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Detecting a Challenging Root Anomaly: Conclusion to Puzzle

Terry Pannkuk, DDS, MScDDiagnostic Puzzles, Instructional, Complications: Advanced Management, Sample Cases, All by Date


Preoperative periapical radiograph (4/16/2015)


Preoperative periapical radiograph (horizontal angle, 4/16/2015)


CBCT frontal plane capture section showing the extreme anomalous form of the radix root entity positioned toward the lingual (4/16/2015)


The CBCT transverse capture section shows another perspective of the radix position toward the lingual aiding in appropriate endodontic access (4/16/2015)


The CBCT transverse saggital capture section shows the traditional periapical radiographic perspective but offers little clue to challenges that might be encountered with endodontic access (4/16/2015)


Clinical access to the distal root canal systems (DL and DB confluent, 5/18/2015)


Note the orifice to the radix anomaly exiting the corner of the distal pulp chamber toward the lingual, 5/18/2015)


Mesial root canal systems cleaned and shaped, 5/18/2015)


Cone fit verification check radiograph (5/18/2015)


Obturation check radiograph (5/18/2015)


Immediate post-treatment radiograph (5/18/2015)


Immediate post-treatment radiograph, additional angle (5/18/2015)

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Patient: 79 year-old male with glaucoma

Chief Complaint: Biting, Chewing Sensitivity on the lower back right jaw area

Dental History: The patient presented with no recent restorations and biting sensitivity localized to the mandibular right first molar (tooth #30) which had a full gold crown placed many years earlier

Significant Findings (tooth #30): The tooth measured a positive response to cold thermal stimulation, severe chewing sensitivity, and moderate percussion sensitivity. The periodontal and all other clinical findings were within normal limits. The radiograph demonstrated a radiopacity at the mesial and distal distal areas of the crown approximating the mesial and distal pulp horns. A THIRD DISTINCT MOLAR ROOT WAS ALSO NOTED

Pulp and Periradicular Diagnosis: Stressed pulp and acute periradicular periodontitis (tooth #30)
Treatment Prognosis: Good

Treatment Plan: Nonsurgical Endodontic Therapy with Fracture Exploration (Tooth #30)

Special Considerations of Performed Treatment:

The advent of limited field CBCT scanning for the dental office has revolutionized dental imaging and noninvasive dental diagnosis. It has created a controversy whether the CBCT scan should be performed on every single patient presenting or a potential need for endodontic treatment or if it should be employed for “special” presenting cases.

This author selectively utilizes CBCT scanning as it can be employed at any time during the treatment process if confusion over the tooth status or root anatomy exists. Often times a pretreatment CBCT scan is not as useful as a later scan when the metal restorations are removed and a radiopaque material can be placed in preliminarily accessed root canal system. Patient concerns over radiation, although scientifically unfounded for most modern microCT machines, sometimes dictate the clinician’s use of a CBCT so it is often best to consider the most useful point in treatment to take it.

In this case the preoperative radiograph demonstrated a rare and very challenging root anatomy variation called the “radix entomolaris”. The “radix”, or third root, is often anomalous, angled, and smaller than the common mesial and distal roots. Extreme care must be taken to avoid perforation. In this case the radix root entity was very narrow, concave, curved, and exited the distolingual aspect of the pulp chamber at the corner almost at a 90 degree angle. The anomalous root anatomy was noted on the initial traditional preoperative radiograph but it was decided to perform initial access and place intracanal calcium hydroxide before taking a CBCT. The CBCT was taken to assess the how safely the radix root canal system could be cleaned and shaped without risking perforation.

Direct line access to the radix was compromised and a narrower gutta percha cone was placed than would have been chosen for a common prepared mandibular molar root canal system. Numerous small precurved hand file recapitulations with copious irrigation was performed to clear the system. The other four root canal systems (ML, MB, DB, DL) were cleaned, shaped, and obturated routinely. Immediately after obturation a bonded resin core was placed (Luxacore/Photobond). No crown-root fracture was found to be present and the patient was scheduled for routine follow-up examination.

Key Learning Points:

  1. CBCT scanning can detect and greatly enhance the management of teeth having unusual root anatomy

  2. A thoughtful decision when to take a CBCT scan prevents unnecessary preoperative scans unlikely to provide a critical option determinant

  3. Failure to take a CBCT scan when one is indicated may lead to mismanagement of challenging cases

  4. CBCT scans are often best taken when the root canal system is filled with a radiopaque marking material like calcium hydroxide, or when all metal restorations are removed to prevent distortion of the image in the cervical region due to beam hardening

  5. The radix entomolaris root variation can occur in mandibular molars and should be recognized and considered as very challenging requiring special endodontic management

Join the discussion

The mesial and distal radiopacities are interesting. Could it be that a direct pulp cap was attempted when the tooth was cut for an extracoronal restoration ? Overtime leakage from margins may have caused bacterial entry and pulp involvement (although crown margins look good here). I would remove the restoration and inspect. Severe chewing sensitivity ?? Cracked tooth ? But with a crown on top ? Very interesting case. Will be waiting for the follow up post.

Looks like a pin retained restoration which is in close proximity to the pulp horns....so when the patient is masticating the wedging effect is transferring load on the pulp horn, which in turn is causing pain. I also suspect VRF because of the pin retained restoration. the hidden truth ll be revealed only after we remove the crown.

It is Radix Entomolaris case...I also suspect the pin retained restoration as mentioned by Dr Harsh Amlani. How the patients feels the sensitivity when the crown is intact? Is there any marginal leakage at the cervical region of the crown? A clinical picture is required. As mentioned,we comes to know the diagnosis once the crown is removed.Eagerly waiting for the upcoming post :) Thanks for sharing an interesting case Dr. Terry.Regards!

I looked at this case late last night, and on the drive into work this morning, I was thinking about it - as - the clinical symptoms are somewhat bizarre and don't add up to cracked tooth. Then, something on the vertical bitewing caught my eye. I think the radix is catching our attention and steering us away from something subtle.

Radiographic Eval: Vertical Bitewing: #30 - Apart from a potential previous direct/indirect pulp cap, I also see what may be a non symmetrical radiolucency which overlays the pulp chamber. From my experience, this may be Invasive Cervical Resorption (ICR). I've had several cases where the clinical findings were normal (probing, BOP, ging inflam), however, as time progressed, the patient experienced an increase in biting sensitivity. (Heithersay 1985/Schwartz 2010). Definitive Diagnosis would be confirmed with a CBCT and if there is a history of trauma/orthodontics. Bilateral ICR lesions are very rare, so comparing the contralateral teeth would most likely reveal very little (can't remember the literature for this one at the moment!)

Diagnosis: Reversible pulpitis (ICR) with symptomatic periradicular periodontitis

Treatment: If minimally invasive, it could be solved with removal of the resorptive lesion, and restoration of the lesion without endodontics. The positive cold test (I"m assuming fleeting vs lingering) may indicate that the pulp is either normal or reversibly inflamed. Endodontics would be initiated once the pulp becomes irrev inflamed or the resorptive lesion invades the pulp chamber.
Prognosis: Good if Heithersay Class 1-2 (minimally - moderately invasive), Class 3-4 questionable to poor (severly invasive).

If ICR is ruled out, then the clinical symptoms are seem to lead me to think of a cracked tooth.

Radiographic Eval: Tooth #30. Coronal cast restoration and I believe that a mesial shift shot relative to the vertical bitewing reveals a radix entomolaris (as Prem Anand J) had mentioned - (I mention the mesial shift to rule out radix paramolaris and where to look during endodontics). I would ask why the patient has an RCT on #31 and if the contralateral teeth have restorations/endodontics for cracked teeth as well. The periapical tissues appear to be normal on all teeth exposed on the PA radiograph (#31/30/29). As well, Krell/Rivera 2006 noted that 20% of teeth undergoing a coronal restoration became necrotic overtime (6 months). It's probably been longer than 6 months for this patient, however, pulp health is on a continuum and we may be seeing the change from pulp health to reversible to irreversible pulpitis in some pulpal regions.

Dx: Tooth #30: Reversible to Irrversible pulpitis secondary to a crack (continuum) - ultimately leading to fracture necrosis (Bermann/Kuttler 2010) + symptomatic (periradicular) apical periodontitis
Treatment: Tooth #30: Endodontic therapy
Prognosis: Questionable. As per usual in cracked tooth cases, methylene blue dye staining of the pulp chamber to discern and document the extent of the crack is necessary. The more apical the crack, the lower the prognosis.. This has to be completed with a microscope.
FU: Every 6 months to evaluate clinically (probing) to see if the crack has started to involve the periodontium and radiographic eval to see if there are any periradicular resorption secondary to a crack.

Sorry for the long post. It's much easier to talk cases like this through! Thanks for the opportunity for a challenge.

Hi am an endodontist in the uk shortly to retire, I have had two upper molars become non vital possibly due to parafunction, When I looked at this case taking account of the patient's age I thought this molar has had "enough" my terminology is age induced pulpal death. I agree a cone beam scan can identify unseen pathology but sadly in the UK scanning technology is not readily available.

Great comments. I posted this case, knowing many would recognize it as an obvious radix entomolaris anomaly. The lingual root happened to look extremely high risk for perforation on the CBCT. There were some distracting issues like the deep bilateral radiopacities, probably previous pulp cap, and suspected crown fracture. The symptoms resolved after the first visit by the second visit one month later. My preference is to place CH for at least a month mainly to insure the symptoms have resolved and initial healing is occurring before completion of treatment. I really appreciate the time spent to provide thoughtful long clinically relevant references.

Terry, I totally agree with you, but having to work without scan facilities,I always ultrasonically "peel" away the pulpal debris to identify the canals, if the distal canal is extrinsically( buccaly) placed then I invariably hunt for the disto lingual canal, It can be time consuming, hence the value of a scan.

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