Patient: Male, 45 years old
Diagnosis: Previously treated and asymptomatic apical periodontitis
The patient had no history of pain, however, upon evaluation his general dentist noticed something suspicious on his x-ray and he was referred to my office. The clinical evaluation was insignificant, there was no pain to temperature or tapping. Thorough discussion with the patient revealed the true dental history of tooth #14.
The patient has had a previous root canal (about 20 years old) and a surgery on the same tooth in 2013. The traditional x-rays (pictured in image #1) were inconclusive, but a dark area over one of the roots was observed. A CBCT was taken in order to determine the whole story prior to treatment.
Image #2 shows the axial slice (it shows 3 filled canals) and it confirms a missed MB2 canal (the 4th canal). Image #3 confirms the presence of active infection even with the absence of symptoms. The dark areas marked by the red areas show areas of bone resorption. This only occurs when there is an infection inside of the tooth.
Once the infection is cleaned out, the bone will regenerate. This is the beauty of root canal therapy.
Image #4 is the coronal image of the CBCT. This image shows that only one canal was found in the MB root and it also shows the presence of a root-end filling material that was placed at the time of apicoectomy. The red arrow in image #4 is pointing to the area where another canal resides, but this area was never cleaned in the original root canal (20 years ago) and the surgery. This is the reason for the root canal failure and the lingering infection, since there is original bacteria in this canal (about 20 years old). Image #5 is a conefit x-ray that shows 4 canals located, cleaned and ready to be filled. In this particular tooth, there are 4 canals about 95% of the time.
FINAL: The final x-rays (two different angles) showing 4 separate canals in a maxillary first molar.
- Find ALL the canals and get to the end of every canal and the root canal will work.
- Even a surgery cannot fix a missed canal, the root canal must be disinfected thoroughly first!!
I think locating the mb2 is very challenging. I have learned to refer upper first molars because of this. Great article.
Nice case. Missed MB2 causing apical disease. What was going on with the other area of apical disease ( palatal root)?
John, it’s possible that there was contamination overall. I am not sure of the disinfection protocol that was used on the initial root canal.
Great case indeed. Accurate diagnosis and treatment.
Thanks for sharing.
And thanks for following my blog!
Nice case. I think CBCT and microscopy have revolutionized our practice. Indeed as to refer to the case treated 20 years ago, it is very probable that the clinician was not using magnification to localize MB2 and thus was unable to completely shape and clean the whole root canal system. Of course, the root end surgery was unable to remedy to the problem too. Thank you for sharing.
Thanks for reading Edmond and supporting the cause — let’s save more teeth!
What a good save finding the MB2! Was the MB2 difficult to locate? It is difficult for me to see the canal on the axial slice and the root looks thin in that area. I imagine a microscope is tremendously helpful in these situations. Under a microscope can you normally see color changes where a calcified canal is, or what do you see that gives you confidence to chase it further without perforating?
Hi again! When I see the MB canal not centered in the root on the CBCT, I am pretty certain there is an MB2. So, I don’t necessarily see the “dot” on the CBCT in the axial slice. The coronal section may sometimes be the slice where you pick it up. Regardless, if it is not centered in the root, I am going to trough for it. The microscope makes it super helpful finding that exact point in which you need to trough to unroof that orifice. And yes, many times I do see the color changes with the microscope. I have loupes too and I cannot see this distinction without the magnification of my scope. Talk soon!
as a post graduate student i find it very difficult to locate MB2 in maxillary and middle mesial canals in mandibular molars.
we cannot use CBCT in our daily practice
i will be highly grateful if you could help me with some anatomical landmarks that indicate the presence of an extra canal.
The MB2 is usually about 2mm lingual to the main MB canal, but it is usually a bit more apical too. Ao you will need to trough apically many times in order to find it and that requires high magnification. It’s the hardest thing in endo if you ask me. Start with some extracted teeth so you can see that trend, I think that will be very helpful for you.
I’m with Meena…even if I find the MB2, it can be extremely difficult and frustrating to clean, shape and obturate, so I let the Endodontist earn their keep by referring ALL molars to them. In a busy practice you have to decide what is best for the patient AND you….I am very thankful for my specialists and these really neat case studies. Keep’em coming!
Thank you Richard! More to come…
Thanks for sharing. Did you remove the root end filling material during the retreatment?
I was patent for sure, but it is hard to tell. I hope that makes sense to you.