Lateral canals — they are so easy to forget about as a potential culprit for root canal failure. When teeth don’t act right, we need to think outside of the box. It’s easy to blame a crack or even a missed canal, but what about a lateral canal?  I forget about this little guy all the time and it often stumps me in my diagnosis.

Let me walk you through this case so that I can show you exactly what I am talking about.  Here are the preoperative radiographs…

When I first examined her radiographs, I felt as if tooth #3 should have been the problem. I really liked the way #2 looked on the radiograph, but I was too quick to judge because this patient had pain to percussion on tooth #2.  I was able to diagnose her with a Previously Treated Tooth and Symptomatic Apical Periodontitis #2.  I think we all know by now that in a case like this, I will take a CBCT.  So, here we go…

Even after the CBCT I still felt like the culprit tooth should have been tooth #3.  This axial slice shows me that all the canals appear to have been found and obturated in tooth #2, but there was a potential for a missed MB2 in tooth #3.  So, I was really surprised when I saw that it was #2 that was bothering her, and she was very localized to the percussion test on tooth #2.  So, I looked deeper into the CBCT and found this…

I found this furcation breakdown and I didn’t know what it meant.  Was it a sign of a crack? Was the root canal just recontaminated?  Or was there a separate periodontal issue superimposed onto this root canal?  I was stumped!  Luckily, the patient was highly motivated to save her tooth.  She BEGGED me to retreat the tooth and since we just don’t know sometimes until we try, that’s what we did.

My root canal doesn’t look much different from the preop except for one minor difference — there is a lateral canal radiating from the MB root that leads right into that furcal breakdown.

Now, I need to give a little disclaimer here.  I retreated this tooth with the GentleWave and I don’t think that I would have been able to pick up that anatomy any other way.  I wish I could fast forward a few months to see this thing heal.  And if it does, that will blow my mind and it should blow yours too, because it’s crazy that something so small could have such an effect!  I promise to post the recall in another future post.

So, the moral of the story is that we can’t forget that a tiny little lateral canal into the furcation can also make a tooth appear “cracked”.


Let me show you another case. This patient had no pain, but clearly had a problem.

You can see that the tooth has been previously treated, but there is some furcation breakdown. Once again, the root canal looks fabulous!!

You can see from the bitewing that the tooth was not in occlusion.  So, the idea of a crack was just not in my differential diagnosis.  Now I had to think outside the box.  What else could be wrong?  When I took the CBCT all I could see was this….

A periapical lesion that went into the furcation.  This can be a very typical endodontic lesion, but I know that this would scare most dentists.  This appearance of a PARL is normal to me, but I always want to know “why?” (and I absolutely hate it when it is not obvious).  I let the patient know that I can try to retreat it, but I cannot promise anything.  Luckily, I once again had a motivated patient who wanted to try to save his tooth no matter what.  So we retreated the case.

Again, this root canal does not look any different than the preop besides that little lateral canal.  But, could this canal be the cause for failure? Probably!

My point with this blog is that we need to think outside the box with our diagnosis and consider that these tiny little lateral canals could be the cause of a failing tooth.  So don’t be so quick to extract!  Instead retreat to try to see if you can save a natural tooth.

Again, I can’t wait to fast forward a few months to see how this puppy heals.

Due to what I learned in the previous case, I also retreated this case with the GentleWave.  Many endodontists have not really embraced this technology and it sure is taking me time to get used to it.  What I am witnessing is not “slap in your face” evidence, instead it’s these little things that I am finding as I obturate.  I still think that it is too soon to judge how effective this technology is, and that is why it is just an adjunct for me at this time.  But I do know one thing — it’s irrigating better than my syringe, that’s for sure! I don’t think that I could have made access into this lateral canal with the conventional root canal methods.  But only time will tell and I can’t wait to show you the recall.

Remember: not all “bad” teeth are cracked!

Until then my friends,


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