External Cervical Resorption

external resorption internal bleaching root canal

External Cervical Resorption Treatment options – Also known as Invasive Cervical Root Resorption

External cervical resorption and the subset of extra canal invasive resorption can be detrimental to a tooth. This pages discusses external cervical resorption treatment options and also discusses some general information about external invasive cervical root resorption. The best article I’ve seen is Mavridou from JOE 2016.

What is External Cervical Resorption and external invasive cervical root resorption?

External resorption originates in the PDL and forms an irregular radiolucent area overlying the root canal; the canal outline remains visible and intact. Sometimes external resorption is not easy to diagnose from the radiograph when the canal outline is indistinct. Three types of external resorption are:

  • Inflammatory Resorption
    – Result of trauma, orthodontics, or pulpal necrosis
  • Replacement Resorption
    – Ankylosis
  • Extra Canal Invasive Resorption
    – Variable, may have inflammation and/or replacement

Extra Canal Invasive Resorption (ECIR) ECIR is a clinical term in use since 1998 to describe an uncommon, insidious and often aggressive form of external resorption.

What is the possible causes of Invasive Cervical Root Resorption or External Cervical Resorption

Certainly genetics play a role as individuals and family members that get Invasive Cervical Root Resorption are prone to getting more. Then there is trauma, which can be both physical and possibly viral. It is interesting that von Arx found 100% of sites had the Feline Herpesvirus 1 and that virus causes similar lesions in cats.

External cervical resorption treatment options vary depending on the severity of the situation.

We prefer to monitor cases of ECR if the the location or severity of the lesion is “requiring” extraction. If you can access, then treatment with geristore or similar and possibly TCA for 1-4 minutes to remove tissue fragments. TCA will destroy all tissue so protect areas that are in the vicinity of treatment. A root canal may need to be done depending on severity and pain levels. Intentional replantation is another option for treatment.

External cervical resorption treatment options include root canal and crown if you can save the tooth still
Saving a tooth may require bone recontouring, root canal treatment, and a crown. We like metal margins on the deep areas after minimal localized crown lengthening.

Some of the newer research shows that leaving them alone will likely lead to them refilling with a bone like material to some extent. If that is the case then treatment will only be done when there is an esthetic issue or pain. Blicher and Pryles seem to agree that if extraction is the only option best to just monitor the situation.

Here is another case that we did not see the ECIR until after starting the root canal therapy. In retrospect on our 3D scan we could see if but missed it. We were able to remove the lesion and restore the tooth and thus far have success.

Does external cervical resorption actually cause necrotic pulps?

When we see x-rays of teeth with ECR the tooth will sometimes have an apical radiolucency.  Many times the tooth appears to be in good shape other than the ECR and that leads us to believe the external cervical resorption causes necrosis of pulpal tissue.  However, if one is to accept that trauma is a risk factor for ECR development, one must consider that the trauma is the cause for both the ECR and the necrotic pulp. Hence although the two diagnosis are correlated one may not be causative of the other. Take this case for example.  If #7 was the only tooth with an apical radiolucency then one may assume the ECR is the cause for the necrosis.  However, the fact that #8 also has necrosis as well strongly points to anterior trauma being the probable culprit for both teeth having apical radiolucencies.

We know the pulp defends itself from external cervical resorption lesions with a pericanalar resorption-resistant sheet or PRRS for short.

What is the pericanalar resorption-resistant sheet or PRRS?

Pericanalar resorption-resistant sheet is the name given to the material that forms around the pulp of teeth that have external invasive cervical resorption. The PRRS forms as a protective measure against the resorption and it consists of predentin, dentin, and eventually reparative (bonelike) tissue apposition.  The thickness of PRRS varies and at least some of it eventually turns into reparative bonelike tissue. Below is one of the coolest videos if you are a dental nerd, check out the PRRS running throughout!

Is no treatment for external cervical resorption the best option?

This is my believe and seems to have support in Mavirdou 2016 JOE article when they show the lesions fill in with a bone like material. I think many dentists see something different and, like a surgeon, jump to a surgical intervention.  ECIR often eventually show repair attempts via the formation of osteoid tissue.

external cervical resorption treatmentAnother x-ray from August of 2023

ECIR over 20 years now.

Another case that is stable or improving.

ECIR improvement over the years.

Dentaltown has several nice threads on resorption cases that include the one shown above.

resorption results in this x-ray
If resorption is left alone this can be the radiographic result. The patients often no symptoms and there is no evidence of this clinically.

Heithersay classification and treatment recommendations for Extra Canal Invasive Resorption (ECIR).

I feel the recommendations are overly aggressive in light of Mavirdou article above but those are merely my thoughts and go against the commonly held beliefs in our profession. This an excellent reference that Dr. Herbert put together on the Heithersay classification.

Invasive Cervical Root Resorption, External Cervical Resorption, and External invasive cervical root resorption – Oh My!

Lots of names but all the same biological process and same are synonyms.

Cases with External cervical resorption or internal resorption that I am not treating but monitoring.

External cervical resorption treatment options

ECIR treatment option
Almost 7 year recall on ECIR

Image of molar internal resorption

Is there such a thing as internal resorption?

Some argue that there is not and that some external resorption just looks like internal. Although internal does seem to have resorption just in the pulpal chamber while ECIR stays out of the chamber. Then there is a case like this below that looks like internal resorption but upon filling looks like might be ECIR. Could also be an internal resorption with a large lateral accessory canal too.

Internal resorption with a lateral accessory canal