What is Tooth Resorption and What Causes It?

What is Tooth Resorption and What Causes It?
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What is Tooth Resorption and What Causes It?Clinical Content Reviewed by Dr. Jay Khorsandi, DDS
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Table of Contents

  1. What Is Internal Resorption
  2. Causes of Internal Resorption
  3. External Resorption
  4. Surface Resorption
  5. Inflammatory Resorption
  6. Replacement Resorption
  7. Cervical Resorption
  8. Transient Apical Breakdown
  9. Signs and Symptoms
  10. Tooth Resorption Treatment Options
  11. Root Canal
  12. Calcium Hydroxide Therapy
  13. Extraction
  14. References

Tooth resorption is the gradual loss of dental tissue after injury either to the pulp or the periodontal ligament (the tissue fibers supporting the attachment of your tooth to the adjacent bone).

There are two primary categories of tooth resorption, each identified by where it originates: internal and external. A patient can have either condition or both on the same tooth, at the same time, although internal resorption is rare.

Unless your dentist brings it to your attention during a routine dental exam, you may not know you have tooth resorption. Like most patients, you may not experience any pain or other symptoms as cells gradually eat away at parts of the structure of your tooth.

Resorption can cause cosmetic and functional issues. They include:

  • Unsightly tooth discoloration
  • Chipped teeth
  • Tooth loss
  • Infection

Factors that may predispose you to tooth resorption include:

Most patients with tooth resorption have had injury to tissue within the pulp or periodontal ligament.
Bacterial infection may cause swelling of the gum around the affected tooth.
Studies suggest that certain people may be genetically predisposed to tooth resorption lesions and more severe inflammation than others.
The typically slow, gradual occurrence of this condition allows you to prevent serious tooth damage or loss by getting an early diagnosis and treatment.

What Is Internal Resorption?

Internal tooth resorption has a lower prevalence rate than external resorption and originates in the pulp of the tooth. The pulp is the central part of a tooth and the part that gives it life. It is where blood vessels, connective tissue, nerves and other cells co-mingle to feed and nourish the tooth to keep the tooth healthy and viable.

Resorption here occurs when a specific set of cells, called osteoclasts, cause the breakdown (demineralization) of dental tissue in the pulp (dentin). The dentin comprises calcified tissue surrounded by protective layers in a healthy tooth. When resorption occurs, it damages this protection, exposing the dentin to breakdown.

Types of internal tooth resorption include:

Inflammation due to bacterial infection can accompany tooth resorption. In that case, swollen granular tissue with blood vessels replaces the lost parts of your tooth structure.
This type of resorption occurs when the lost dental tissue is replaced by bone. The resorptive process is usually gradual and may take years before irreversible damage to the tooth structure occurs.

Causes of Internal Resorption

While the exact cause of internal resorption is unclear, the process has several known risk factors, including:

  • Injury to the pulp
  • Infections affecting the pulp, leading to pulpal inflammation
  • Overheating tooth tissue during restorative dental procedures
  • Injury to the pulp during the repositioning of a tooth (auto-transplantation treatment)

Once internal resorption begins, it continues for as long as there’s any remaining pulp. Only treatment can stop the resorptive process and protect the remaining mineralized dental issue from further damage.

External Resorption

External tooth resorption is the loss of tooth structure after injury or infection in the periodontal ligament. It is a more prevalent resorptive process that impacts the external surface of a tooth.

There are five categories of external tooth resorption. They are surface resorption, inflammatory resorption, replacement resorption, cervical resorption and transient apical breakdown.

Surface Resorption

This resorption generally affects the cementum, which is mineral-based tissue surrounding the dentin of the root. The cementum will have superficial cavity-like damage, although the dentin’s outermost layer can also be impacted.

External surface resorption is naturally self-limiting, meaning that it isn’t usually severe enough to warrant treatment. Injury is the main cause of this type of tooth structure breakdown.

Inflammatory Resorption

As with internal resorption, inflammation may accompany an external resorptive process affecting any tooth. The origin of the bacterial infection is the main difference between the inflammatory responses.

In this case, the periodontal ligament (instead of the pulp) becomes swollen due to infection.

Replacement Resorption

With external replacement resorption, bone gradually replaces the lost parts of the tooth structure. Trauma and tooth movement may cause this problem.

It may be expected for children’s teeth to experience resorption. Still, in adults, resorption is typically a sign of tooth injury that can translate to long-lasting damage and even loss of teeth.

Cervical Resorption

This condition occurs when hard tissue within the cervical area of a tooth’s root surface begins to break down. It has several predisposing factors, including:

  • Injury to dental tissue
  • Teeth straightening or movement, such as using braces
  • Gum disease treatment
  • Tooth discoloration treatment

Transient Apical Breakdown

Transient apical breakdown occurs when the tip of the tooth’s root undergoes temporary resorption after injury. Because the injured tissues repair spontaneously, this breakdown doesn’t require treatment.

There’s usually no permanent damage to the periodontal ligament, and the problem generally goes away in one year without intervention.

Signs and Symptoms of Tooth Resorption

Most people with tooth resorption don’t exhibit any visible signs at early stages of the condition. Imaging techniques like X-ray can help detect common symptoms such as:

  • Loss of tooth tissue is easier to detect, especially if you have external resorption
  • Discoloration of the affected tooth, such as yellowish brown or pinkish blue
  • Cavity-like holes (perforation)
  • Swelling in your gum around the infected tooth
  • Dental decay, lesions, and other signs of breakdown on the impacted tooth’s surface
  • Infection and swelling usually causes tooth ache
  • Abnormal spacing between teeth

Tooth Resorption Treatment Options

The successful treatment of conditions like tooth resorption depends on early, accurate diagnosis. That is why it’s important to make routine dental exams a vital part of your healthy living.

Once an endodontist correctly diagnoses you with a type of tooth resorption on time, they can prescribe or provide the necessary interventions to prevent further damage to the tooth structure. The right therapy for you will depend on factors like:

  • Your medical history
  • Whether your tooth resorption is external, internal, or both
  • Severity of the structural breakdown in the affected tooth determines whether restoration is possible

The primary treatment options for tooth resorption are a root canal procedure, calcium hydroxide therapy and a tooth extraction.

Root Canal

A root canal is usually the most appropriate remedy for restorable tooth resorption. In most cases, the procedure effectively halts resorption originating within the pulp of the tooth because it cuts blood supply to the resorbing cells and tissues. It involves three main components:

  • Identification and preparation of access cavities for root canal. The dental care specialist will be cautious to preserve the undamaged remaining parts of the tooth structure, including the roof of the pulp chamber.
  • Removal of tissue supplying blood to the cells destroying the tooth’s structure.
  • Disinfection of the root canal system.

Calcium Hydroxide Therapy

The presence of cavity-like holes on the surface of the affected tooth may complicate treatment. Your endodontist may fill the holes with calcium hydroxide to slow down if not stop the resorption process.


Extraction is a last resort measure suitable for severe internal and external tooth resorption. If neither calcium hydroxide nor root canal therapy works for you, tooth removal is usually unavoidable.

Today, replacement resorption in adults has no known treatment. Tooth extraction is usually the only viable intervention.

Because this type of resorption occurs gradually, you may have several months to several years before you may need to replace the affected tooth.


Internal Resorption: an Unusual Form of Tooth Resorption. Medical Journal, Armed Forces India. Date Fetched: August 21, 2021

Tooth Resorption Part II - External Resorption: Case Series. Journal of Conservative Dentistry. Date Fetched: August 22, 2021

Root Resorption Classifications: A Narrative Review and a Clinical Aid Proposal for Routine Assessment. (November 21, 2018). European Endodontic Journal. Date fetched: August 27, 2021.

Disclaimer: This article is intended to promote understanding of and knowledge about general oral health topics. It is not intended to serve as dental or other professional health advice and is not intended to be used for diagnosis or treatment of any condition or symptom. You should consult a dentist or other qualified healthcare provider with any questions you may have regarding a medical condition or treatment.