Case Study: Hand Files Are the Heroes in this Complex Endodontic Retreatment

Case Study: Complex Endodontic Retreatment
Wednesday, March 6, 2013

This article describes the clinical retreatment of a complex failed molar root canal treatment, and discusses the treatment planning considerations and uses of hand files required to remove several canal obstructions within the same tooth. Emphasis is placed on risk assessment and the importance of early referral.

The patient was referred for retreatment of tooth #18. The patient, a 64-year-old female, presented with a history of recent pain localized to #18. There was no swelling or pain at the initial visit.

The tooth was asymptomatic to percussion, palpation, and had slight mobility and pocket depths no greater than 4. The soft tissue examination was within normal limits and the bone support adequate to retain the tooth. The medical history was non-contributory. Apical pathology was visible radiographically. A cone beam was not taken of this tooth pre-operatively and if taken, might have shown a previously unseen separated file fragment in the mesial root (Figure 1).

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Figure 1: Tooth #18 as it appeared pre-operatively. Note the two silver cones in the mesial canal and the H file lodged at the apex of the distal root. Unseen in this dimension is a second separated hand file in the middle third of the mesial root.

The procedure, alternatives, risks and patient’s questions were addressed and consent was given to retreat the tooth. After local anesthesia, a rubber dam was placed and access made. Crown removal was planned. All the occlusal porcelain fractured upon access leaving a flat occlusal surface. Given this, the crown was left in place after the needed occlusal dimensions of the access were prepared. The buildup was carefully removed and two silver cones were observed in the orifices of the mesial canals and gutta percha was observed in the distal.

A Mani #8 D Finder designed for use with calcified canals—the equivalent to carbon steel “stiff” hand files—was inserted alongside the silver cones. Multiple insertions of numerous Mani D Finders allowed negotiation alongside the silver cones to create space into which the cones could hopefully be delivered. After the #8 D Finder was negotiated to the apex alongside the silver cones, the #10 was used to do the same.

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Figure 2: The mesial silver cones have been removed as has the H file from the distal apex. The second separated file fragment is now visible in the mesial root. This was an unexpected finding.

Next #15, #20, #25, #30 and #35 Mani H files were used in succession to attempt to grasp the silver cones and provide their coronal displacement. The #35 Mani H file delivered both of the silver cones coronally. Once the image in Figure 2 was taken, the previously unrecognized file fragment was discovered in the mesial root, it was also delivered using a #35 Mani H file.

The gutta percha in the distal canal was removed to the level of the previous file separation, and with ultrasonics, the file was uncovered. Mani #8 and #10 D finders were used to attempt to bypass the file fragment, but these attempts were unsuccessful. Ultrasonic tips were ultimately used to circumferentially remove dentin around the fragment to deliver it coronally (Figure 3).

The canals were shaped with MounceFile Controlled Memory files and obturated with gutta percha via vertical compaction. All treatment was provided under a surgical microscope (Figure 4).

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Figure 3: All file fragments, silver cones and gutta percha removed.

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Figure 4: The final treatment outcome after the canals had been fully prepared.

The treatment of this case illustrates several important clinical principles including the vital importance of early referral. This clinical case can only be successfully managed by a clinician with a microscope who is experienced and properly trained in removal of both silver cones and separated files.

The risk of perforation, canal transportation and other iatrogenic events is very high. For example, in using an ultrasonic tip to remove the distal file fragment, it would be relatively easy to create an apical perforation and/or to over-enlarge the canal in a mesial to distal dimension in order to create straight-line access to the fragment. Recognizing the iatrogenic potential and referring for optimal outcome gave this patient the best chance to retain her tooth on the first attempt.

The clinician never really knows the true feasibility of retreatment in such cases with separated instruments and silver cones until access is made. Once accessed, the clinician can evaluate the tooth for caries, coronal and vertical fractures, and coronal leakage among many possible findings.

Attempting retreatment allows the clinician to fully gauge the probabilities of clinical success. Extracting #18 in this situation without attempting access would have been arbitrary and potentially unnecessary. The prognosis post treatment is good, empirically, 90% or greater for long term healing.

Proper use of hand files in this retreatment makes the difference between removal of the obstructions and not. It was unknown prior to the access how firmly wedged these silver cones were. Use of small Mani D Finders initially to create space alongside the silver cones allowed me the best chance to subsequently get a purchase on them with H files (Figures 5 & 6).

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Figure 5: Mani D Finders.

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Figure 6: Mani H Files.

Had a rotary nickel titanium file or a Gates Glidden drill been inserted alongside the silver cones, it would likely have cut the small silver cone tails below the orifice, making removal ultimately less predictable.

Be it a calcified canal, a curved canal, or a canal with an obstruction like a silver cone, the value of using small stainless steel hand files from smaller to larger in order to slowly negotiate the canal and create space for subsequent instruments cannot be overstated. As a default, starting curved and calcified canals with #6 or #8 K files or D Finders #8 and #10 is a very safe option. Alternatively, arbitrarily using orifice openers without hand file enlargement first can lead to file fracture, canal blockage and transportation, and a host of other iatrogenic outcomes.

This column has described the clinical retreatment of a complex endodontic case. It discussed the treatment planning considerations and uses of hand files required to remove several canal obstructions. Emphasis has been placed on risk assessment and the importance of early referral. I welcome your feedback.

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