Why Root Canals Fail — And What Can Be Done About It

If you’ve recently had a root canal or are considering one, you might be wondering: why do root canals fail? Root canal treatment is one of the most effective ways to save a damaged or infected tooth. While root canals have a high success rate — often over 90% — failures do happen sometimes soon after or even years after. This article is to help you understanding the common reasons behind root canal failure and what can be done about it after it happens.

Top Reasons Why Root Canals Fail



  1. Incomplete Cleaning and Shaping of the Root Canals
    Sometimes, tiny canals or complex anatomy make it hard to completely remove all infected tissue. Bacteria left behind can cause reinfection, leading to pain and swelling.
  2. Missed Canals
    Some teeth have extra or unusual canals that can be missed during treatment. These untreated canals may harbor bacteria that cause the infection to return.
  3. Cracked or Fractured Tooth
    A crack in the tooth can allow bacteria to enter, even after a root canal. This often leads to persistent infection and may require retreatment or extraction.
  4. Poor Seal or Filling
    If the filling material does not completely seal the canals, bacteria can re-enter and cause infection. This can happen if the filling deteriorates or if there was a technical error during treatment.
  5. New Decay
    Tooth decay that develops after a root canal can expose the treated area to bacteria, leading to failure.
  6. Delayed Crown Placement
    Root canal-treated teeth often need crowns to protect them. Delays in getting a crown can cause the tooth to weaken or crack, increasing the risk of failure.


Symptoms of a Failed Root Canal


  • Persistent or recurring pain
  • Swelling or tenderness near the treated tooth
  • Tooth discoloration
  • Gum boil or pimple near the root of the tooth
  • Sensitivity to pressure or chewing



If you experience these symptoms, it’s important to visit your dentist promptly.

How to Prevent Root Canal Failure


  • Choose an experienced endodontist or dentist specializing in root canals
  • Get a crown placed as soon as recommended


Retreatment and Alternatives

If a root canal fails, retreatment may be possible to save the tooth. In some cases, an apicoectomy (surgical removal of the root tip with retrograde fill) or extraction might be necessary. Your dentist will evaluate your options and recommend the best course of action.

Frequently asked questions about failing root canals

FAQ: Why Do Root Canals Fail?

How common is root canal failure?

Root canal treatments succeed over 90% of the time, but 5-15% of cases may require retreatment or further care.

What are the early signs that a root canal might have failed?

Symptoms include persistent pain, swelling, gum bumps near the tooth, discoloration, or sensitivity when biting.

What treatment options are available if a root canal fails?

Options include root canal retreatment, apicoectomy (surgical root tip removal), or extraction if necessary.

How important is follow-up care after a root canal?

Follow-up care is critical to monitor healing, prevent reinfection, and ensure crowns or restorations are placed promptly.

Can lifestyle habits affect root canal success?

Yes. Poor oral hygiene, smoking, and chewing hard foods can increase the risk of complications after treatment.

What should I do if I experience pain after a root canal?

Contact your dentist promptly for an evaluation to address potential complications early.

Why choose us in Riverview?


Dr Castellano has been doing root canal treatments since 1999. He has completed many continuing dental education hours on root canal therapy. Our goal is to  to preserve your natural teeth and prevent complications.


If this is not possible it's great to know we can handle the other treament alternatives. Dr Castellano surgically places and restores implants. He is also very well versed in the convetional dentistry of fixed bridges and partial dentures to restore your smile


If you’re experiencing discomfort or have concerns about a previous root canal, contact us today for a thorough evaluation.

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