This blog is about a case of PCO.  PCO stands for Pulp Canal Obliteration.  What does that mean? Well, PCO is usually a consequence of trauma.  Take a look above at this young girl’s radiograph.

The girl had trauma about 8 years ago when she was hit in the face with a ball, but she brushed it off because she didn’t have any pain — until now.  She presented to my office because tooth #8 was now symptomatic and hurt when she touched it. Her mom told me that they had always gone to the dentist regularly, and this whole time their clinicians had never mentioned that there was a problem with her daughter’s tooth.

Teeth #8 and 9 had no response to cold and only tooth #8 was tender to percussion.  So, I was able to diagnose tooth #8 with a Necrotic Pulp and Symptomatic Apical Periodontitis.  

When you look at the radiographs, you see that both teeth #8 and 9 have no more canal space.  The canal space is completely obliterated as a result of the trauma. See, after trauma like hers, two things can happen, either the pulps can go necrotic or the pulps will obliterate.  In this case, she got the latter.

Sometimes when I take a CBCT it shows me a different story, but in this case her scan confirmed the obliteration. Check it out, this is tooth #8 in the coronal view…

And this is tooth #9 in the coronal view…

You can see that #8 has a PARL, but #9 does not.  And the axial view did not make me feel that this was going to be a slam dunk.  

And neither did the sagittal view…

There were no canals in either of these teeth, but luckily, I only needed to treat #8.  So, I began my conversation with the patient and her mom.

I told them that I could attempt the root canal, but if I could not find a canal or negotiate it to working length, then she would become a candidate for surgery (an apicoectomy).  The patient also had the option to just go straight to the surgery. When there is a lesion like this though, that is not my favorite option since the entire tooth is necrotic, but I would only be treating the last 5-6 mm of the root with surgery.  I just don’t feel like that is a long-term fix.

So, in this case, I went with my gut.  I always believe that if there IS a lesion, then there IS a canal.  And together with the patient, we decided to try the root canal first.  And man am I glad that we did….

I was able to find the canal with an itty bitty 6 file and get to patency.  We all did the happy dance when we saw that file in the canal!! I was able to keep it conservative and finish the case.

And the best part is that there is no more talk about needing a surgery!!

What could we have done to make this case easier?  Taking follow up radiographs after a traumatic incident is #1!!! If you have a patient like this and start to see changes in the canal space, then you can intervene earlier when the canal is bigger and wider and the risk of perforation or file separation is lessened.  

Did you know that in cases of PCO only about 15% of the cases will go necrotic?

It’s kind of neat that in this case, only one of the two teeth with PCO actually went necrotic.  So, in cases like these with PCO you may run into diagnostic dilemmas and you may have to make a decision on what to do.

Do you treat it with a root canal before necrosis or wait for necrosis and possible obliteration?

This is definitely a debate in the endo world since a 15% necrosis rate is small.  So, keep this statistic in mind because it may come in handy one day!  And don’t forget to follow up with your patients regularly for years after any traumatic incident to catch these things early.



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