Internal Resorption Explained + Treatment Guide

A patient comes into your practice, and as you’re reviewing their imaging, you notice that there is resorption happening. Resorption is pretty damn confusing, because there are so many types, and the causes and treatments can vary from patient to patient, and from tooth to tooth. Is it external resorption or internal resorption? What do you do once you figure that out?

Quite frankly, I don’t feel that dental school covers the topic of resorption to the full extent it really ought to. If you’re anything like me, you know that continuing education is the key to being a confident clinician. A little review is always helpful. So, let’s dive into a tooth story to illustrate the ins and outs of a real case.

What causes resorption in teeth?

Resorption of any type needs two things to occur: Injury and Stimulation.

Often, the injury is in the form of trauma, but not always. In the tooth storyI’m sharing with you today, the patient is missing tooth #9. To me, this suggests that she very well may have experienced some form of trauma in the past.

Trauma can cause resorption like this: Our teeth have an unmineralized matrix layer around and within them as a form of protection. When that layer is unmineralized, the surrounding cells cannot infiltrate in and damage the tooth. 

During the injury, however, the protective layer around or within the tooth gets hurt. 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.  

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

1.  What type of resorption is it (external resorption or internal resorption)?
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 because it helps me evaluate:

• Whether the tooth is restorable.
• Whether I can heal it with just a root canal.
• Whether I also need to do some surgical intervention.

Using the CBCT to assess resorption

I like to use my cone beam to help me make these assessments and answer these questions because it makes everything 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 and obturation in internal resorption cases

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.  

What happens if there’s a perforation in a case of internal resorption?

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 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 internal resorption can be a little tricky, and I always want to make sure I’m treating all the affected areas, I chose to medicate 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!

I see resorption of teeth quite a bit in my endodontic specialty practice, but the patients all get referred to me from dentists.

If you’re a general dentist, even though you might ultimately not be the person to treat the patient, you still can be served (and you can serve your patient!) by having a deeper understanding of the process, diagnosis, and treatment.

After all, your patients trust you, have a relationship with you, and they will definitely have questions about what’s going on with 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 within my award-winning endodontic CE program, E-School: Everyday Endo Made Easy, 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, enroll in E-School now.

– Sonia