Most times when a rotary file breaks in a canal, the fragment is either irretrievable or the risk to remove it is greater than the benefits. This is purely because they mostly break apically, around curves, and the fragment is often no more than 3-4mm in length.

Using ultrasonics to remove a fragment in a situation like that can very easily lead to excessive damage to the apical aspect of the root. Apical surgery is often a more predictable approach if the fragment must be removed. Many times, however, the prognosis of completion of endodontic therapy with the file fragment still lodged in the root (ie. obturation that incorporates the fragment) can lead to a decent prognosis still. It all depends on the presence or absence of preoperative infection within the tooth and the management of the tooth through the whole process.

I have found that when instruments break in canals like this, it often is more a manufacturer’s defect than poor technique.

Here you’ve got a fairly thick file that broke off leaving a long segment in the canal. The canal is fairly straight and the head of the fragment is visible in the coronal aspect of the canal. I was able to trough around the fragment to about 2mm beyond the head of it. The energy from the ultrasonic tip them unscrewed the fragment and it popped loose. Often applying the ultrasonic directly to a fragment will cause the fragment to further fragment, but this piece was thick enough, not around a sharp curve, and visually accessible enough that I was able to retrieve the file and proceed to complete the endo normally.

On the post-op film you can see how close I was to a perforation of the root even though I had good visibility of the fragment through my microscope. Imagine trying to do all of that troughing in the apical third of the root.

Note that this file has radial lands, a larger tip diameter, and a greater than 0.04 taper. It’s probably a GT file.