Tooth Resorption: Why it Occurs, and Types of Resorptions

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Tooth resorption is the phenomenon of dissolution of all the hard tissues of the tooth i.e. the enamel, the dentin, and the cementum.

Tooth Resorption

These hard tissues are broken down and lost completely, eventually leading to tooth loss. This is the work of the osteoclast cells that are also responsible for baby tooth resorption.

To understand tooth resorption, we first have to understand the structure of a tooth. Each tooth crown consists of the outermost white, hard enamel. It is the hardest tissue found in the human body.

The next layer, inner to the enamel is dentin and is yellowish brown. The innermost layer of the tooth is the pulp. It is the nerve supply and the blood supply of the tooth.

Similarly, the tooth root has an outer cementum layer that helps the tooth root to bind to the socket. Inner to the cementum is dentin and inner to dentin is the pulp.

Types of Tooth Resorption

External Tooth Resorption or External Resorption

This is the more common form of resorption and can affect the outer parts of the tooth or the root resulting in external root resorption. It can appear as scooped-out holes on the tooth surface. While on the root, it can manifest as the shortening of the length of the root or flattening of the root apex or tip.

Internal Tooth Resorption or Internal Resorption

This is a less common form and typically starts from the inside of the tooth i.e. the pulp chamber. They are inconspicuous and go undetected until a routine dental examination and X-rays show dark spots in the innermost part of the tooth.

Why Tooth Resorption occurs

Causes for External Tooth Resorption

There can be multiple causes of external resorption, some of the most common being-

  1. Trauma- accidental injury to tooth or jaw might result in external resorption.
  2. Orthodontic appliances- prolonged use of braces or inaccurately fabricated oral appliances such as retainers or nightguards can cause undue pressure on tooth roots leading to external resorption.
  3. Oral Habits- habits such as clenching of teeth or night grinding or bruxism might result in external resorption for the same reason; undue pressure on tooth root.
  4. Dental procedures- dental procedures such as tooth whitening might cause external resorption.

Causes for Internal Tooth Resorption

The exact cause of internal resorption is unclear but the following are some of the causes that might trigger it-

Internal Tooth Resorption
  1. Trauma- just like external resorption, internal resorption can be triggered by trauma to the tooth or jaw.
  2. Dental caries- inflammation of the pulp chamber might lead to internal resorption also called inflammatory resorption.
  3. Orthodontic treatment- similar to external resorption, internal resorption can result from the orthodontic tooth movement as well.

Symptoms of Tooth Resorption

Tooth resorption (either external or internal) doesn’t present any symptoms in the early stages and might even go undetected for years until they show up in the X-rays during routine dental exams. Furthermore, by the time they start showing symptoms, 

Early signs and symptoms

Some of the early signs and symptoms constitute:-

  1. Tooth sensitivity- extreme sensitivity to hot and cold food and beverages might be an early indicator. The same can be true for sweet food and beverages.
  2. Discoloration near gumline- reddish or pink-colored discoloration near the gumline may indicate the tooth resorption part.
  3. Swelling- any swelling or inflammation around a tooth might indicate a resorptive lesion.
  4. Unusual spacing between teeth might be an indication of a resorptive lesion.

Advanced symptoms

While the early symptoms might not be severe, the advanced lesions manifest themselves as follows:-

  1. Persistent pain- a throbbing or dull toothache might be an indication of the lesion.
  2. Mobility of teeth- the affected teeth might become loose in advanced lesions.
  3. Brittle teeth- the tendency of teeth to chip easily might indicate advanced lesions.
  4. Cavities in teeth without any explainable cause (such as bacteria for caries) might be a strong indication of resorption.
  5. Tooth abscess- advanced resorption can manifest as cysts or abscesses in the affected tooth.

Diagnosing Tooth Resorption

Resorption is typically diagnosed only when the patient is advised X-rays or upon a comprehensive oral examination.

Dental examination

During a comprehensive dental examination, your dentist might come across pink or reddish discolorations around the cervical region of the tooth. This might be internal resorption. Whereas, external resorption might look like cavities or holes in the tooth.

Xrays and imaging tests

Imaging tests are better at providing a definitive diagnosis of the lesion. While internal resorption looks like a dark spot in the center of the tooth, external can manifest in the form of root shortening and flattening of the root apex.

Treatment Options for Tooth Resorption

Treatment often depends on the stage and extent of damage to a tooth while trying to preserve the most of it.

Monitoring and observation

Regular monitoring and observation are helpful in the detection of the lesion at an early stage.

Root canal treatment

A root canal is the most common line of treatment to preserve what is remaining of the tooth structure. 

Root Canal Treatment

A dental cap or crown is required to keep the tooth safe from further injuries.

Tooth extraction

In most advanced cases there is no option left but to extract the tooth. However, the patient can opt for an implant or dental ridge to maintain the appearance of the teeth intact.

Preventing Tooth Resorption

While there is no foolproof way to prevent it from occurring, since the actual cause can vary from a mild bacterial infection of the tooth to a severe accidental injury, we can still adopt some of the habits that prolong the life of our pearly whites.

Maintaining good oral hygiene

The importance of a diligent oral hygiene regimen can’t be emphasized enough. However, most people don’t follow the ‘twice for two minutes’ rule when it comes to toothbrushing. Flossing daily is as important as brushing twice daily.

Regular dental checkups

Routine dental check-ups are crucial for the early detection of the disease. This can save a lot of inconvenience to the patient and can save the tooth rather than having to remove it in the advanced stages of the lesion.


While resorption is a common phenomenon in children, it is an oral condition that requires immediate attention in adults.

Understanding the causes, symptoms, prevention, and treatment can better enable you to prioritize your oral health and seek the help of a dental professional for timely intervention.

So, pay close attention to your teeth and don’t skip the regular visits to your dentist.

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