Inferior Alveolar Nerve – Anatomy Complications in a Root Canal

Some teeth are easy to root canal. Other ones can have you shaking in your boots. There are so many reasons that certain teeth can be tough, but anatomy is a prime suspect. For example, I want to share a case where the roots were close to the inferior alveolar nerve. Anatomy can really complicate things! 

Have you thought about how you could plan your treatment differently when challenges like these come up? Let me walk you through this tooth story and give you a little insight that perhaps will reduce your fear when you take on the next tricky case.

Inferior Alveolar Nerve and Tooth Anatomy – A Tooth Story

From the moment this young man walked into my office, it was pretty obvious that he needed a root canal, since there was so much decay. He had no pain, but his tooth still felt cold and had no lingering pain. The probings were all within normal limits, and he had no pain from biting or percussion. He had some thickening of the periodontal ligament of the distal root. I diagnosed this tooth as Asymptomatic Irreversible Pulpitis and Asymptomatic Apical Periodontitis #31. 

You can check out the preoperative radiographs below.

I don’t like to make assumptions from 2D imaging, Instead, I like to see what I am working with in 3D. 3D imaging gives me reality and not just a superimposition of reality. We really have to see everything from every angle to get the full tooth story.

In this case, my CBCT confirmed my suspicions that I had in 2D. Uh oh: the inferior alveolar nerve anatomy was going to be a challenge because it was was right at the apices of the roots of #31. This is very evident in the sagittal view below.

And even the coronal view of the mesial roots…

And the coronal view of the distal root…

Ok, be honest, would you freak out at this point?

Seeing this, would you take this case on yourself? Or would you refer the case out because you don’t want to deal with the chance of paresthesia on this patient? 

Well, someone needs to treat the patient, and this is just as much of a risk for me as it is for you. So, I want to share with you some of the treatment considerations and pivots that I make during a case like this. 

Treatment Tips for Tough Cases Like This

Working Length

First of all, working length is super important here. I mean, it’s always important–but especially so in a tooth like this one. When you want to be super precise, you may consider taking a working length radiograph, especially if you worry that your apex locator isn’t cooperating.  You can also check out my tips for apex locator accuracy. In this case, I didn’t have to take a working length radiograph, but I wanted to mention it as an option for you, if you are looking for another safety measure. 

Instrumentation

Once you get that working length, you may consider taking your rotary file instrumentation a millimeter short. Hold up! Please be careful how you interpret what I just wrote. I will take my rotary a millimeter short, but I will still instrument to working length and do that last millimeter with a hand file so that I have more control. You can download my Instrumentation Workflow, too, if you don’t already have it handy!

Irrigation

You may even be concerned about irrigating a tooth like this. And I can tell you that not irrigating is way worse than going ahead with irrigation here. Irrigation is a huge part of the disinfection process, and you must still irrigate a tooth like this. So many people are terrified that they are going to extrude their sodium hypochlorite. But as long as you don’t forcefully irrigate and plunge that syringe, you will be just fine, trust me! I even used the GentleWave here, but I didn’t do it without considering those anatomical structures. It’s all about the details and being careful.

Adapt, adapt, adapt

When I see a case like this, I have to learn to be flexible and adapt. I instrumented short of the apex by a few millimeters prior to the GentleWave. Remember, the GentleWave is instrumenting. I also made sure to pick the best GentleWave handpiece for the job; I used the Cleanflow handpiece here specifically because it is a safer handpiece. After I ran the GentleWave, I went back with my rotary to complete the instrumentation. This gave me the shape for my obturation until the final 1 millimeter, and then that last millimeter, I did with some hand filing.

The Outcome on this Tooth Story

For this case of a tooth where the inferior alveolar nerve anatomy was such a consideration, I had to take a totally different approach than my everyday tooth. But that paid off!

With all of that careful work done, I could obturate. I wanted to make sure that I contained all of my filling material within the tooth. This is crucial, my friends! 

So, even though I will be doing warm vertical condensation, I will adapt again. I won’t be pushing so hard on that gutta percha. And guess what? It may give me a void like it did in this case. And that is okay, in my opinion. Safety first!

Let’s take a look at those postoperative radiographs.

This tooth might not be my most gorgeous work, with those voids and bubbles in the obturation. While it’s certainly not winning any beauty contests, that was not the primary goal I wanted to achieve here. My goal was to perfectly disinfect the tooth and prevent parethesia.

And you know what? I achieved that!

I know that this tooth has been cleaned, so the instrumentation is far more important than the obturation in a case like this.

Don’t get too hung up on something that doesn’t matter and stay focused on what will get you and the patient through a tricky procedure.

So, knowing what you know now, would you tackle this tooth? What did you feel you learned from this tooth story? Let me know in the comments!

And don’t forget to grab my instrumentation workflow for free!

– Sonia