How to treat a canal with broken instruments?

How to treat a canal with broken instruments?

Dr Ammar Eid
MSc.  Endodontic & Operative Dentistry (Damascus University)

There are basically three possible approaches that may be encountered when treating these cases: (I) Retrieval, (II) Bypass and sealing the fragment within the root canal space, (III) True blockage.

Factors influencing broken instrument removal success of retrieval depends on the canal anatomy, what type of metal the piece is made out of (stainless steel files tend to be easier to remove), the location in the canal of the fragment, the plane in which the canal curves, the length of the separated fragment, and the diameter of the canal itself. In general, if one third of the overall length of an obstruction can be exposed, it can usually be removed.
Instruments that lie in the straightaway portions of a canal can typically be removed. More challenging are separated instruments that lie partially around canal curvatures, but these can often be removed if straight-line access can be established to their most coronal extents. If the broken instrument segment is apical to the curvature of the canal and safe access cannot be accomplished, then removal is usually not possible.
Techniques for Broken Instrument Removal
Prior to commencing retrieval efforts, special attention is directed toward preoperative radiographs and working films to better appreciate the thickness of the dentinal walls. Coronal access is the first step in the removal of broken instruments, where straight-line access to all canal orifices should be created, and special attention should be directed toward flaring the axial wall that approximates the canal holding the broken instrument.
Radicular access is the second step required in the successful removal of a broken instrument. Hand files are used serially small to large, coronal to the obstruction, to create sufficient space to safely introduce GG drills. They are used like “brushes” to create a smooth-flowing funnel that is largest at the orifice and narrowest at the obstruction.
When the canal, coronal to fractured instrument, has been optimally shaped, then bypass techniques may be employed to remove a broken file segment. Prior to performing any radicular removal techniques, it is wise to place cotton pellets over other exposed orifices, if present, to prevent the nuisance re-entry of the fragment into another canal system. In combination with lubricants, a precurved no.10 stainless file is used to bypass the fractured instrument. If this is successful, Headstrom files are used to try to grasp and remove the segment. Then the canal is cleaned, shaped and obturated to its new working length.

On occasions, the clinician may create excellent coronal and radicular accesses, bypass the fractured instrument, but could not retrieve the fractured instrument. In this case, the canal is cleaned and shaped, and the segment is incorporated into the obturation.

If the fractured instrument cannot be bypassed, then microsonic techniques may be employed to remove a broken file segment. Dental microscope, which allows clinicians to visualize most broken instruments, and ultrasonic instrumentation have dramatically improved the potential and safety of removing broken instruments.

Attempting to remove a fragment without adequate visualization highly risks perforation, as root curvatures can easily mislead the clinician to remove dentin where it will have little benefit toward file removal.
An appropriately sized ultrasonic instrument is selected, such that its length will reach the broken obstruction and its diameter will passively fit into the previously shaped canal. The tip of this ultrasonically selected instrument is placed in intimate contact against the obstruction and typically activated within the lower power settings. The selected instrument is moved lightly in a counter clockwise direction around the obstruction. This ultrasonic action trephines, sands away dentin, and exposes the coronal few millimeters of the obstruction. Typically, during ultrasonic use the obstruction begins to loosen, unwind, and then spin. Gently wedging the energized tip between the tapered file and the canal wall often causes the broken instrument to abruptly “jump out” of the canal

True blockage also does not mean automatic failure. If the bulk of the canal space has been soaking in full strength sodium hypochlorite, and the critical concentration of bacterial contaminants within the canal are sufficiently reduced, the body may heal around this root as well.

Case Report:

22 year old male was reffered to our dental center with two fractured files in tooth 47 the long fragment is in the MB canal and the short fragment is in the distal canal.

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The broken files were bypassed and the canals where treated with Revo-S system with 5.25% NaOCl for shaping and cleaning EDTA 17% as the final rinse,
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The obturation technique was: warm vertical condensation (WVC) System B. and Obtura for the back fill.
ADSEAL sealer.

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Post obturation

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Final restoration, waiting for recall

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