How to Obturate a Root Canal with Multiple Canals in One Root

I’ll be the first to admit there are a lot of different aspects of endodontics that can be difficult for dentists. Let’s be real, endo is tricky! Some people struggle with access, while others struggle with implementation. Me? I’m a fast obturator, but if I’m being honest, this is the one area where I still feel like I can have a hiccup. No matter how much experience you get under your belt, obturation can still trip you up! If you want to know how to obturate a root canal with more confidence (especially for multi-canal teeth), this post is for you, my friend!

I’m here to help you learn from my learning, so we can make endo easier for all of us. After all, we could all use some solid endo obturation techniques in our lives.

Specifically, I wanted to write about how to obturate different canal configurations when there are multiple canals in one root. And just so you know, this can occur in premolars, in an MB root of a maxillary molar, in either root of a mandibular molar, or even a mandibular anterior tooth! So keep an open mind, and remember that anatomy always plays a role.

Tooth Story: Obturating a Premolar with a Deep Apical Split

Let’s start with a situation where a premolar has a deep apical split. It’s hard to find all the canals in these bad boys, because the second canal usually doesn’t start until you’re halfway down the root. So, you end up losing a lot of light before you see the extra canal. This is a perfect example of a tooth that will require additional magnification, like a microscope. So that’s the first tip I have for you regarding how to obturate a root canal: make sure you have sufficient visibility in there! Get loupes with a minimum magnification of 5x.

Yet even with the operating microscope, a tooth like this can still be a bit of a challenge. So you should ask yourself if this is a tooth you would want to take on in your practice—or refer to the specialist. There’s nothing wrong with doing an honest risk assessment and knowing your limits. In fact, that’s wisdom! 

In this case, my microscope was useful for me, not only for access and instrumenting, but also for obturating. Here’s our first radiograph.

I used the CBCT to take a closer look at the tooth’s anatomy.

The sagittal view shows you the split much like the PA, but you can see the PARL a bit more clearly. The diagnosis here was Necrotic Pulp and Symptomatic Apical Peridontitis #29.

Coronally, the axial view shows only one canal. But then, as we move apically down the root, we can see that the canals actually become C-shaped in nature!

When labeling these canals while working, I would call them mesial and distal canals.

Early in the procedure, you’ll only see one canal coronally. But once you start instrumenting and moving the walls a bit more buccally and lingually, you will start to uncover the second canal. Keep in mind, though, that you really have to look for it; it’s not the easiest thing to spot. You actually want to make sure that you’re staring at two “dots” when you look in that access.

Your instrumentation and obturation have to be so intentional in a case like this. You can’t rely on your tactile sensation as much as you might in other instances. You have to see where you’re placing your files and your gutta percha. Just a little bit of wisdom when it comes to how to obturate a root canal!

Gutta Percha Woes and Some Endo Obturation Techniques

So, let’s assume you found the canals and cleaned and shaped them beautifully. Hooray!

Unfortunately, these canals will still frustrate you when you go to obturate the tooth, because you won’t be able to fit both gutta percha cones in the tooth at the same time. 

Why? Well, your access won’t be wide enough for that. 

So, if you need to fit both cones in at the same time, you’ll need to use a gutta percha that’s a smaller taper (a.k.a. skinnier) than what you used for your instrumentation. So, you’ll keep the same tip size but will drop your taper.

For example, if you used an F1 Protaper Gold file to instrument your canals, that means you shaped the tooth to about a 20/.07, that .07 taper is going to get in your way. So you’ll use a 20/.04 gutta percha (same tip size, but smaller taper) to obturate so you get more clearance.

Most of the time, I’ll tell you to always take your cone fit radiographs with all of your cones in the tooth to reduce radiation, but you may not be able to do that in a case like this, and that’s okay. Use your best judgment and, if needed, do your cone fit shot with one cone in at a time.

You’ll want to obturate your tooth one cone at a time, too.  

At the end of the day, these endo obturation techniques will make your job a lot easier…

Obturation, Step by Step

I did the downpack of one of the canals first. 

Because I can see where—and into which canal—I’ve placed the gutta percha, and then I can see the tip of my instrument during my downpack, I can do this next step with intention and control.

Sometimes, I get some gutta percha that spills over from my first downpack into my second canal and I get a little block out, but I can just take my MAF and run it into the second canal and clear it out so I’m patent once again. Focus on what matters here.

Once the downpack of the first canal is done, I can place my second master cone and do the step again for the second canal.

Then I can backfill both canals, like this.

Just for the record, anytime my canals have two separate portals of exit, I like to obturate one canal at a time. But I normally take my cone fit radiographs with all of the cones in at once.  

Here are a few more examples of this type of canal configuration…

And…

And just for the record, these last two cases were done by two of my E-school students!!

How to Obturate a Root Canal with Joined Canals

Now, it’s possible you might have canals that are joining in a configuration like this, which will require a different approach. This example is courtesy of a former E-School student.

Again, always take your cone fit with all of your cones in the tooth at the same time. But, when you’re doing the actual obturation, you have a few options in a tooth story like this: You can do one cone at a time, or you can place both cones together.

I usually like to look at my CBCT and see where the point of juncture is for the two canals. If the canals are far enough apart from a buccal and lingual direction and they join pretty far apically, you can place both cones in at the same time. The key is to be able to visualize if the tip of your heated element will pull out your cone while you’re downpacking. 

And then I like to downpack the cone that’s joining—a.k.a. the cone that’s not going to working length. When I’m downpacking that cone, I’m essentially melting that cone into the other cone and melting them together. If the entire cone comes out, then there’s no need to re-measure that cone. That’s because it will be stopped by that point of juncture since the cone going to working length is still in the other canal. Now, if both cones come out, then you’ll have to start over.

Another Obturation Strategy for Joined Canals

This is a process and a repeatable workflow… but it might be stressful for you! If so, you can just obturate one cone at a time. However, you must start with the cone that goes to working length and obturate the joining shorter cone second. When you do it this way, there’s a bigger chance that you will get a void at the junction point—just so you can be aware of the pros and cons. My recommendation is to press a bit harder on that part of your gutta percha when you’re doing your backfill to have a better chance of a beautiful obturation.

If you’re doing a single cone technique obturation, then you may not run into these problems or need any special endo obturation techniques. Lucky you!

But you may see this as a frustration if you’re doing warm vertical condensation. Many dentists understand that there’s an art to warm vertical condensation, and that this type of technique will give you a lot of versatility when it comes to filling those canals. It really is such a great method, and it doesn’t have to be scary. In fact, you can learn warm vertical condensation in just a few days with the right training.

I hope this blog helped you feel more confident about how to obturate a root canal, and that you can take these endo obturation techniques and apply them in your practice immediately.

If you aren’t doing warm vertical condensation and wish that you could be, I encourage you to apply to E-School LIVE today. You’ll get tons of practice and feel like a pro in my hands-on, 4-day, live patient CE endo course for dentists!