I Take Things Out; I Put Things In! (The Art of the Retreat)

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Here’s something to chew on. Believe it or not, some root canal therapy fails. I know, I know, how can that be? Well it happens, probably five to six percent of the time. Easy for a practitioner to understand, but always disappointing to the patient and incredibly frustrating to the guy who did it. You get a patient back on a six-month recall with a new PAR or a patient continually presents with symptoms after you did the treatment and you wonder what went wrong, and what do you do?

There are many reasons why endodontic therapy may fail even though you did everything right and the final film looks as if it was taken from an endodontic textbook. Lateral canals in the apical third are a biggie! If not enough irrigation is used in the proper manner with enough agitation in the canal, there may be enough organic matter left in there to break down and feed a chronic infection. Thus, proper irrigation with 2.5 percent NaOCl to dissolve organic tissue and EDTA for the removal of the biological smear layer to open lateral canals, dentinal tubules, and apical deltas is a paramount detail not to be skipped or shortcut.

I know this next question sounds a bit intuitive, but one must ask oneself, “Did I get all the canals?” If in doubt, a CT scan becomes an invaluable tool to make sure that all the canals are identified and instrumented. This is obviously a great diagnostic tool for missed MB2s in maxillary molars, a typical cause of failure.

Now, of course there is the obvious: inadequately instrumented and obturated root canal. Whether it is gutta percha or silver points, if it is short of the apex and the tooth develops a periapical area or becomes symptomatic, there are only three choices. The most aggressive would obviously be to extract and restore. Apicoectomy is also an alternative when retreatment is not advisable. Did I just mention retreatment? The research shows that if you can disassemble and retreat, this is the treatment of choice. Better to identify and re-clean all the canals if possible rather than apically seal in a surgical procedure. In the case of breaking down silver points, it is hard to retroprep the root end, and ultimately you are back sealing a contaminated canal; if the apical seal leaks, the case may be doomed to failure.

Thus disassembly and retreatment, which includes post removal if indicated, would be the treatment of choice. So, without any further ado, I present a silver point retreat.

The patient presented with lower molar symptoms related to a breaking down RCT obturated with silver points in the mesial roots and gutta percha in the distal canal short of the apex. The decision was made to retreat. Access was gained, and the heads of the points were exposed. Now sometimes they come out easy and sometimes they come out hard! Fortunately, I was able to work an .06 file down next to the points and expand the canal. I irrigated copiously with EDTA, and I used a Hedstrom file to engage the point and pull coronally to dislodge it and remove it. Using some Endosol to dissolve the gutta-percha, it too was removed. Measurement was obtained in all canals with an apex locator and confirmed by radiograph. The canals were instrumented and obturated, and the patient remained asymptomatic.

Thus sometimes it’s better to take the effort to retreat than to kneejerk to extraction or surgical intervention. See you next issue.

July - September 2011

Figure 1
FIGURE 1: Pre-op.
Figure 2
FIGURE 2: Distal measurement.
Figure 3
FIGURE 3: Mesial measurement.
Figure 4
FIGURE 4: Final.