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.
-Sonia
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Love the case ! Recently I had a teen with an elbow trauma on the lower anteriores which resulted into an alveolar ridge fracture – after fracture immobilization, teeth are vital at 3 weeks. Lucky patient. Monitoring is important.
Thank you Dr. Sonia for making a difference in our profession !
Thank you Delia for following, and giving teeth a chance!
-Sonia
This was really helpful.I have a similar case of trauma,it would be nice if we could discuss our case with xrays in your platform.Your blogs arehelping me.
Thank you Roma – I’m so glad that you’re learning from my free resources and blogs. I am developing E-School as the next level, with focused endo education, and also community “office hours” to discuss cases. If you’re on the interest list we will email you an update soon about the launch. It is in beta testing right now, and I’m excited to launch it in 2019!
-Sonia
Nice topic!!…Everytime i learn something new from your case series.And i found it great that you take time and effort to prepare these topics.
But dr could you tell me how come a periapical pathosis develop in absence of microbes? Did it possibly enter retrograde??…. or through some other means…
Thank you.
Great question that I think is still up for debate. In my opinion, if there is a periapical lesion then there must be microbes. So, perhaps there are microcracks that we cannot see that allowed for bacteria to enter the pulp. But, we cannot completely deny the possibility for a retrograde infection. Unfortunately, I don’t think we have the exact answer to this question.
Is PCO a synonym for sclerosis?
That is a good question. I think that there is a small difference in nomenclature here. In my opinion, PCO is usually a result of trauma while pulpal sclerosis is usually a result of aging. So, although in both instances the canals are calcifying, the reasons for which they are calcifying are different. I am sure that there are varying opinions on this topic.
I just want to mention that since i started seeing your blog three months ago and use the c files i am able to do more difficult cases, i really enjoy learning from you!
Thank you!!
Yay Alberto! So glad you’ve found the file that works for YOU!
-Sonia
Dear Dr Sonia,
Very well managed case. Doctor, can you please tell me the sequence of instruments and techniques that you used to gain patency? And how do you make sure you stay centralized within the root and prevent going more labially or lingually?
I have had few such cases, and have been lucky to gain patency. But some cases have complete obliteration all the way to mid root and apically. This answer of yours will help to manage challenging cases. Thanks in advance.
Hi there!! I use C files that help me get patent. But, many times I am going back and forth between hand files and rotary files and using some EDTA. It takes time and patience. Sometimes it even takes multiple visits. You can’t give up especially if there is a lesion. If there is a lesion, there is a canal, you just have to negotiate it properly. As for staying centered in the canal, the rotary will do that for me, I am not worried about that. I hope this helps.
-Sonia
Good Day Mam.On seeing the Radiography it revealed it was a tougher case but You have excellently managed the case…
What was the final size of the preparation for this case Mam.?
Hi and thank you for your comment. Since this was a very calcified case, I took it to a 30/.04 as my final preparation.
Lovely and conceptual presentation
Thank you Abinash!
-Sonia