohammad, Herb Schilder always taught us to not think in terms of mechanical end points and to simply respect the existing anatomy fully understanding the limitations imposed by curvatures, root width, access angles, patient behavioral constraints, and instrument design/tolerances. He stated these things in more simple terms like "passive cleaning and shaping" and "slip sliding" which others have restated in terms like "watch-winding" etc. The main point is don't force a file into delicate anatomy. I currently have a patented solution that removes calcific debris and unblocks canals. Getting blocked out was of great concern in this case because once a ledge is created into a severe curve, it's nearly impossible to smooth it out and redirect along the natural apical path to patency. The moment I saw the extreme lingual angle of the DL orifice after extending the access the first visit, I knew I was in for a wild ride the rest of the way. I simply closed up with CH knowing I really needed a CBCT. If I had tried to negotiate that canal the first visit after tiring the patient out cleaning and shaping the DB, MB, and ML, it would have been a disaster. Now to finally answer your question in detail. I had not opened into the DL orifice at all the first visit but had located where it was. On the second visit I removed the temporary filling (Cavit) which I always place with no spacer. I next removed the CH paste. My solution dissolves CH very efficiently we are currently performing research to show how efficiently it removes CH compared to other commonly used endodontic irrigants. I constantly rinse with 8.25% NaOCl keeping the pulp chamber flooded. I entered the DL orifice with a straight 21mm long .06 K-file (Schwed), constantly flushing with 17% EDTA, and then my experimental solution. I next placed a 21mm .08 K-file, then .10 K-file, flooding with irrigant after each file to prevent debris build-up. Each time the files slip a little deeper. This is what Schilder called multiple recapitulations and "slip sliding". It is difficult to precurve a .06 and .08 file without crushing the flutes so I tend to only precurve the .10 and larger files on these difficult cases. The key is to prevent debris build up; so constantly irrigate and repeat the sequence with small files never forcing a larger file until it slips and slides passively. I never felt comfortable placing a rotary file in the radix root so I did not use any rotaries on it and simply took my time repeating passive recapitulations with a small series of K-files until I could fit a fine gp cone to the working length. It approximated a .06 taper but was probably more like a .05 taper prep. I placed a .06 Greater Taper hand file and was slightly short (maybe 1-2mm) when I completed the final canal prep. I certainly didn't achieve the ideal 5 waves of compaction when I performed the vertical compaction of warmed gutta percha technique on that root, but the amount of time I spent recapitulating and constantly flooding the root canal space with NaOCl likely achieved clinical debridement goals before filling. I place most cores immediately on my cases and certainly did on this one! I hope this description answers your question adequately.

Mohammad Mortazavi commented 1 year ago.

Hi,Terry thank you so much for your reply,your description was so impressive and helpful.

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