External Root Resorption

Hopefully everyone knows that cavities can destroy tooth structure from the crown down. But there are two different types of tooth resorption that can destroy teeth below the bone level, internal and external resorption. Internal resorption is much more rare and usually occurs after some type of injury to the pulp. External resorption of a root (ERR) is a more common phenomenon. Along with being more common, most cases of external resorption are mild and seem to be self limiting. That being said, 10% of patients who present with external resorption do show concerning amounts of progression1. ERR also appears to present between the ages of 21- 30, and more predominantly in females5.

Comparing and Contrasting Internal V. External Resorption:

  1. As noted above, Internal Resorption is much more rare than External Resorption
  2. Resorption occurs in the pulp for Internal and along the PDL and cementum for External
  3. Both are painless unless communication occurs between the dental pulp and alveolus
  4. On radiographs: external has a moth-eaten appearance, internal has a balloon-like appearance
  5. Classical appearance of Internal is a pink tooth, External will only have this appearance if resorption occurs near the cervical region.
  6. In both types of resorption, clastic-like cells are responsible for the destruction
  7. Treatment is similar in that removal of all soft-tissue around destruction, then remineralization.

Factors that may Stimulate External Resorption:

  1. Excessive orthodontic movement, occlusal forces, or dental trauma
  2. Re-implantation of teeth after avulsion
  3. Hyperparathyroidism, Paget’s disease, Tumors, Cysts, or other Hormonal imbalances
  4. Periodontal Treatment, or periodontal grafting
  5. Non-vital bleaching treatment
  6. Idiopathically
  7. And of course, Genetics1,2,3


Obviously the earlier the diagnosis of ERR, the better the potential outcome for the tooth. The pulp usually does not play any role in ERR, so thermal testing has little benefit towards diagnosis as the tooth can still be vital. The best way to catch this problem is radiographically. Using the SLOB method for 2D radiographs or CBCT systems is currently the best way to detect ERR4. It is also important to determine what may have caused the ERR to occur in the first place to help classify and diagnose.


  1. If the ERR appears to be stemming from orthodontic treatment or from pressure from another tooth, removal of the stimulus has proven to terminate the resorption. That being said, if the tooth has become mobile due to the resorption, splinting may be required6.
  2. Pulpal exposure due to the resorption will require Endodontic therapy, then treatment of the resorptive defect will be required7.
  3. After inactivation of the cause(s) of the resorption, it is imperative to remove the granulomatous tissue, clastic cells, and diseased tissue surrounding the defect8. There has been multiple proposed treatments for External Root Resorption:
    • After removal of diseased tissues, chemical mixtures can be used to disinfect the area such as Carnoy’s solution, then application of MTA to the defect has been used to close the defect and provide a seal to the tooth9,10.
    • Similarly, a product called Biodentine has shown positive results when used as a defect sealer using related steps mentioned above11,12.
  4. If the resorption has become too extreme, extraction of the hopeless tooth is an option.


If not caught in the early stages, External Root Resorption can become detrimental to a tooth or teeth. The best way to catch ERR is radiographically, and the earlier the better the outcome for the tooth. There are multiple potential causes of ERR including idiopathically. Regardless of the cause, proper debridement and of defect and sealing the tooth is a requirement. If there is uncertainty on how to treat External Root Resorption, referral to a Periodontist or Endodontist is necessary.

  1. Neville, B. W., Damm, D. D., Allen, C. M., & Chi, A. C. (2016). Oral and maxillofacial pathology (4th ed.). St. Louis, MO: Elsevier.
  2. Trope M. (1997). Cervical root resorption. Journal of the American Dental Association (1939)128 Suppl, 56S–59S. https://doi.org/10.14219/jada.archive.1997.0426
  3. Harrington GW, Natkin E. External re- sorption associated with bleaching of pulpless teeth. J Endod 1979;5:344-7.
  4. da Silveira, H. L., Silveira, H. E., Liedke, G. S., Lermen, C. A., Dos Santos, R. B., & de Figueiredo, J. A. (2007). Diagnostic ability of computed tomography to evaluate external root resorption in vitro. Dento maxillo facial radiology36(7), 393–396. https://doi.org/10.1259/dmfr/13347073
  5. Opacić-Galić, V., & Zivković, S. (2004). Ucestalost eksternih resorpcija na korenu zuba [Frequency of the external resorptions of tooth roots]. Srpski arhiv za celokupno lekarstvo132(5-6), 152–156. https://doi.org/10.2298/sarh0406152o
  6. Heithersay G. S. (2007). Management of tooth resorption. Australian dental journal52(1 Suppl), S105–S121. https://doi.org/10.1111/j.1834-7819.2007.tb00519.x
  7. Fuss, Z., Tsesis, I., & Lin, S. (2003). Root resorption–diagnosis, classification and treatment choices based on stimulation factors. Dental traumatology : official publication of International Association for Dental Traumatology19(4), 175–182. https://doi.org/10.1034/j.1600-
  8. Iglesias-Linares, A., & Hartsfield, J. K., Jr (2017). Cellular and Molecular Pathways Leading to External Root Resorption. Journal of dental research96(2), 145–152. https://doi.org/10.1177/0022034516677539
  9. Gulsahi, A., Gulsahi, K., & Ungor, M. (2007). Invasive cervical resorption: clinical and radiological diagnosis and treatment of 3 cases. Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics103(3), e65–e72. https://doi.org/10.1016/j.tripleo.2006.10.005
  10. Kumar, S. S., Kumar, N. S., Karunakaran, J. V., & Nagendran, S. (2015). Management of invasive cervical resorption in a maxillary central incisor. Journal of pharmacy & bioallied sciences7(Suppl 2), S712–S717. https://doi.org/10.4103/0975-7406.163494
  11. Baranwal A. K. (2016). Management of external invasive cervical resorption of tooth with Biodentine: A case report. Journal of conservative dentistry : JCD19(3), 296–299. https://doi.org/10.4103/0972-0707.181952
  12. Agrawal, V. S., & Kapoor, S. (2020). Management of root canal stenosis and external inflammatory resorption by surgical root reconstruction using biodentine. Journal of conservative dentistry : JCD23(1), 102–106. https://doi.org/10.4103/JCD.JCD_128_20

The Author of this post does not assume any liability for any injury and/or damage to persons or property as a matter of products liability, malpractice, negligence, or otherwise, or from any use or operation of any methods, instructions or ideas contained. The foregoing parties will not be liable for any direct, special, indirect, incidental, consequential, or punitive damages as a result of the reader’s use of this information.

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