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Symptoms of a Failed Root Canal

Let’s face it: Root canal therapy isn’t something you want on your to-do list. And even with a quick and comfortable experience, a repeat procedure is not something that most people would be happy about.

Unfortunately, root canal therapy is not always 100% successful. Several factors may lead to reinfection of the tooth, sending you back to your dental professional for root canal retreatment. And it’s important to note that you may not experience the symptoms of failed root canal therapy right away. They can occur months or even years after the original procedure is performed.*

Reasons Why Root Canals Fail

GentleWave ProcedureFailure to Clean the Entire Root Canal

Root canals in the root of a tooth can be curved, and small ones may be difficult to see.1 Not only that, standard root canal treatment can leave behind biofilm, which are sticky bacterial colonies that can be difficult to remove.2,Left untreated, the bacteria remaining in the tooth can grow, and could result in reinfection.**

A Breakdown in the Dental Crown

If the dental crown used to protect the tooth cracks, breaks or is placed too late after the root canals are cleaned, bacteria can reenter the root canals.*

A Breakdown of the Inner Seal

Over time, the inner seal placed inside your tooth during root canal therapy can erode, which may allow bacteria back into the root canals. **

Signs of Root Canal Therapy Failure

The symptoms of a failed root canal treatment may be similar to what you experienced when you first needed root canal therapy. They include:


With standard root canal treatment, you may feel some pain in the days following the procedure. But if the pain lingers more than a few days—or if the tooth feels better, then begins to hurt again—it can be a sign that bacteria and infection are once again taking hold.**


Facial swelling or swelling inside your mouth that occurs a while after your procedure may be signs of reinfection and should be addressed by your dentist or endodontist as soon as possible.


If you experience discharge from the area around the treated tooth, it may indicate that reinfection has occurred and an abscess has formed. Many people experience pain with an abscess, but some do not.*** Therefore, it’s important to contact your dental professional if you notice any discharge.

What to Do if You Think Your Root Canal Failed

If you experience pain or swelling after root canal treatment, your first course of action is to contact your dentist or endodontist, who will assess your symptoms and discuss with you if you need retreatment.

Root Canal Therapy Options

Patients who have experienced failed root canal therapy typically have two options—a second standard root canal treatment to help save the tooth, or tooth extraction in which the tooth is removed. But a clinical research study has shown that most patients prefer to save their natural tooth,‡‡ which places a precedence on root canal therapy over tooth extraction and dental implant.

If you need root canal therapy, but you don’t want standard root canal treatment and you want to retain your natural tooth, the GentleWave® Procedure may be just what you’re looking for.

The GentleWave Procedure is a minimally invasive alternative to standard root canal treatment.1 Using Multisonic Ultracleaning® technology, the GentleWave System reaches into the microscopic spaces that standard root canal treatment frequently cannot.2,3 It’s so effective at cleaning and disinfecting the root canal system, there’s less chance of failure over time!2,4

Find a GentleWave® Provider

If you’d like to find a dentist or endodontist in your area with the GentleWave System, use our Provider Locator. Enjoy a minimally invasive alternative to standard root canal treatment with the GentleWave Procedure.

* 1-800-DENTIST


** Colgate


*** Colgate

‡‡ Azarpazhooh A et al. (2016) J Endod. 42:365-70