Resorption is always a confusing topic.  What causes internal resorption?  Since there are so many kinds of resorption, how do I tell them apart?  What the heck is it, anyway? And what is the treatment for it?  

These are the questions I get all the time. Quite frankly, I don’t feel that dental school covered this enough (or maybe I didn’t pay attention). If you’re anything like me, a little review might be helpful. 


What Causes Resorption

The first thing you have to know is that resorption needs two things to occur:  INJURY and STIMULATION.  Usually, the injury is in the form of trauma.  Looking at the following case, you can probably assume that there was some trauma in the past since she is missing tooth #9.  

How Does This Happen?

During the injury, the protective layer around the tooth gets injured. Our teeth have an unmineralized matrix layer around them as a form of protection.  When that layer is unmineralized, the surrounding cells cannot infiltrate in and damage the tooth.  However, once there is damage to that layer from trauma, the underlying mineralized surface like dentin or cementum gets exposed. This allows our body’s cells to now infiltrate that area and create resorptive damage.  

After the injury, stimulation — usually from the invading bacteria — keeps the process of resorption going.  

Questions I Ask When I See Resorption

When I see an area of resorption, I always want to know:

  1.  What type of resorption is it (external or internal)?
  2.  Where is the resorption located (buccal, lingual, mesial or distal)?
  3.  Does the resorption perforate the tooth?

Asking these questions allows me to develop my treatment plan. (i.e. Is the tooth restorable? Can I heal this with just a root canal?  Or do I also need to do some surgical intervention?)


Using the CBCT to Assess

In order to make these assessments and answer these questions, I like to use my cone beam to help me because it just makes it that much more predictable. Even when I look back at the preoperative image, I can’t tell if the resorptive defect in this particular case has perforated through the buccal or the lingual. But the CBCT shows me with precision that this defect is completely confined within the root.  It also confirms for me that this is a true internal resorption defect, and that it’s located directly in the midroot.   

What’s the clinical significance here? Well, internal resorption is pulpally derived — the clastic cells are coming from the pulp. This type of resorption requires a vital tooth. So what do you do? What causes internal resorption? YOU HAVE TO GET THAT PULP OUT!


Gutta Percha & Obturation

Take a look at the coronal and axial CBCT images below. You can see how clearly defined the borders of the resorptive defect are.  

Since there is no perforation of the root, I don’t have to change how I obturate at all. In fact, I can just use plain old gutta percha.  

However, a single cone technique probably won’t work here — you will have to use a warm vertical condensation technique instead.  


If There’s a Perforation

When there is a perforation, I will usually obturate the tooth with MTA because I believe it will create a better seal.  When there is a perforation of the root,  just doing the root canal may not be enough in some cases.  The root will have to be sealed in order to prevent any further bacterial leakage down the road.  This could also mean that a surgical repair of the defect is necessary, too.  Fortunately, in this case, it wasn’t needed.  


After Determining What Causes Internal Resorption

I’d like to walk you through how I handled this specific case after answering the questions about what causes internal resorption, where it’s located, etc. 

After I accessed it, I obtained my working length.  (I wanted to confirm that I was past the resorptive area with my file. This is sometimes an area that your files can have a hard time passing through, so it’s a good idea to get confirmation with a radiograph.)

Successfully Treating All the Affected Areas in Internal Resorption

Since I feel that resorption can be a little tricky (and I want to make sure that I treat all the affected areas), I medicated the tooth with calcium hydroxide.  My calcium hydroxide did not go all the way to the apex, and that’s okay.  What’s important is that it did dress the walls of the resorption defect.

After a few weeks soaking in the medication, I obturated the tooth. 

Four years later, that tooth is holding strong!

Resorption is something that we see quite a bit in my practice, but they all get referred from my referring dentists.  Even though you may not be the one treating the patient, you still need a deep understanding of what the process is.  Your patients trust you, and they will definitely ask you questions about what is happening inside their tooth. They expect you to have answers, starting with what causes internal resorption, and ending with an understanding of what it will take to treat it. 

This is a topic that I tackle really hard in E-School because I’ve found that the attention this subject gets in dental school is just not sufficient. If you’d like to know more about the ins and outs of treating resorption, sign up here to get on our E-School waitlist. Enrollment opens soon!

Additionally, I frequently post “tooth stories” that serve as examples of different endo situations you might encounter, along with how to treat them, on Facebook, Linked In, and Instagram. Let’s connect!


– Sonia