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Why is my tooth black under my root canal?

A root canal treated tooth turning black is a common occurrence that can happen for various reasons. While it may look alarming, a dark tooth after a root canal is not necessarily a cause for concern. Understanding the potential causes and treatments can help patients evaluate the health of a post-root canal tooth.

What causes a tooth to turn black after a root canal?

Here are some of the most common reasons a tooth may become dark after a root canal procedure:

  • Pulp left behind – If some of the pulp tissue inside the tooth is accidentally left behind after cleaning and shaping the canals, it can discolor and decay over time.
  • Root canal sealer – Chemical root canal sealers are used to fill and seal the root canal space. Some sealers can stain the interior of the tooth black.
  • Metal posts – Metal posts and screws used to rebuild crowns after a root canal can cause black discoloration.
  • Pulp necrosis – If the pulp tissue dies due to infection or trauma before the root canal is performed, it can disintegrate into dark fragments.
  • Secondary infection – Germs entering through micro-cracks or an incomplete seal can cause pus and bloody discharge that stains the inner tooth.
  • Calculus build-up – Mineral deposits and tartar deep inside the root canal system can lead to blackening.

Should I be worried if my root canal tooth turns black?

A discolored tooth after root canal treatment does not necessarily indicate failure or issues. As long as there are no other symptoms like pain, swelling or sensitivity, a dark root canal tooth may not require intervention. However, a blackened tooth can signify:

  • Infection due to bacteria left behind – This requires cleaning and re-sealing the canal.
  • An incomplete or poor quality root canal – The procedure may need to be redone.
  • The need for a crown or other restoration – Tooth discoloration indicates the underlying tooth structure is compromised.

It is best to see a dentist to determine the exact cause and whether any treatment is required. Leaving an infected or failing root canal untreated can result in an abscess, bone loss, swelling and tooth loss.

What treatments can fix a discolored tooth after a root canal?

Here are some ways to restore the natural color of a root filled tooth that has turned black or darkened:

  • Root canal retreatment – The old root canal filling material is removed and the canals are cleaned, disinfected, and freshly sealed.
  • Internal bleaching – A peroxide gel is applied inside the tooth and temporarily sealed to lighten the color.
  • Dental post and core build-up – Removing metal posts and placing tooth-colored posts and composite filling can reduce dark stains.
  • Dental crown – Crowns, veneers, or other tooth-colored restorations can improve the appearance of a discolored tooth.

Here is a comparison of the two most effective options:

Root Canal Retreatment Internal Bleaching
  • Addresses underlying infection or issues
  • Restores tooth health and function
  • Has a higher long-term success rate
  • More invasive
  • Higher costs
  • Improves tooth color and appearance
  • Does not fix any undying problems
  • Lower success rate long-term
  • More conservative approach
  • Lower costs

When should I see a dentist about a discolored root canal tooth?

You should make an appointment with your dentist if you notice any of the following:

  • The tooth changes color within a few weeks or months after root canal treatment
  • The darkening tooth is painful, sensitive or feels different
  • You see bumps, swelling, or pus around the tooth
  • The tooth discoloration is rapidly getting worse
  • You are unhappy with the unsightly appearance of the tooth

Seeing a dentist promptly can help determine if retreatment, restoration, or extraction is required. This can also prevent more invasive treatments later on if the problem progresses unchecked.

Can I prevent my root canal tooth from turning black?

While it is not always possible to prevent internal discoloration, you can minimize the risk by:

  • Selecting an experienced endodontist to perform the root canal
  • Insisting on rubber dam isolation during the procedure
  • Asking for temporary filling to be placed immediately after the root canal
  • Following all post-op care instructions carefully
  • Placing a dental crown over the tooth to protect it
  • Maintaining excellent oral hygiene to prevent infection
  • Getting regular dental checkups to catch issues early

What is the outlook for a blackened root canal treated tooth?

With proper diagnosis and treatment, a dark root canal tooth can often be restored successfully. Here are the general prognosis scenarios:

  • With root canal re-treatment success rates are over 90%
  • Internal bleaching lightens tooth shade in about 75% of cases
  • Well-fitted crowns have a 5-10 year survival rate
  • Tooth extractions are close to 100% successful

As long as the cause is identified correctly and suitable correction is performed in a timely manner, blackened root canal teeth can regain function and aesthetics.

When is extraction the only option?

Extraction is the only solution in situations where:

  • The tooth is severely infected and cannot be saved even after repeated root canal treatment
  • There is extensive decay or fracture making the tooth unrestorable
  • Finances do not permit complex re-treatment procedures
  • Other teeth need to be extracted for dental prostheses
  • Patient preferences favor removal over other treatments

However, keeping natural teeth as long as possible is always preferable. All other options should be considered before turning to extraction.


While a black tooth after a root canal can look disturbing, timely diagnosis and treatment can help restore a healthy and bright smile in most cases. Patients must see a dentist when any discoloration, pain or abnormalities are noticed so that the ideal solution can be implemented based on their unique situation.