Steven Lipner

ILE SEPARATION can be one of the most frustrating—and even fear-provoking—aspects of performing root canal therapy. If a file fragment prevents the practitioner from adequately debriding and sealing the canal space, the case will be more likely to fail, resulting in the loss of the tooth. File retrieval is possible when the file can be visualized through a microscope. However, the retrieval often necessitates an excessive removal of root dentin, rendering the tooth more prone to vertical root fracture. An alternative to retrieval of a separated file does exist. This alternative method consists of using a file or reamer to negotiate around the fragment to the canal terminus. The canal is cleaned and shaped, and the separated file is then “entombed” within the obturant. Note that although the separated file remains in the canal, the objectives of root canal therapy are nevertheless accomplished. That is, the canal is debrided and sealed to the apical constriction. Of course, it would be preferable to retrieve the instrument if it could be accomplished with minimal dentin removal and the resultant weakening of the root. All invasive procedures carry with them benefits as well as risks that must be carefully weighed before proceeding with treatment.
    A patient presented to the office stating that she needed to have a root canal completed. The referral card stated that a calcification had prevented the dentist’s negotiating to the apex. After taking a PA, a 2 mm radio opaque fragment was noted on the radiograph (Figures 1 and 2).

Figure 1	Figure 2

    Upon gaining access to the canals under a surgical microscope, the file was visible in the palatal canal. Though the file was visible, I was unable to dislodge it using ultrasonics. I proceeded to take a number 6 reamer and placed a 45 degree bend at the tip. When attempting to negotiate past an obstruction, the most critical element in achieving success is patience. Any attempt to force the reamer apically will simply result in mutilating the tip of the instrument. This technique is dependent upon a light touch, as one must employ tactile perception to detect a slight “catch.” Slowly, gradually, I could feel the instrument progressing apically until I achieved patency.
    The master cone radiograph revealed that both the buccal and palatal gutta percha cones were placed to the working length (Figure 3).
    The canals were then obturated (Figure 4).

Figure 3	Figure 4

    The next case concerns a patient who self–referred to the practice. His dentist had initiated root canal therapy on tooth number 30. After two sessions, the patient remained in pain, and did not want to return to the dentist who had treated him. Figure 5 is the radiograph that was taken when the patient initially presented to the office.

Figure 5	Figure 6

    Tooth number 30 had two retained instrument fragments (Figure 6). There was a separated file in the distobuccal canal, and a separated Lentulo spiral in the distolingual canal. I was able to visualize the Lentulo spiral through the microscope and removed it with ultrasonics. The file, on the other hand, had separated around a sharp buccal curvature, and I was not able to retrieve it. I was, however, able to bypass it with reamers, evident by the puff of sealer on the distobuccal root in Figure 7.

Figure 7

    I will post follow-up radiographs to both of these cases in six months..
 

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