Don't Bite Off More Than You Can Chew

Doug Kase, D.D.S.

Tales from the Chamber:
Don’t Bite Off More Than You Can Chew

Doug Kase

he purpose of step-back instrumentation during the SET procedure, using both .02 tapered stainless steel as well as NiTi instruments, is to establish the corresponding resistance form of either a fine-medium or medium gutta-percha point with a minimal amount of dentin engagement.
The philosophy underlying this technique is to incorporate more instruments and for each instrument to do less work when widening a canal. in comparison with techniques that use fewer instruments with each file doing more work, this system

reduces chair time
reduces operator stress
decreases the incidence of fractured instruments

The possibility of fractured instruments increases if, as some manufacturers and clinicians advocate, we put the demand on our Ni-Ti files to do more work than they should be doing. This possibility increases even further when increased demand is coupled with high-energy rotary delivery.
    The following case is one that can evoke butterflies in all our stomachs.
    After instrumentation of a central incisor, a .08 file of greater taper was fractured near the apex. The operator felt that the canal was wide enough to skip the .06 GT file and jumped right to the .08 file. The result was the fracture illustrated in Figure 1, below.
    The operator used the surgical microscope to visualize the file. Using a fine ultrasonic Spartan diamond tip, he made a trough around the coronal aspect of the file.
    Then, using a white hollow trephine bur from a Masserann Kit by Micro Mega, he created a tunnel to the top of the GT file. Since the trephine bur cuts counterclockwise, as does the GT file, he reversed the rotation to clockwise and exerted apical pressure to grip the remaining piece of GT file (Figure 2) and rotate it clockwise, coronally out of the canal (Figure 3).
    An alternative method for removal is to aspirate a small amount of cyano-acrolate cement (Crazy Glue) into the lumen of a 20 to 23 gauge needle. Insert the needle to the exposed instrument and engage the coronal aspect of the file. After the instantaneous set, try to rotate the instrument out of the canal.

FIGURE 1: Fractured instrument in the canal.

FIGURE 2: Gripping the remaining piece of GT file with a hollow trephine bur.

FIGURE 3: Rotating the file clockwise out of the canal.

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