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October 2004 – Premolar Retreatment Surprise

Fig. 1

This maxillary first premolar had a history of intraoral swelling and discomfort. The endodontic treatment had been attempted about 5 years previously by the referring dentist, who also supplied images in Fig 1 and Fig 2. The referral also said that there was caries under the pervious restoration and that the tooth had been restored temporarily with a Parapost and core build up. He suspected that the canals had become contaminated, resulting in what appeared to be a lesion of endodontic origin encompassing the palatal root apex.

My examination showed slight percussive sensitivity but no palatal swelling. In planning for the case, I scheduled the typical amount of time that would be required to remove a Parapost and retreat a 2 canal premolar with preciously negotiated canals. It seemed that all that was required was recleaning of the canals and refill.

Fig. 2

I removed the pulp with ultrasonics. It came out fairly easily from the buccal orifice. I located the palatal canal orifice but was surprised that the orifice did display the characteristic amount of gutta percha I would expect from a typically filled canal. In fact, there was NO gutta percha to be seen, even with a scope. That was odd. I negotiated the buccal canal easily with a file but the palatal canal was completely blocked solid. This wasn't just a typical ledge, my hand files appeared to be up against something metallic. ( After many years of doing endo, you have a sense of whether the obstruction is dentin or a file !)

I then explored the buccal canal more carefully and then - VOILA ! The problem became clear. The two canals that had been previously filled were BOTH buccal canals. This was a 3 rooted 3 canal premolar. A file had been previously broken off in the palatal canal ( see arrow fig 3.) This was the reason for the periapical pathology of the palatal root and the patient's symptoms - an untreated palatal canal. I had not seen this initially because I relied on the referral's Preop film. This film covered the palatal canal with the MB canal filling ( Fig.1)

Fig. 3

I obtained working lengths in the buccal canals ( Fig.3) and shifted the shot more mesially to reveal the P canal. I then attempted to bypass the file fragment in the P canal. This was impossible, the file was broken off too tightly in the canal space. I used some Carr ultrasonic tips and eventually pulverized the file with some Titanium tips that allowed access to the deeper parts of the canal without removing too much dentin. The working length file for this canal is visible in Fig 4.

Fig. 4

Fig. 5 shows the cone fits with sealer in place. The 3 canals are now clearly visible.

Fig. 5

Figs 6, 7 & 8 show the final results of the pack with typical Vertical Warm compaction technique. An interesting lateral canal is visible on the distal aspect. The referral requested that a post space be left, which I did in the palatal canal orifice.

Fig. 6 - Mesial shot

Fig. 7

Fig. 8 - Final Fill

Although the case turned out very well, I was a bit disappointed in my lack of preoperative vigilance. In my haste to get at the case, I assumed that the referral film was good enough to give me all the information that I needed. I had forgotten the " Seymour Melnick Rule" ( named after a wonderful Boston U. teacher I had in my Grad school days) - His Rule ? ->Before evaluating a potential case -> TAKE ANOTHER FILM. Another angle ALWAYS reveals something about the tooth that you may have not picked up without a 2nd or third view. If I had taken that initial image on my own, I would have likely seen that unfilled canal with the broken file and would have not been so confused or pressed for time when finishing this "simple" case. This not only has an impact on time required to treat, but it also has potential impact on the prognosis and fee - things that most patients would like to know before you commence treatment.